{"id":1468,"date":"2016-10-09T14:19:57","date_gmt":"2016-10-09T06:19:57","guid":{"rendered":"http:\/\/nick.txtcc.com\/?p=1468"},"modified":"2016-10-09T14:19:58","modified_gmt":"2016-10-09T06:19:58","slug":"mysql-index%e8%af%a6%e8%a7%a3","status":"publish","type":"post","link":"http:\/\/nick.txtcc.com\/index.php\/linux\/1468","title":{"rendered":"MySQL Index\u8be6\u89e3"},"content":{"rendered":"<p>FROM:<a href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482\">http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482<\/a><\/p>\n<p>\u2460<a class=\"replace_word\" title=\"undefined\" href=\"http:\/\/lib.csdn.net\/base\/14\" target=\"_blank\">MySQL<\/a> Index<\/p>\n<p>\u4e00\u3001SHOW INDEX\u4f1a\u8fd4\u56de\u4ee5\u4e0b\u5b57\u6bb5<\/p>\n<p>1\u3001Table \u8868\u7684\u540d\u79f0\u3002<\/p>\n<p>2\u3001 Non_unique \u5982\u679c\u7d22\u5f15\u4e0d\u80fd\u5305\u62ec\u91cd\u590d\u8bcd,\u5219\u4e3a0,\u5982\u679c\u53ef\u4ee5\u5219\u4e3a1\u3002<\/p>\n<p>3\u3001 Key_name \u7d22\u5f15\u7684\u540d\u79f0<\/p>\n<p>4\u3001 Seq_in_index \u7d22\u5f15\u4e2d\u7684\u5217\u5e8f\u5217\u53f7\uff0c\u4ece1\u5f00\u59cb\u3002<\/p>\n<p>5\u3001 Column_name \u5217\u540d\u79f0\u3002<\/p>\n<p>6\u3001 Collation \u5217\u4ee5\u4ec0\u4e48\u65b9\u5f0f\u5b58\u50a8\u5728\u7d22\u5f15\u4e2d\u3002\u5728MySQL\u4e2d\uff0c\u6709\u503c\u2018A\u2019\uff08\u5347\u5e8f\uff09\u6216NULL\uff08\u65e0\u5206\u7c7b\uff09\u3002<\/p>\n<p>7\u3001Cardinality \u7d22\u5f15\u4e2d\u552f\u4e00\u503c\u7684\u6570\u76ee\u7684\u4f30\u8ba1\u503c\u3002\u901a\u8fc7\u8fd0\u884cANALYZE TABLE\u6216myisamchk -a\u53ef\u4ee5\u66f4\u65b0\u3002\u57fa\u6570\u6839\u636e\u88ab\u5b58\u50a8\u4e3a\u6574\u6570\u7684\u7edf\u8ba1\u6570\u636e\u6765\u8ba1\u6570\uff0c\u6240\u4ee5\u5373\u4f7f\u5bf9\u4e8e\u5c0f\u578b\u8868\uff0c\u8be5\u503c\u4e5f\u6ca1\u6709\u5fc5\u8981\u662f\u7cbe\u786e\u7684\u3002\u57fa\u6570\u8d8a\u5927\uff0c\u5f53\u8fdb\u884c\u8054\u5408\u65f6\uff0cMySQL\u4f7f\u7528\u8be5\u7d22\u5f15\u7684\u673a\u4f1a\u5c31\u8d8a\u5927\u3002<\/p>\n<p>8\u3001Sub_part \u5982\u679c\u5217\u53ea\u662f\u88ab\u90e8\u5206\u5730\u7f16\u5165\u7d22\u5f15\uff0c\u5219\u4e3a\u88ab\u7f16\u5165\u7d22\u5f15\u7684\u5b57\u7b26\u7684\u6570\u76ee\u3002\u5982\u679c\u6574\u5217\u88ab\u7f16\u5165\u7d22\u5f15\uff0c\u5219\u4e3aNULL\u3002<\/p>\n<p>9\u3001 Packed \u6307\u793a\u5173\u952e\u5b57\u5982\u4f55\u88ab\u538b\u7f29\u3002\u5982\u679c\u6ca1\u6709\u88ab\u538b\u7f29\uff0c\u5219\u4e3aNULL\u3002<\/p>\n<p>10\u3001 Null \u5982\u679c\u5217\u542b\u6709NULL\uff0c\u5219\u542b\u6709YES\u3002\u5982\u679c\u6ca1\u6709\uff0c\u5219\u8be5\u5217\u542b\u6709NO\u3002<\/p>\n<p>11\u3001 Index_type \u7528\u8fc7\u7684\u7d22\u5f15\u65b9\u6cd5\uff08BTREE, FULLTEXT, HASH, RTREE\uff09\u3002<\/p>\n<p>12\u3001 Comment \u591a\u79cd\u8bc4\u6ce8\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528db_name.tbl_name\u4f5c\u4e3atbl_name FROM db_name\u8bed\u6cd5\u7684\u53e6\u4e00\u79cd\u5f62\u5f0f\u3002\u8fd9\u4e24\u4e2a\u8bed\u53e5\u662f\u7b49\u4ef7\u7684\uff1a<\/p>\n<p>mysql>SHOW INDEX FROM mytable FROM mydb;<\/p>\n<p>mysql>SHOW INDEX FROM mydb.mytable;<\/p>\n<p>\u4e8c\u3001\u4f7f\u7528 CREATE INDEX \u521b\u5efa\u7d22\u5f15<\/p>\n<p>\u5982\u679c\u8981\u4e3a\u5df2\u5b58\u5728\u7684\u8868\u521b\u5efa\u7d22\u5f15\uff0c\u5c31\u9700\u8981\u4f7f\u7528 CREATE INDEX \u547d\u4ee4\u6216 ALTER TABLE \u6765\u521b\u5efa\u7d22\u5f15\u3002<\/p>\n<p>CREATEINDEX idxtitle ON tablename (title)<\/p>\n<p>\u8fd9\u6761\u547d\u4ee4\u5c06\u521b\u5efa\u4e0e CREATE TABLE \u547d\u4ee4\u76f8\u540c\u7684\u7d22\u5f15\u3002<\/p>\n<p>\u4e09\u3001\u4f7f\u7528 ALTER TABLE \u521b\u5efa\u7d22\u5f15<\/p>\n<p>ALTER TABLE tablename ADD INDEX idxtitle (title)<\/p>\n<p>\u56db\u3001\u67e5\u770b\u548c\u5220\u9664\u7d22\u5f15<\/p>\n<p>\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u547d\u4ee4\u6765\u67e5\u770b\u5df2\u5b58\u5728\u7684\u7d22\u5f15\uff1a<\/p>\n<p>SHOW INDEX FROM tablename<\/p>\n<p>DROP INDEX indexname ON tablename<\/p>\n<p>DROP INDEX \u5c06\u5220\u9664 tablename \u8868\u4e0a\u7684 indexname \u7d22\u5f15\uff0cindexname \u5c31\u662f\u6211\u4eec\u521b\u5efa\u8868\u65f6\u6307\u5b9a\u7684\u7d22\u5f15\u540d\u3002<\/p>\n<p>########################################<\/p>\n<p>createtable c(id char(20) not null primary key,<code>index<\/code> char(10));<\/p>\n<p>\u95ee\u98981.\u5982\u679c\u6211\u5fd8\u8bb0\u628aid\u8bbe\u4e3a\u4e3b\u952e\u73b0\u5728\u8be5\u600e\u4e48\u529e\uff1f\u8f93\u5165\u4ec0\u4e48\u547d\u4ee4\uff1f<\/p>\n<p>ALTER TABLE record<\/p>\n<p>ADD PRIMARY KEY (id);<\/p>\n<p>\u4f8b\u5982\uff1aALTER TABLE <code>abc<\/code> ADD PRIMARY KEY(<code>a<\/code>)\uff1b<\/p>\n<p>\u95ee\u98982.\u5982\u679c\u6211\u60f3\u628aid\u8bbe\u4e3a\u4e3b\u952e\uff0c\u540c\u65f6\u60f3\u628aname\u6539\u4e3anot null\uff0c\u4e14\u6539\u4e3avarchar(10),\u80fd\u4e0d\u80fd\u7528\u4e00\u53e5\u547d\u4ee4\u5b8c\u6210\u95ee\u98982\uff1f<\/p>\n<p>ALTER TABLE record<\/p>\n<p>ADD PRIMARY KEY (id),<\/p>\n<p>CHANGEname varchar(10) not null;<\/p>\n<p>########################################<\/p>\n<p><strong>\u7d22\u5f15 mysql index<\/strong><\/p>\n<p>\u7d22\u5f15\u662f\u4e00\u79cd\u6570\u636e\u7ed3\u6784\uff0c\u53ef\u4ee5\u662fB-tree, R-tree, \u6216\u8005 hash \u7ed3\u6784\u3002\u5176\u4e2dR-tree \u5e38\u7528\u4e8e\u67e5\u8be2\u6bd4\u8f83\u63a5\u8fd1\u7684\u6570\u636e\uff1bB-trees\u9002\u5408\u7528\u4e8e\u67e5\u627e\u67d0\u8303\u56f4\u5185\u7684\u6570\u636e\uff0c\u53ef\u4ee5\u5f88\u5feb\u7684\u4ece\u5f53\u524d\u6570\u636e\u627e\u5230\u4e0b\u6761\u6570\u636e\uff1bhash\u7ed3\u6784\u5219\u9002\u7528\u4e8e\u968f\u673a\u8bbf\u95ee\u7684\u573a\u5408\uff0c\u67e5\u627e\u6bcf\u6761\u6570\u636e\u7684\u65f6\u95f4\u51e0\u4e4e\u76f8\u540c\u3002\u663e\u7136\uff0c\u82e5\u8981\u67e5\u627e\u67d0\u4e2a\u65f6\u95f4\u6bb5\u7684\u6570\u636e\uff0c\u7528B-tree\u7ed3\u6784\u8981\u6bd4hash\u7ed3\u6784\u5feb\u597d\u591a\u3002<\/p>\n<p>\u4f18\u5316\u67e5\u8be2\u7684\u6709\u6548\u65b9\u6cd5\u662f\u4e3a\u7ecf\u5e38\u67e5\u8be2\u7684\u5b57\u6bb5\u5efa\u7acb\u7d22\u5f15\uff0c\u5982\u65e0\u7d22\u5f15\u67e5\u8be2\u6570\u636e\u65f6\uff0c\u4f1a\u904d\u5386\u6574\u5f20\u8868(\u591a\u4e48\u6050\u6016\u554a);\u82e5\u6709\u4e86\u7d22\u5f15\u67e5\u627e\u4f1a\u5bb9\u6613\u5f88\u591a\u3002\u5f53\u8fdb\u884c UPDATE, DELETE, \u4ee5\u53ca INSERT \u64cd\u4f5c\u65f6\uff0cmysql\u4f1a\u81ea\u52a8\u66f4\u65b0\u7d22\u5f15\u4fe1\u606f\u3002<\/p>\n<p>1.\u521b\u5efa\u548c\u5220\u9664\u7d22\u5f15( Creating and dropping indexes )<\/p>\n<p>\u521b\u5efa\uff1a<\/p>\n<div class=\"dp-highlighter bg_xhtml\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[xhtml]<\/strong>\u00a0<a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/luketty\/article\/details\/5772429#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/luketty\/article\/details\/5772429#\">copy<\/a>\n<div><\/div>\n<div><embed id=\"ZeroClipboardMovie_1\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_1\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-xml\" start=\"1\">\n    <li class=\"alt\">mysql<span class=\"tag\">><\/span>\u00a0USE\u00a0sakila;<\/li>\n    <li>Database\u00a0changed<\/li>\n    <li class=\"alt\">mysql<span class=\"tag\">><\/span>\u00a0CREATE\u00a0INDEX\u00a0idx_actor_first_name\u00a0ON\u00a0actor\u00a0(first_name);<\/li>\n    <li>\u6216\u8005<\/li>\n    <li class=\"alt\">mysql<span class=\"tag\">><\/span>\u00a0ALTER\u00a0TABLE\u00a0actor\u00a0ADD\u00a0INDEX\u00a0idx_actor_first_name\u00a0(first_name);<\/li>\n<\/ol>\n<\/div>\n<p>PS:\u5f53\u7528 create index \u521b\u5efa\u7d22\u5f15\u65f6,\u5fc5\u987b\u6307\u5b9a\u7d22\u5f15\u7684\u540d\u5b57\uff0c\u5426\u5219mysql\u4f1a\u62a5\u9519\uff1b\n\u7528 ALTER TABLE \u521b\u5efa\u7d22\u5f15\u65f6\uff0c\u53ef\u4ee5\u4e0d\u6307\u5b9a\u7d22\u5f15\u540d\u5b57\uff0c\u82e5\u4e0d\u6307\u5b9amysql\u4f1a\u81ea\u52a8\u751f\u6210\u7d22\u5f15\u540d\u5b57<\/p>\n<p>\u5efa\u7acb\u7d22\u5f15\u65f6\uff0c\u82e5\u4e0d\u60f3\u7528\u5b58\u50a8\u5f15\u64ce\u7684\u9ed8\u8ba4\u7d22\u5f15\u7c7b\u578b\uff0c\u53ef\u4ee5\u6307\u5b9a\u7d22\u5f15\u7684\u7c7b\u578b:<\/p>\n<div class=\"dp-highlighter bg_css\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[css]<\/strong>\u00a0<a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/luketty\/article\/details\/5772429#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/luketty\/article\/details\/5772429#\">copy<\/a>\n<div><\/div>\n<div><embed id=\"ZeroClipboardMovie_2\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_2\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-css\" start=\"1\">\n    <li class=\"alt\">mysql>\u00a0ALTER\u00a0TABLE\u00a0temp_index<\/li>\n    <li>\u00a0ADD\u00a0INDEX\u00a0(first_name),<\/li>\n    <li class=\"alt\">\u00a0ADD\u00a0INDEX\u00a0lname\u00a0(last_name)\u00a0USING\u00a0BTREE<\/li>\n<\/ol>\n<\/div>\n<p>\u5220\u9664\uff1a<\/p>\n<div class=\"dp-highlighter bg_css\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[css]<\/strong>\u00a0<a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/luketty\/article\/details\/5772429#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/luketty\/article\/details\/5772429#\">copy<\/a>\n<div><\/div>\n<div><embed id=\"ZeroClipboardMovie_3\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_3\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-css\" start=\"1\">\n    <li class=\"alt\">DROP\u00a0INDEX\u00a0indexname\u00a0ON\u00a0tblname<\/li>\n    <li>mysql>\u00a0DROP\u00a0INDEX\u00a0idx_actor_fname\u00a0ON\u00a0actor;<\/li>\n    <li class=\"alt\">mysql>\u00a0ALTER\u00a0TABLE\u00a0actor\u00a0DROP\u00a0INDEX\u00a0idx_actor_fname;<\/li>\n<\/ol>\n<\/div>\n<p>2.\u7d22\u5f15\u7c7b\u578b<\/p>\n<p>BTREE \u00a0\u00a0\u00a0\u9002\u5408\u8fde\u7eed\u8bfb\u53d6\u6570\u636e\nRTREE \u00a0\u00a0\u00a0\u9002\u5408\u6839\u636e\u4e00\u6761\u6570\u636e\u627e\u9644\u8fd1\u7684\u6570\u636e\nHASH\u00a0\u00a0\u00a0\u00a0\u00a0 \u9002\u5408\u968f\u673a\u8bfb\u53d6\u6570\u636e\nFULLTEXT\nSPATIAL<\/p>\n<p>\u67e5\u770b\u67d0\u4e2a\u8868\u4e2d\u5b58\u5728\u7684\u7d22\u5f15\u7c7b\u578b<\/p>\n<div class=\"dp-highlighter bg_css\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[css]<\/strong>\u00a0<a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/luketty\/article\/details\/5772429#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/luketty\/article\/details\/5772429#\">copy<\/a>\n<div><\/div>\n<div><embed id=\"ZeroClipboardMovie_4\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_4\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-css\" start=\"1\">\n    <li class=\"alt\">mysql>\u00a0SELECT\u00a0INDEX_NAME,INDEX_TYPE<\/li>\n    <li>->\u00a0FROM\u00a0INFORMATION_SCHEMA.STATISTICS<\/li>\n    <li class=\"alt\">->\u00a0WHERE\u00a0TABLE_NAME=\u2019temp_index\u2019;<\/li>\n    <li>+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+<\/li>\n    <li class=\"alt\">|\u00a0INDEX_NAME\u00a0|\u00a0INDEX_TYPE\u00a0|<\/li>\n    <li>+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+<\/li>\n    <li class=\"alt\">|\u00a0first_name\u00a0|\u00a0HASH\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0|<\/li>\n    <li>|\u00a0lname\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0|\u00a0BTREE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0|<\/li>\n    <li class=\"alt\">+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+<\/li>\n<\/ol>\n<\/div>\n<p>3.\u7d22\u5f15\u5197\u4f59<\/p>\n<p>\u5982\u679c\u4e24\u4e2a\u6216\u8005\u591a\u4e2a\u7d22\u5f15\u5305\u542b\u4e86\u76f8\u540c\u7684\u7d22\u5f15\u4fe1\u606f\uff0c\u90a3\u4e48\u5c31\u5b58\u5728\u7d22\u5f15\u5197\u4f59\u3002<\/p>\n<p>\u4e0d\u540c\u7c7b\u578b\u7684\u7d22\u5f15\u6709\u4e0d\u540c\u7684\u7d22\u5f15\u5197\u4f59\u5224\u65ad:\n(1) SPATIAL \u7d22\u5f15\nSPATIAL \u53ea\u80fd\u662f\u4e00\u4e2a\u7b80\u5355\u7d22\u5f15\uff0c\u4e0d\u80fd\u8bf4\u590d\u5408\u7d22\u5f15\uff1b\u5b58\u5728\u5197\u4f59\u7684\u60c5\u51b5\u662f\u540c\u4e00\u4e2a\u5b57\u6bb5\u6709\u4e24\u4e2a\u7d22\u5f15\u3002\n(2) FULLTEXT \u7d22\u5f15\n\u82e5\u4e00\u4e2aFULLTEXT\u7d22\u5f15\u662f\u53e6\u4e00\u4e2a\u7d22\u5f15\u7684\u5b50\u96c6(\u4e0d\u8003\u8651\u5b57\u6bb5\u987a\u5e8f),\u5219\u5b58\u5728\u5197\u4f59\u3002\n\u4f8b\u5982: \u8868\u4e2d\u5305\u542b\u5982\u4e0b\u4e24\u4e2a\u7d22\u5f15\n\u25a0 (field1)\n\u25a0 (field1, field2)\n(3) HASH \u7d22\u5f15\n\u82e5\u4e00\u4e2a\u7d22\u5f15\u5728\u4e0d\u8003\u8651\u5b57\u6bb5\u987a\u5e8f\u7684\u60c5\u51b5\u4e0b\uff0c\u7d22\u5f15\u5b57\u6bb5\u76f8\u540c\uff0c\u5219\u5b58\u5728\u5197\u4f59\u3002\n\u4f8b\u5982\uff1a\u8868\u4e2d\u5305\u542b\u5982\u4e0b\u4e24\u4e2a\u7d22\u5f15\n\u25a0 (field1, field2, field3)\n\u25a0 (field1, field3, field2)\n(4) BTREE \u7d22\u5f15\n\u82e5\u4e00\u4e2a\u7d22\u5f15\u662f\u53e6\u4e00\u4e2a\u7d22\u5f15\u7684\u5b50\u96c6(\u8003\u8651\u5b57\u6bb5\u987a\u5e8f),\u5219\u5b58\u5728\u5197\u4f59\u3002\n\u4f8b\u5982\uff1a\u8868\u4e2d\u5305\u542b\u5982\u4e0b\u4e24\u4e2a\u7d22\u5f15\n\u25a0 (field2)\n\u25a0 (field2, field1)<\/p>\n<p>PS\uff1a\u82e5\u4e24\u4e2a\u6216\u591a\u4e2a\u7d22\u5f15\u6709\u76f8\u540c\u7684\u7d22\u5f15\u5b57\u6bb5\u548c\u5b57\u6bb5\u987a\u5e8f\uff0c\u4f46\u662f\u6709\u4e0d\u540c\u7684\u7d22\u5f15\u7c7b\u578b\uff0c\u8fd9\u6837\u7684\u7d22\u5f15\u662f\u4e0d\u5197\u4f59\u7684\u3002\u56e0\u4e3a\u6bcf\u79cd\u7d22\u5f15\u7c7b\u578b\u6709\u81ea\u5df1\u7684\u7d22\u5f15\u503c\u3002<\/p>\n<p>######################################<\/p>\n<p><strong>\u6df1\u5165MySQL\u6570\u636e\u5e93\u7684\u7d22\u5f15<\/strong><\/p>\n<p>\u6458\u8981\uff1a\u672c\u6587\u4ecb\u7ecd\u7d22\u5f15\u7684\u7c7b\u578b\uff0c\u5df2\u7ecf\u5982\u4f55\u521b\u5efa\u7d22\u5f15\u505a\u4e86\u4ecb\u7ecd\uff0c\u5176\u4e2d\u6d89\u53ca\u4e09\u4e2a\u6bd4\u8f83\u91cd\u8981\u7684SQL\u8bed\u53e5\u2015\u2015ALTER TABLE\u3001CREATE\/DROP INDEX\u548cCREATE TABLE\uff0c\u6ce8\u610f\u5b83\u4eec\u7684\u7528\u6cd5\u3002<\/p>\n<p>\u7d22\u5f15\u662f\u52a0\u901f\u8868\u5185\u5bb9\u8bbf\u95ee\u7684\u4e3b\u8981\u624b\u6bb5\uff0c\u7279\u522b\u5bf9\u6d89\u53ca\u591a\u4e2a\u8868\u7684\u8fde\u63a5\u7684\u67e5\u8be2\u66f4\u662f\u5982\u6b64\u3002\u8fd9\u662f\u6570\u636e\u5e93\u4f18\u5316\u4e2d\u7684\u4e00\u4e2a\u91cd\u8981\u5185\u5bb9\uff0c\u6211\u4eec\u8981\u4e86\u89e3\u4e3a\u4ec0\u4e48\u9700\u8981\u7d22\u5f15\uff0c\u7d22\u5f15\u5982\u4f55\u5de5\u4f5c\u4ee5\u53ca\u600e\u6837\u5229\u7528\u5b83\u4eec\u6765\u4f18\u5316\u67e5\u8be2\u3002\u672c\u8282\u4e2d\uff0c\u6211\u4eec\u5c06\u4ecb\u7ecd\u7d22\u5f15\u7684\u7279\u70b9\uff0c\u4ee5\u53ca\u521b\u5efa\u548c\u5220\u9664\u7d22\u5f15\u7684\u8bed\u6cd5\u3002<\/p>\n<p>\u7d22\u5f15\u7684\u7279\u70b9<\/p>\n<p>\u6240\u6709\u7684MySQL\u5217\u7c7b\u578b\u80fd\u88ab\u7d22\u5f15\u3002\u5728\u76f8\u5173\u7684\u5217\u4e0a\u7684\u4f7f\u7528\u7d22\u5f15\u662f\u6539\u8fdbSELECT\u64cd\u4f5c\u6027\u80fd\u7684\u6700\u597d\u65b9\u6cd5\u3002<\/p>\n<p>\u4e00\u4e2a\u8868\u6700\u591a\u53ef\u670916\u4e2a\u7d22\u5f15\u3002\u6700\u5927\u7d22\u5f15\u957f\u5ea6\u662f256\u4e2a\u5b57\u8282\uff0c\u5c3d\u7ba1\u8fd9\u53ef\u4ee5\u5728\u7f16\u8bd1MySQL\u65f6\u88ab\u6539\u53d8\u3002<\/p>\n<p>\u5bf9\u4e8eCHAR\u548c VARCHAR\u5217\uff0c\u4f60\u53ef\u4ee5\u7d22\u5f15\u5217\u7684\u524d\u7f00\u3002\u8fd9\u66f4\u5feb\u5e76\u4e14\u6bd4\u7d22\u5f15\u6574\u4e2a\u5217\u9700\u8981\u8f83\u5c11\u7684\u78c1\u76d8\u7a7a\u95f4\u3002\u5bf9\u4e8eBLOB\u548cTEXT\u5217\uff0c\u4f60\u5fc5\u987b\u7d22\u5f15\u5217\u7684\u524d\u7f00\uff0c\u4f60\u4e0d\u80fd\u7d22\u5f15\u5217\u7684\u5168\u90e8\u3002<\/p>\n<p>MySQL\u80fd\u5728\u591a\u4e2a\u5217\u4e0a\u521b\u5efa\u7d22\u5f15\u3002\u4e00\u4e2a\u7d22\u5f15\u53ef\u4ee5\u7531\u6700\u591a15\u4e2a\u5217\u7ec4\u6210\u3002\uff08\u5728CHAR\u548cVARCHAR\u5217\u4e0a\uff0c\u4f60\u4e5f\u53ef\u4ee5\u4f7f\u7528\u5217\u7684\u524d\u7f00\u4f5c\u4e3a\u4e00\u4e2a\u7d22\u5f15\u7684\u90e8\u5206\uff09\u3002<\/p>\n<p>\u867d\u7136\u968f\u7740 MySQL \u7684\u8fdb\u4e00\u6b65\u5f00\u53d1\u521b\u5efa\u7d22\u5f15\u7684\u7ea6\u675f\u5c06\u4f1a\u8d8a\u6765\u8d8a\u5c11\uff0c\u4f46\u73b0\u5728\u8fd8\u662f\u5b58\u5728\u4e00\u4e9b\u7ea6\u675f\u7684\u3002\u4e0b\u9762\u7684\u8868\u6839\u636e\u7d22\u5f15\u7684\u7279\u6027\uff0c\u7ed9\u51fa\u4e86 ISAM \u8868\u548c MyISAM \u8868\u4e4b\u95f4\u7684\u5dee\u522b\uff1a<\/p>\n<p>\u88682-1 \u901a\u9053\u4fe1\u606f\u7279\u5f81\u5b57\u5bf9\u7167\u8868\u7d22\u5f15\u7684\u7279\u70b9 ISAM \u8868 MyISAM \u8868<\/p>\n<p>NULL \u503c<\/p>\n<p>BLOB \u548c TEXT \u5217<\/p>\n<p>\u6bcf\u4e2a\u8868\u4e2d\u7684\u7d22\u5f15\u6570<\/p>\n<p>\u6bcf\u4e2a\u7d22\u5f15\u4e2d\u7684\u5217\u6570<\/p>\n<p>\u6700\u5927\u7d22\u5f15\u884c\u5c3a\u5bf8<\/p>\n<p>\u4e0d\u5141\u8bb8<\/p>\n<p>\u4e0d\u80fd\u7d22\u5f15<\/p>\n<p>16<\/p>\n<p>16<\/p>\n<p>256 \u5b57\u8282 \u5141\u8bb8<\/p>\n<p>\u53ea\u80fd\u7d22\u5f15\u5217\u7684\u524d\u7f00<\/p>\n<p>32<\/p>\n<p>16<\/p>\n<p>500 \u5b57\u8282<\/p>\n<p>\u4ece\u6b64\u8868\u4e2d\u53ef\u4ee5\u770b\u5230\uff0c\u5bf9\u4e8e ISAM \u8868\u6765\u8bf4\uff0c\u5176\u7d22\u5f15\u5217\u5fc5\u987b\u5b9a\u4e49\u4e3a NOT NULL\uff0c\u5e76\u4e14\u4e0d\u80fd\u5bf9 BLOB \u548c TEXT \u5217\u8fdb\u884c\u7d22\u5f15\u3002MyISAM \u8868\u7c7b\u578b\u53bb\u6389\u4e86\u8fd9\u4e9b\u9650\u5236\uff0c\u800c\u4e14\u51cf\u7f13\u4e86\u5176\u4ed6\u7684\u4e00\u4e9b\u9650\u5236\u3002\u4e24\u79cd\u8868\u7c7b\u578b\u7684\u7d22\u5f15\u7279\u6027\u7684\u5dee\u5f02\u8868\u660e\uff0c\u6839\u636e\u6240\u4f7f\u7528\u7684 MySQL \u7248\u672c\u7684\u4e0d\u540c\uff0c\u6709\u53ef\u80fd\u5bf9\u67d0\u4e9b\u5217\u4e0d\u80fd\u8fdb\u884c\u7d22\u5f15\u3002\u4f8b\u5982\uff0c\u5982\u679c\u4f7f\u75283.23 \u7248\u4ee5\u524d\u7684\u7248\u672c\uff0c\u5219\u4e0d\u80fd\u5bf9\u5305\u542b NULL \u503c\u7684\u5217\u8fdb\u884c\u7d22\u5f15\u3002<\/p>\n<p>\u7d22\u5f15\u6709\u5982\u4e0b\u7684\u51e0\u79cd\u60c5\u51b5\uff1a<\/p>\n<p>INDEX\u7d22\u5f15\uff1a\u901a\u5e38\u610f\u4e49\u7684\u7d22\u5f15\uff0c\u67d0\u4e9b\u60c5\u51b5\u4e0bKEY\u662f\u5b83\u7684\u4e00\u4e2a\u540c\u4e49\u8bcd\u3002\u7d22\u5f15\u7684\u5217\u53ef\u4ee5\u5305\u62ec\u91cd\u590d\u7684\u503c\u3002<\/p>\n<p>UNIQUE\u7d22\u5f15\uff1a\u552f\u4e00\u7d22\u5f15\uff0c\u4fdd\u8bc1\u4e86\u5217\u4e0d\u5305\u542b\u91cd\u590d\u7684\u503c\uff0c\u5bf9\u4e8e\u591a\u5217\u552f\u4e00\u7d22\u5f15\uff0c\u5b83\u4fdd\u8bc1\u503c\u7684\u7ec4\u5408\u4e0d\u91cd\u590d\u3002<\/p>\n<p>PRIMARY KEY\u7d22\u5f15\uff1a\u4e5fUNIQUE\u7d22\u5f15\u975e\u5e38\u7c7b\u4f3c\u3002\u4e8b\u5b9e\u4e0a\uff0cPRIMARYKEY\u7d22\u5f15\u4ec5\u662f\u4e00\u4e2a\u5177\u6709PRIMARY\u540d\u79f0\u7684UNIQUE\u7d22\u5f15\u3002\u8fd9\u8868\u793a\u4e00\u4e2a\u8868\u53ea\u80fd\u5305\u542b\u4e00\u4e2aPRIMARY KEY\u3002<\/p>\n<p>\u7528Alter Table\u8bed\u53e5\u521b\u5efa\u4e0e\u5220\u9664\u7d22\u5f15<\/p>\n<p>\u4e3a\u4e86\u7ed9\u73b0\u6709\u7684\u8868\u589e\u52a0\u4e00\u4e2a\u7d22\u5f15\uff0c\u53ef\u4f7f\u7528 ALTER TABLE \u6216CREATE INDEX \u8bed\u53e5\u3002ALTER TABLE \u6700\u5e38\u7528\uff0c\u56e0\u4e3a\u53ef\u7528\u5b83\u6765\u521b\u5efa\u666e\u901a\u7d22\u5f15\u3001UNIQUE \u7d22\u5f15\u6216 PRIMARY KEY \u7d22\u5f15\uff0c\u5982\uff1a<\/p>\n<p>ALTER TABLE tbl_name ADD INDEX index_name\u00a0 (column_list)<\/p>\n<p>ALTER TABLE tbl_name ADD UNIQUE index_name\u00a0 (column_list)<\/p>\n<p>ALTER TABLE tbl_name ADD PRIMARY KEY index_name\u00a0 (column_list)<\/p>\n<p>\u5176\u4e2d tbl_name \u662f\u8981\u589e\u52a0\u7d22\u5f15\u7684\u8868\u540d\uff0c\u800c column_list \u6307\u51fa\u5bf9\u54ea\u4e9b\u5217\u8fdb\u884c\u7d22\u5f15\u3002\u4e00\u4e2a(col1,col2,&#8230;)\u5f62\u5f0f\u7684\u5217\u8868\u521b\u9020\u4e00\u4e2a\u591a\u5217\u7d22\u5f15\u3002\u7d22\u5f15\u503c\u6709\u7ed9\u5b9a\u5217\u7684\u503c\u4e32\u8054\u800c\u6210\u3002\u5982\u679c\u7d22\u5f15\u7531\u4e0d\u6b62\u4e00\u5217\u7ec4\u6210\uff0c\u5404\u5217\u540d\u4e4b\u95f4\u7528\u9017\u53f7\u5206\u9694\u3002\u7d22\u5f15\u540d index_name \u662f\u53ef\u9009\u7684\uff0c\u56e0\u6b64\u53ef\u4ee5\u4e0d\u5199\u5b83\uff0cMySQL \u5c06\u6839\u636e\u7b2c\u4e00\u4e2a\u7d22\u5f15\u5217\u8d4b\u7ed9\u5b83\u4e00\u4e2a\u540d\u79f0\u3002ALTER TABLE \u5141\u8bb8\u5728\u5355\u4e2a\u8bed\u53e5\u4e2d\u6307\u5b9a\u591a\u4e2a\u8868\u7684\u66f4\u6539\uff0c\u56e0\u6b64\u53ef\u4ee5\u5728\u540c\u65f6\u521b\u5efa\u591a\u4e2a\u7d22\u5f15\u3002<\/p>\n<p>\u540c\u6837\uff0c\u4e5f\u53ef\u4ee5\u7528ALTER TABLE\u8bed\u53e5\u5220\u9664\u5217\u7684\u7d22\u5f15\uff1a<\/p>\n<p>ALTER TABLE tbl_name DROP INDEX index_name<\/p>\n<p>ALTER TABLE tbl_name DROP PRIMARY KEY<\/p>\n<p>\u6ce8\u610f\u4e0a\u9762\u7b2c\u4e00\u6761\u8bed\u53e5\u53ef\u4ee5\u7528\u6765\u5220\u9664\u5404\u79cd\u7c7b\u578b\u7684\u7d22\u5f15\uff0c\u800c\u7b2c\u4e09\u6761\u8bed\u53e5\u53ea\u5728\u5220\u9664 PRIMARY KEY \u7d22\u5f15\u65f6\u4f7f\u7528\uff1b\u5728\u6b64\u60c5\u5f62\u4e2d\uff0c\u4e0d\u9700\u8981\u7d22\u5f15\u540d\uff0c\u56e0\u4e3a\u4e00\u4e2a\u8868\u53ea\u53ef\u80fd\u5177\u6709\u4e00\u4e2a\u8fd9\u6837\u7684\u7d22\u5f15\u3002\u5982\u679c\u6ca1\u6709\u660e\u786e\u5730\u521b\u5efa\u4f5c\u4e3a PRIMARY KEY \u7684\u7d22\u5f15\uff0c\u4f46\u8be5\u8868\u5177\u6709\u4e00\u4e2a\u6216\u591a\u4e2a UNIQUE \u7d22\u5f15\uff0c\u5219 MySQL \u5c06\u5220\u9664\u8fd9\u4e9b UNIQUE \u7d22\u5f15\u4e2d\u7684\u7b2c\u4e00\u4e2a\u3002<\/p>\n<p>\u5982\u679c\u4ece\u8868\u4e2d\u5220\u9664\u4e86\u5217\uff0c\u5219\u7d22\u5f15\u53ef\u80fd\u4f1a\u53d7\u5230\u5f71\u54cd\u3002\u5982\u679c\u6240\u5220\u9664\u7684\u5217\u4e3a\u7d22\u5f15\u7684\u7ec4\u6210\u90e8\u5206\uff0c\u5219\u8be5\u5217\u4e5f\u4f1a\u4ece\u7d22\u5f15\u4e2d\u5220\u9664\u3002\u5982\u679c\u7ec4\u6210\u7d22\u5f15\u7684\u6240\u6709\u5217\u90fd\u88ab\u5220\u9664\uff0c\u5219\u6574\u4e2a\u7d22\u5f15\u5c06\u88ab\u5220\u9664\u3002<\/p>\n<p>\u4f8b\u5982\uff0c\u5bf9\u4e8e\u4e0a\u9762\u6240\u4f7f\u7528\u7684student\u4e3a\u4f8b\uff0c\u4f60\u53ef\u80fd\u60f3\u4e3a\u4e4b\u521b\u5efa\u8fd9\u6837\u7684\u7d22\u5f15\uff0c\u4ee5\u52a0\u901f\u8868\u7684\u68c0\u7d22\u901f\u5ea6\uff1a<\/p>\n<p>mysql> ALTER TABLE student<\/p>\n<p>-> ADD PRIMARY KEY(id),<\/p>\n<p>-> ADD INDEXmark(english,Chinese,history);<\/p>\n<p>\u8fd9\u4e2a\u4f8b\u5b50\uff0c\u65e2\u5305\u62ecPRIMARY\u7d22\u5f15\uff0c\u4e5f\u5305\u62ec\u591a\u5217\u7d22\u5f15\u3002\u8bb0\u4f4f\uff0c\u4f7f\u7528 PRIMARY\u7d22\u5f15\u7684\u5217\uff0c\u5fc5\u987b\u662f\u4e00\u4e2a\u5177\u6709NOT NULL\u5c5e\u6027\u7684\u5217\uff0c\u5982\u679c\u4f60\u613f\u610f\u67e5\u770b\u521b\u5efa\u7684\u7d22\u5f15\u7684\u60c5\u51b5\uff0c\u53ef\u4ee5\u4f7f\u7528SHOW INDEX\u8bed\u53e5\uff1a<\/p>\n<p>mysql> SHOW INDEX FROM student;<\/p>\n<p>\u5176\u7ed3\u679c\u4e3a\uff1a<\/p>\n<p>+&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+-<\/p>\n<p>| Table\u00a0\u00a0| Non_unique | Key_name | Seq_in_index | Column_name |<\/p>\n<p>+&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+-<\/p>\n<p>| student |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0 | PRIMARY \u00a0|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a01 | id\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |<\/p>\n<p>| student |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | mark\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | english\u00a0\u00a0\u00a0\u00a0 |<\/p>\n<p>| student |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | mark\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 | chinese\u00a0\u00a0\u00a0\u00a0 |<\/p>\n<p>| student |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | mark\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 3 | history \u00a0\u00a0\u00a0\u00a0|<\/p>\n<p>+&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+-<\/p>\n<p>\u7531\u4e8e\u5217\u6570\u592a\u591a\uff0c\u4e0a\u8868\u5e76\u6ca1\u6709\u5305\u62ec\u6240\u6709\u7684\u8f93\u51fa\uff0c\u8bfb\u8005\u53ef\u4ee5\u8bd5\u7740\u81ea\u5df1\u67e5\u770b\u3002<\/p>\n<p>\u518d\u4f7f\u7528ALTER TABLE\u8bed\u53e5\u5220\u9664\u7d22\u5f15\uff0c\u5220\u9664\u7d22\u5f15\u9700\u8981\u77e5\u9053\u7d22\u5f15\u7684\u540d\u5b57\uff0c\u4f60\u53ef\u4ee5\u901a\u8fc7SHOW INDEX\u8bed\u53e5\u5f97\u5230\uff1a<\/p>\n<p>mysql> ALTER TABLE student DROP PRIMARYKEY,<\/p>\n<p>-> DROP INDEX mark;<\/p>\n<p>\u518d\u4ea7\u770b\u8868\u4e2d\u7684\u7d22\u5f15\uff0c\u5176\u8bed\u53e5\u548c\u8f93\u51fa\u4e3a\uff1a<\/p>\n<p>mysql> SHOW INDEX FROM student;<\/p>\n<p>Empty set (0.01 sec)<\/p>\n<p>\u7528CREATE\\DROP INDEX\u521b\u5efa\u7d22\u5f15<\/p>\n<p>\u8fd8\u53ef\u4ee5\u7528CREATE INDEX\u8bed\u53e5\u6765\u521b\u5efa\u7d22\u5f15.CREATE INDEX \u662f\u5728 MySQL 3.23\u7248\u4e2d\u5f15\u5165\u7684\uff0c\u4f46\u5982\u679c\u4f7f\u75283.23 \u7248\u4ee5\u524d\u7684\u7248\u672c\uff0c\u53ef\u5229\u7528 ALTER TABLE \u8bed\u53e5\u521b\u5efa\u7d22\u5f15\uff08MySQL \u901a\u5e38\u5728\u5185\u90e8\u5c06 CREATE INDEX \u6620\u5c04\u5230 ALTER TABLE\uff09\u3002\u8be5\u8bed\u53e5\u521b\u5efa\u7d22\u5f15\u7684\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n<p>CREATE UNIQUE INDEX index_name ON tbl_name(column_list)<\/p>\n<p>CREATE INDEX index_name ON tbl_name(column_list) tbl_name\u3001index_name \u548c column_list \u5177\u6709\u4e0e ALTER TABLE \u8bed\u53e5\u4e2d\u76f8\u540c\u7684\u542b\u4e49\u3002\u8fd9\u91cc\u7d22\u5f15\u540d\u4e0d\u53ef\u9009\u3002\u5f88\u660e\u663e\uff0cCREATE INDEX \u53ef\u5bf9\u8868\u589e\u52a0\u666e\u901a\u7d22\u5f15\u6216 UNIQUE \u7d22\u5f15\uff0c\u4e0d\u80fd\u7528 CREATE INDEX \u8bed\u53e5\u521b\u5efa PRIMARY KEY \u7d22\u5f15\u3002<\/p>\n<p>\u53ef\u5229\u7528 DROP INDEX\u8bed\u53e5\u6765\u5220\u9664\u7d22\u5f15\u3002\u7c7b\u4f3c\u4e8e CREATE INDEX \u8bed\u53e5\uff0cDROP INDEX \u901a\u5e38\u5728\u5185\u90e8\u4f5c\u4e3a\u4e00\u6761 ALTER TABLE \u8bed\u53e5\u5904\u7406\uff0c\u5e76\u4e14DROP INDEX\u662f\u5728 MySQL 3.22 \u4e2d\u5f15\u5165\u7684\u3002<\/p>\n<p>\u5220\u9664\u7d22\u5f15\u8bed\u53e5\u7684\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n<p>DROP INDEX index_name ON tbl_name<\/p>\n<p>\u8fd8\u662f\u4e0a\u4e00\u8282\u7684\u4f8b\u5b50\uff0c\u7531\u4e8eCREATE INDEX\u4e0d\u80fd\u521b\u5efaPRIMARY\u7d22\u5f15\uff0c\u6240\u4ee5\u8fd9\u91cc\u6211\u4eec\u53ea\u521b\u5efa\u4e00\u4e2a\u591a\u5217\u7d22\u5f15\uff1a<\/p>\n<p>mysql> CREATE INDEX mark ONstudent(english,chinese,history);<\/p>\n<p>\u540c\u6837\u7684\u68c0\u67e5student\u8868\uff0c\u53ef\u77e5\uff1a<\/p>\n<p>mysql> SHOW INDEX FROM student;<\/p>\n<p>+&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+<\/p>\n<p>| Table\u00a0\u00a0| Non_unique | Key_name | Seq_in_index | Column_name |<\/p>\n<p>+&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+<\/p>\n<p>| student |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | mark\u00a0\u00a0 \u00a0\u00a0|\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a01 | english\u00a0\u00a0\u00a0\u00a0 |<\/p>\n<p>| student |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | mark\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 | chinese\u00a0\u00a0\u00a0\u00a0 |<\/p>\n<p>| student |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | mark\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 3 | history\u00a0\u00a0\u00a0\u00a0 |<\/p>\n<p>+&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+<\/p>\n<p>\u7136\u540e\u4f7f\u7528\u4e0b\u9762\u7684\u8bed\u53e5\u5220\u9664\u7d22\u5f15\uff1a<\/p>\n<p>mysql> DROP INDEX mark ON student;<\/p>\n<p>\u5728\u521b\u5efa\u8868\u65f6\u6307\u5b9a\u7d22\u5f15<\/p>\n<p>\u8981\u60f3\u5728\u53d1\u5e03 CREATE TABLE \u8bed\u53e5\u65f6\u4e3a\u65b0\u8868\u521b\u5efa\u7d22\u5f15\uff0c\u6240\u4f7f\u7528\u7684\u8bed\u6cd5\u7c7b\u4f3c\u4e8e ALTER TABLE \u8bed\u53e5\u7684\u8bed\u6cd5\uff0c\u4f46\u662f\u5e94\u8be5\u5728\u60a8\u5b9a\u4e49\u8868\u5217\u7684\u8bed\u53e5\u90e8\u5206\u6307\u5b9a\u7d22\u5f15\u521b\u5efa\u5b50\u53e5\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<div class=\"dp-highlighter bg_sql\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[sql]<\/strong> <a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">copy<\/a>\n<div><embed id=\"ZeroClipboardMovie_5\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_5\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-sql\" start=\"1\">\n    <li class=\"alt\"><span class=\"keyword\">CREATE<\/span>\u00a0<span class=\"keyword\">TABLE<\/span>\u00a0tbl_name<\/li>\n    <li>(<\/li>\n    <li class=\"alt\">\u2026<\/li>\n    <li><span class=\"keyword\">INDEX<\/span>\u00a0index_name\u00a0(column_list),<\/li>\n    <li class=\"alt\"><span class=\"keyword\">KEY<\/span>\u00a0index_name\u00a0(column_list),<\/li>\n    <li><span class=\"keyword\">UNIQUE<\/span>\u00a0index_name\u00a0(column_list),<\/li>\n    <li class=\"alt\"><span class=\"keyword\">PRIMARY<\/span>\u00a0<span class=\"keyword\">KEY<\/span>\u00a0index_name\u00a0(column_list),<\/li>\n    <li>\u2026<\/li>\n    <li class=\"alt\">)<\/li>\n<\/ol>\n<\/div>\n<p>\u4e0eALTER TABLE \u4e00\u6837\uff0c\u7d22\u5f15\u540d\u5bf9\u4e8e INDEX \u548c UNIQUE \u90fd\u662f\u53ef\u9009\u7684\uff0c\u5982\u679c\u672a\u7ed9\u51fa\uff0cMySQL \u5c06\u4e3a\u5176\u9009\u4e00\u4e2a\u3002\u53e6\u5916\uff0c\u8fd9\u91ccKEY\u65f6INDEX\u7684\u4e00\u4e2a\u522b\u540d\uff0c\u5177\u6709\u76f8\u540c\u7684\u610f\u4e49\u3002<\/p>\n<p>\u6709\u4e00\u79cd\u7279\u6b8a\u60c5\u5f62\uff1a\u53ef\u5728\u5217\u5b9a\u4e49\u4e4b\u540e\u589e\u52a0 PRIMARY KEY \u521b\u5efa\u4e00\u4e2a\u5355\u5217\u7684PRIMARY KEY \u7d22\u5f15\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<div class=\"dp-highlighter bg_sql\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[sql]<\/strong> <a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">copy<\/a>\n<div><embed id=\"ZeroClipboardMovie_6\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_6\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-sql\" start=\"1\">\n    <li class=\"alt\"><span class=\"keyword\">CREATE<\/span>\u00a0<span class=\"keyword\">TABLE<\/span>\u00a0tbl_name<\/li>\n    <li>(<\/li>\n    <li class=\"alt\">\u00a0\u00a0iINT\u00a0<span class=\"op\">NOT<\/span>\u00a0<span class=\"op\">NULL<\/span>\u00a0<span class=\"keyword\">PRIMARY<\/span>\u00a0<span class=\"keyword\">KEY<\/span><\/li>\n    <li>)<\/li>\n<\/ol>\n<\/div>\n<p>\u8be5\u8bed\u53e5\u7b49\u4ef7\u4e8e\u4ee5\u4e0b\u7684\u8bed\u53e5:<\/p>\n<div class=\"dp-highlighter bg_sql\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[sql]<\/strong> <a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">copy<\/a>\n<div><embed id=\"ZeroClipboardMovie_7\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_7\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-sql\" start=\"1\">\n    <li class=\"alt\"><span class=\"keyword\">CREATE<\/span>\u00a0<span class=\"keyword\">TABLE<\/span>\u00a0tbl_name<\/li>\n    <li>(<\/li>\n    <li class=\"alt\">\u00a0\u00a0iINT\u00a0<span class=\"op\">NOT<\/span>\u00a0<span class=\"op\">NULL<\/span>,<\/li>\n    <li>\u00a0<span class=\"keyword\">PRIMARY<\/span>\u00a0<span class=\"keyword\">KEY<\/span>\u00a0(i)<\/li>\n    <li class=\"alt\">)<\/li>\n<\/ol>\n<\/div>\n<p>\u524d\u9762\u6240\u6709\u8868\u521b\u5efa\u6837\u4f8b\u90fd\u5bf9\u7d22\u5f15\u5217\u6307\u5b9a\u4e86 NOT NULL\u3002\u5982\u679c\u662f ISAM \u8868\uff0c\u8fd9\u662f\u5fc5\u987b\u7684\uff0c\u56e0\u4e3a\u4e0d\u80fd\u5bf9\u53ef\u80fd\u5305\u542b NULL \u503c\u7684\u5217\u8fdb\u884c\u7d22\u5f15\u3002\u5982\u679c\u662f MyISAM \u8868\uff0c\u7d22\u5f15\u5217\u53ef\u4ee5\u4e3a NULL\uff0c\u53ea\u8981\u8be5\u7d22\u5f15\u4e0d\u662f PRIMARY KEY \u7d22\u5f15\u5373\u53ef\u3002<\/p>\n<p>\u5728CREATE TBALE\u8bed\u53e5\u4e2d\u53ef\u4ee5\u67d0\u4e2a\u4e32\u5217\u7684\u524d\u7f00\u8fdb\u884c\u7d22\u5f15\uff08\u5217\u503c\u7684\u6700\u5de6\u8fb9 n \u4e2a\u5b57\u7b26\uff09\u3002<\/p>\n<p>\u5982\u679c\u5bf9\u67d0\u4e2a\u4e32\u5217\u7684\u524d\u7f00\u8fdb\u884c\u7d22\u5f15\uff0c\u5e94\u7528 column_list \u8bf4\u660e\u7b26\u8868\u793a\u8be5\u5217\u7684\u8bed\u6cd5\u4e3a col_name(n) \u800c\u4e0d\u7528col_name\u3002\u4f8b\u5982\uff0c\u4e0b\u9762\u7b2c\u4e00\u6761\u8bed\u53e5\u521b\u5efa\u4e86\u4e00\u4e2a\u5177\u6709\u4e24\u4e2a CHAR \u5217\u7684\u8868\u548c\u4e00\u4e2a\u7531\u8fd9\u4e24\u5217\u7ec4\u6210\u7684\u7d22\u5f15\u3002\u7b2c\u4e8c\u6761\u8bed\u53e5\u7c7b\u4f3c\uff0c\u4f46\u53ea\u5bf9\u6bcf\u4e2a\u5217\u7684\u524d\u7f00\u8fdb\u884c\u7d22\u5f15\uff1a<\/p>\n<div class=\"dp-highlighter bg_sql\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[sql]<\/strong> <a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">copy<\/a>\n<div><embed id=\"ZeroClipboardMovie_8\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_8\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-sql\" start=\"1\">\n    <li class=\"alt\"><span class=\"keyword\">CREATE<\/span>\u00a0<span class=\"keyword\">TABLE<\/span>\u00a0tbl_name<\/li>\n    <li>(<\/li>\n    <li class=\"alt\"><span class=\"keyword\">name<\/span>\u00a0<span class=\"keyword\">CHAR<\/span>(30),<\/li>\n    <li>address\u00a0<span class=\"keyword\">CHAR<\/span>(60),<\/li>\n    <li class=\"alt\"><span class=\"keyword\">INDEX<\/span>\u00a0(<span class=\"keyword\">name<\/span>,address)<\/li>\n    <li>)<\/li>\n<\/ol>\n<\/div>\n<div class=\"dp-highlighter bg_sql\">\n<div class=\"bar\">\n<div class=\"tools\"><strong>[sql]<\/strong> <a class=\"ViewSource\" title=\"view plain\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">view plain<\/a>\n<a class=\"CopyToClipboard\" title=\"copy\" href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482#\">copy<\/a>\n<div><embed id=\"ZeroClipboardMovie_9\" src=\"http:\/\/static.blog.csdn.net\/scripts\/ZeroClipboard\/ZeroClipboard.swf\" type=\"application\/x-shockwave-flash\" width=\"18\" height=\"18\" align=\"middle\" name=\"ZeroClipboardMovie_9\"><\/embed><\/div>\n<\/div>\n<\/div>\n<ol class=\"dp-sql\" start=\"1\">\n    <li class=\"alt\"><span class=\"keyword\">CREATE<\/span>\u00a0<span class=\"keyword\">TABLE<\/span>\u00a0tbl_name<\/li>\n    <li>(<\/li>\n    <li class=\"alt\"><span class=\"keyword\">name<\/span>\u00a0<span class=\"keyword\">CHAR<\/span>(30),<\/li>\n    <li>address\u00a0<span class=\"keyword\">CHAR<\/span>(60),<\/li>\n    <li class=\"alt\"><span class=\"keyword\">INDEX<\/span>\u00a0(<span class=\"keyword\">name<\/span>(10),address(20))<\/li>\n    <li>)<\/li>\n<\/ol>\n<\/div>\n<p>\u4f60\u53ef\u4ee5\u68c0\u67e5\u6240\u521b\u5efa\u8868\u7684\u7d22\u5f15\uff1a<\/p>\n<p>mysql> SHOW INDEX FROM tbl_name;<\/p>\n<p>+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+-<\/p>\n<p>| Table\u00a0\u00a0\u00a0| Non_unique | Key_name | Seq_in_index | Column_name |<\/p>\n<p>+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+-<\/p>\n<p>| tbl_name |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | name\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | name\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 |<\/p>\n<p>| tbl_name |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1 | name\u00a0\u00a0\u00a0\u00a0 |\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2 | address\u00a0\u00a0\u00a0\u00a0 |<\/p>\n<p>+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;+&#8212;&#8212;&#8212;-+&#8212;&#8212;&#8212;&#8212;&#8211;+&#8212;&#8212;&#8212;&#8212;-+-<\/p>\n<p>\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u53ef\u80fd\u4f1a\u53d1\u73b0\u5fc5\u987b\u5bf9\u5217\u7684\u524d\u7f00\u8fdb\u884c\u7d22\u5f15\u3002\u4f8b\u5982\uff0c\u7d22\u5f15\u884c\u7684\u957f\u5ea6\u6709\u4e00\u4e2a\u6700\u5927\u4e0a\u9650\uff0c\u56e0\u6b64\uff0c\u5982\u679c\u7d22\u5f15\u5217\u7684\u957f\u5ea6\u8d85\u8fc7\u4e86\u8fd9\u4e2a\u4e0a\u9650\uff0c\u90a3\u4e48\u5c31\u53ef\u80fd\u9700\u8981\u5229\u7528\u524d\u7f00\u8fdb\u884c\u7d22\u5f15\u3002\u5728 MyISAM \u8868\u7d22\u5f15\u4e2d\uff0c\u5bf9 BLOB \u6216 TEXT \u5217\u4e5f\u9700\u8981\u524d\u7f00\u7d22\u5f15\u3002<\/p>\n<p>\u5bf9\u4e00\u4e2a\u5217\u7684\u524d\u7f00\u8fdb\u884c\u7d22\u5f15\u9650\u5236\u4e86\u4ee5\u540e\u5bf9\u8be5\u5217\u7684\u66f4\u6539\uff1b\u4e0d\u80fd\u5728\u4e0d\u5220\u9664\u8be5\u7d22\u5f15\u5e76\u4f7f\u7528\u8f83\u77ed\u524d\u7f00\u7684\u60c5\u51b5\u4e0b\uff0c\u5c06\u8be5\u5217\u7f29\u77ed\u4e3a\u4e00\u4e2a\u957f\u5ea6\u5c0f\u4e8e\u7d22\u5f15\u6240\u7528\u524d\u7f00\u7684\u957f\u5ea6\u7684\u5217\u3002<\/p>\n<p>\u603b\u7ed3<\/p>\n<p>\u672c\u8282\u5bf9\u7d22\u5f15\u7684\u7c7b\u578b\uff0c\u5df2\u7ecf\u5982\u4f55\u521b\u5efa\u7d22\u5f15\u505a\u4e86\u4ecb\u7ecd\uff0c\u5176\u4e2d\u6d89\u53ca\u4e09\u4e2a\u6bd4\u8f83\u91cd\u8981\u7684SQL\u8bed\u53e5\u2015\u2015ALTER TABLE\u3001CREATE\/DROP INDEX\u548cCREATE TABLE\uff0c\u6ce8\u610f\u5b83\u4eec\u7684\u7528\u6cd5\u3002<\/p>\n<p>\u7d22\u5f15\u6700\u91cd\u8981\u7684\u529f\u80fd\u662f\uff0c\u901a\u8fc7\u4f7f\u7528\u7d22\u5f15\u52a0\u901f\u8868\u7684\u68c0\u7d22\uff0c\u6709\u5173\u8fd9\u65b9\u9762\u7684\u77e5\u8bc6\uff0c\u5c06\u5728\u7b2c\u5341\u7ae0\u6570\u636e\u5e93\u4f18\u5316\u4e2d\u4ecb\u7ecd\u3002<\/p>\n<p>\u601d\u8003\u9898<\/p>\n<p>1\u3001\u5efa\u7acb\u4e00\u4e2a\u5982\u4e0b\u6240\u8ff0\u7684\u8868\uff1a<\/p>\n<p>data\uff1aFLOAT\u5217\uff0c\u4f7f\u7528\u968f\u673a\u51fd\u6570\u586b\u5145\u6570\u636e<\/p>\n<p>birth\uff1aDATETIME\u5217\uff0c\u586b\u5145\u5f53\u524d\u65f6\u95f4\u3002<\/p>\n<p>\u7136\u540e\uff0c\u8bf7\u5f55\u5165\u51e0\u6761\u6570\u636e\u3002\u6700\u540e\u8ba1\u7b97data\u5217\u7684\u5e73\u5747\u503c\u3001\u603b\u548c\u3001\u6781\u503c\uff0c\u5e76\u4e14\u6309\u7167data\u5217\u964d\u5e8f\u6392\u5e8f\u68c0\u7d22\u503c\u3002<\/p>\n<p>2\u3001\u5206\u522b\u4f7f\u7528\u6807\u51c6SQL\u6a21\u5f0f\u548c\u6269\u5c55\u6b63\u89c4\u8868\u8fbe\u5f0f\u6a21\u5f0f\u5339\u914d\uff0c\u5339\u914d\u4e0a\u9762\u521b\u5efa\u7684\u8868\uff0c\u5047\u8bbe\u4f60\u521b\u5efa\u8868\u7684\u5f53\u524d\u65e5\u671f\u4e3a2001-01-01\uff0c\u7528\u6a21\u5f0f\u5339\u914d\u68c0\u7d22\u51fabirth\u5217\u5305\u542b\u8be5\u65e5\u671f\u7684\u503c\u3002\uff08\u5b9e\u9645\u4e0a\uff0c\u4e0a\u9762\u7684\u8868\u4e2d\u8bb0\u5f55\u90fd\u662f\u540c\u4e00\u65e5\u671f\u5f55\u5165\u7684\uff0c\u56e0\u6b64\u5b9e\u9645\u5c06\u8fd4\u56de\u5168\u90e8\u8bb0\u5f55\u3002\uff09<\/p>\n<p>3\u3001\u4e3a\u524d\u51e0\u7ae0\u4f7f\u7528\u7684\u6570\u636e\u8868\u521b\u5efa\u7d22\u5f15\uff1a<\/p>\n<p>student\uff1a\u4e3aid\u6bb5\u521b\u5efa\u4e00\u4e2aPRIMARY\u7d22\u5f15\uff0c\u4e3aenglish\u3001chinese\u548chistory\u521b\u5efa\u4e00\u4e2a\u591a\u5217\u7d22\u5f15\u3002<\/p>\n<p>pet\uff1a\u4e3aname\u548cowner\u6bb5\u521b\u5efa\u4e00\u4e2a\u591a\u7c7b\u7d22\u5f15\u3002<\/p>\n<p>4\u3001\u5220\u9664\u4e3apet\u8868\u521b\u5efa\u7684\u7d22\u5f15\u3002<\/p>\n<p>##################################################<\/p>\n<p><strong>MySQL Index\u7684\u4f7f\u7528<\/strong><\/p>\n<p>\u4ee5\u4e0b\u662f\u7406\u8bba\u77e5\u8bc6\u5907\u5fd8\uff1a<\/p>\n<p>\u4e00\u3001\u4ec0\u4e48\u662f\u7d22\u5f15\uff1f\n\u7d22\u5f15\u7528\u6765\u5feb\u901f\u5730\u5bfb\u627e\u90a3\u4e9b\u5177\u6709\u7279\u5b9a\u503c\u7684\u8bb0\u5f55\uff0c\u6240\u6709MySQL\u7d22\u5f15\u90fd\u4ee5B-\u6811\u7684\u5f62\u5f0f\u4fdd\u5b58\u3002\u5982\u679c\u6ca1\u6709\u7d22\u5f15\uff0c\u6267\u884c\u67e5\u8be2\u65f6MySQL\u5fc5\u987b\u4ece\u7b2c\u4e00\u4e2a\u8bb0\u5f55\u5f00\u59cb\u626b\u63cf\u6574\u4e2a\u8868\u7684\u6240\u6709\u8bb0\u5f55\uff0c\u76f4\u81f3\u627e\u5230\u7b26\u5408\u8981\u6c42\u7684\u8bb0\u5f55\u3002\u8868\u91cc\u9762\u7684\u8bb0\u5f55\u6570\u91cf\u8d8a\u591a\uff0c\u8fd9\u4e2a\u64cd\u4f5c\u7684\u4ee3\u4ef7\u5c31\u8d8a\u9ad8\u3002\u5982\u679c\u4f5c\u4e3a\u641c\u7d22\u6761\u4ef6\u7684\u5217\u4e0a\u5df2\u7ecf\u521b\u5efa\u4e86\u7d22\u5f15\uff0cMySQL\u65e0\u9700\u626b\u63cf\u4efb\u4f55\u8bb0\u5f55\u5373\u53ef\u8fc5\u901f\u5f97\u5230\u76ee\u6807\u8bb0\u5f55\u6240\u5728\u7684\u4f4d\u7f6e\u3002\u5982\u679c\u8868\u67091000\u4e2a\u8bb0\u5f55\uff0c\u901a\u8fc7\u7d22\u5f15\u67e5\u627e\u8bb0\u5f55\u81f3\u5c11\u8981\u6bd4\u987a\u5e8f\u626b\u63cf\u8bb0\u5f55\u5feb100\u500d\u3002<\/p>\n<p>\u5047\u8bbe\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u540d\u4e3apeople\u7684\u8868\uff1a<\/p>\n<p>CREATE TABLE people ( peopleid SMALLINT NOT NULL, name CHAR(50) NOT NULL );<\/p>\n<p>\u7136\u540e\uff0c\u6211\u4eec\u5b8c\u5168\u968f\u673a\u628a1000\u4e2a\u4e0d\u540cname\u503c\u63d2\u5165\u5230people\u8868\u3002\u4e0b\u56fe\u663e\u793a\u4e86people\u8868\u6240\u5728\u6570\u636e\u6587\u4ef6\u7684\u4e00\u5c0f\u90e8\u5206\uff1a<\/p>\n<p>\u53ef\u4ee5\u770b\u5230\uff0c\u5728\u6570\u636e\u6587\u4ef6\u4e2dname\u5217\u6ca1\u6709\u4efb\u4f55\u660e\u786e\u7684\u6b21\u5e8f\u3002\u5982\u679c\u6211\u4eec\u521b\u5efa\u4e86name\u5217\u7684\u7d22\u5f15\uff0cMySQL\u5c06\u5728\u7d22\u5f15\u4e2d\u6392\u5e8fname\u5217\uff1a<\/p>\n<p>\u5bf9\u4e8e\u7d22\u5f15\u4e2d\u7684\u6bcf\u4e00\u9879\uff0cMySQL\u5728\u5185\u90e8\u4e3a\u5b83\u4fdd\u5b58\u4e00\u4e2a\u6570\u636e\u6587\u4ef6\u4e2d\u5b9e\u9645\u8bb0\u5f55\u6240\u5728\u4f4d\u7f6e\u7684\u201c\u6307\u9488\u201d\u3002\u56e0\u6b64\uff0c\u5982\u679c\u6211\u4eec\u8981\u67e5\u627ename\u7b49\u4e8e\u201cMike\u201d\u8bb0\u5f55\u7684 peopleid\uff08SQL\u547d\u4ee4\u4e3a\u201cSELECT peopleid FROM people WHERE name=&#8217;Mike&#8217;;\u201d\uff09\uff0cMySQL\u80fd\u591f\u5728name\u7684\u7d22\u5f15\u4e2d\u67e5\u627e\u201cMike\u201d\u503c\uff0c\u7136\u540e\u76f4\u63a5\u8f6c\u5230\u6570\u636e\u6587\u4ef6\u4e2d\u76f8\u5e94\u7684\u884c\uff0c\u51c6\u786e\u5730\u8fd4\u56de\u8be5\u884c\u7684 peopleid\uff08999\uff09\u3002\u5728\u8fd9\u4e2a\u8fc7\u7a0b\u4e2d\uff0cMySQL\u53ea\u9700\u5904\u7406\u4e00\u4e2a\u884c\u5c31\u53ef\u4ee5\u8fd4\u56de\u7ed3\u679c\u3002\u5982\u679c\u6ca1\u6709\u201cname\u201d\u5217\u7684\u7d22\u5f15\uff0cMySQL\u8981\u626b\u63cf\u6570\u636e\u6587\u4ef6\u4e2d\u7684\u6240\u6709\u8bb0\u5f55\uff0c\u53731000\u4e2a\u8bb0\u5f55\uff01\u663e\u7136\uff0c\u9700\u8981MySQL\u5904\u7406\u7684\u8bb0\u5f55\u6570\u91cf\u8d8a\u5c11\uff0c\u5219\u5b83\u5b8c\u6210\u4efb\u52a1\u7684\u901f\u5ea6\u5c31\u8d8a\u5feb\u3002<\/p>\n<p>\u4e8c\u3001\u7d22\u5f15\u7684\u7c7b\u578b\nMySQL\u63d0\u4f9b\u591a\u79cd\u7d22\u5f15\u7c7b\u578b\u4f9b\u9009\u62e9\uff1a<\/p>\n<p>\u666e\u901a\u7d22\u5f15\n\u8fd9\u662f\u6700\u57fa\u672c\u7684\u7d22\u5f15\u7c7b\u578b\uff0c\u800c\u4e14\u5b83\u6ca1\u6709\u552f\u4e00\u6027\u4e4b\u7c7b\u7684\u9650\u5236\u3002\u666e\u901a\u7d22\u5f15\u53ef\u4ee5\u901a\u8fc7\u4ee5\u4e0b\u51e0\u79cd\u65b9\u5f0f\u521b\u5efa\uff1a\n\u521b\u5efa\u7d22\u5f15\uff0c\u4f8b\u5982CREATE INDEX <\u7d22\u5f15\u7684\u540d\u5b57> ON tablename (\u5217\u7684\u5217\u8868);\n\u4fee\u6539\u8868\uff0c\u4f8b\u5982ALTER TABLE tablename ADD INDEX [\u7d22\u5f15\u7684\u540d\u5b57] (\u5217\u7684\u5217\u8868);\n\u521b\u5efa\u8868\u7684\u65f6\u5019\u6307\u5b9a\u7d22\u5f15\uff0c\u4f8b\u5982CREATE TABLE tablename ( [&#8230;], INDEX [\u7d22\u5f15\u7684\u540d\u5b57] (\u5217\u7684\u5217\u8868) );<\/p>\n<p>\u552f\u4e00\u6027\u7d22\u5f15\n\u8fd9\u79cd\u7d22\u5f15\u548c\u524d\u9762\u7684\u201c\u666e\u901a\u7d22\u5f15\u201d\u57fa\u672c\u76f8\u540c\uff0c\u4f46\u6709\u4e00\u4e2a\u533a\u522b\uff1a\u7d22\u5f15\u5217\u7684\u6240\u6709\u503c\u90fd\u53ea\u80fd\u51fa\u73b0\u4e00\u6b21\uff0c\u5373\u5fc5\u987b\u552f\u4e00\u3002\u552f\u4e00\u6027\u7d22\u5f15\u53ef\u4ee5\u7528\u4ee5\u4e0b\u51e0\u79cd\u65b9\u5f0f\u521b\u5efa\uff1a\n\u521b\u5efa\u7d22\u5f15\uff0c\u4f8b\u5982CREATE UNIQUE INDEX <\u7d22\u5f15\u7684\u540d\u5b57> ON tablename (\u5217\u7684\u5217\u8868);\n\u4fee\u6539\u8868\uff0c\u4f8b\u5982ALTER TABLE tablename ADD UNIQUE [\u7d22\u5f15\u7684\u540d\u5b57] (\u5217\u7684\u5217\u8868);\n\u521b\u5efa\u8868\u7684\u65f6\u5019\u6307\u5b9a\u7d22\u5f15\uff0c\u4f8b\u5982CREATE TABLE tablename ( [&#8230;], UNIQUE [\u7d22\u5f15\u7684\u540d\u5b57] (\u5217\u7684\u5217\u8868) );<\/p>\n<p>\u4e3b\u952e\n\u4e3b\u952e\u662f\u4e00\u79cd\u552f\u4e00\u6027\u7d22\u5f15\uff0c\u4f46\u5b83\u5fc5\u987b\u6307\u5b9a\u4e3a\u201cPRIMARY KEY\u201d\u3002\u5982\u679c\u4f60\u66fe\u7ecf\u7528\u8fc7AUTO_INCREMENT\u7c7b\u578b\u7684\u5217\uff0c\u4f60\u53ef\u80fd\u5df2\u7ecf\u719f\u6089\u4e3b\u952e\u4e4b\u7c7b\u7684\u6982\u5ff5\u4e86\u3002\u4e3b\u952e\u4e00\u822c\u5728\u521b\u5efa\u8868\u7684\u65f6\u5019\u6307\u5b9a\uff0c\u4f8b\u5982\u201cCREATE TABLE tablename ( [&#8230;], PRIMARY KEY (\u5217\u7684\u5217\u8868) ); \u201d\u3002\u4f46\u662f\uff0c\u6211\u4eec\u4e5f\u53ef\u4ee5\u901a\u8fc7\u4fee\u6539\u8868\u7684\u65b9\u5f0f\u52a0\u5165\u4e3b\u952e\uff0c\u4f8b\u5982\u201cALTER TABLE tablename ADD PRIMARY KEY (\u5217\u7684\u5217\u8868); \u201d\u3002\u6bcf\u4e2a\u8868\u53ea\u80fd\u6709\u4e00\u4e2a\u4e3b\u952e\u3002<\/p>\n<p>\u5168\u6587\u7d22\u5f15\nMySQL\u4ece3.23.23\u7248\u5f00\u59cb\u652f\u6301\u5168\u6587\u7d22\u5f15\u548c\u5168\u6587\u68c0\u7d22\u3002\u5728MySQL\u4e2d\uff0c\u5168\u6587\u7d22\u5f15\u7684\u7d22\u5f15\u7c7b\u578b\u4e3aFULLTEXT\u3002\u5168\u6587\u7d22\u5f15\u53ef\u4ee5\u5728VARCHAR\u6216\u8005TEXT\u7c7b\u578b\u7684\u5217\u4e0a\u521b\u5efa\u3002\u5b83\u53ef\u4ee5\u901a\u8fc7CREATE TABLE\u547d\u4ee4\u521b\u5efa\uff0c\u4e5f\u53ef\u4ee5\u901a\u8fc7ALTER TABLE\u6216CREATE INDEX\u547d\u4ee4\u521b\u5efa\u3002\u5bf9\u4e8e\u5927\u89c4\u6a21\u7684\u6570\u636e\u96c6\uff0c\u901a\u8fc7ALTER TABLE\uff08\u6216\u8005CREATE INDEX\uff09\u547d\u4ee4\u521b\u5efa\u5168\u6587\u7d22\u5f15\u8981\u6bd4\u628a\u8bb0\u5f55\u63d2\u5165\u5e26\u6709\u5168\u6587\u7d22\u5f15\u7684\u7a7a\u8868\u66f4\u5feb\u3002\u672c\u6587\u4e0b\u9762\u7684\u8ba8\u8bba\u4e0d\u518d\u6d89\u53ca\u5168\u6587\u7d22\u5f15\uff0c\u8981\u4e86\u89e3\u66f4\u591a\u4fe1\u606f\uff0c\u8bf7\u53c2\u89c1MySQL documentation\u3002<\/p>\n<p>\u4e09\u3001\u5355\u5217\u7d22\u5f15\u4e0e\u591a\u5217\u7d22\u5f15\n\u7d22\u5f15\u53ef\u4ee5\u662f\u5355\u5217\u7d22\u5f15\uff0c\u4e5f\u53ef\u4ee5\u662f\u591a\u5217\u7d22\u5f15\u3002\u4e0b\u9762\u6211\u4eec\u901a\u8fc7\u5177\u4f53\u7684\u4f8b\u5b50\u6765\u8bf4\u660e\u8fd9\u4e24\u79cd\u7d22\u5f15\u7684\u533a\u522b\u3002\u5047\u8bbe\u6709\u8fd9\u6837\u4e00\u4e2apeople\u8868\uff1a<\/p>\n<p>CREATE TABLE people ( peopleid SMALLINT NOT NULL AUTO_INCREMENT, firstname CHAR(50) NOT NULL, lastname CHAR(50) NOT NULL, age SMALLINT NOT NULL, townid SMALLINT NOT NULL, PRIMARY KEY (peopleid) );<\/p>\n<p>\u4e0b\u9762\u662f\u6211\u4eec\u63d2\u5165\u5230\u8fd9\u4e2apeople\u8868\u7684\u6570\u636e\uff1a<\/p>\n<p>\u8fd9\u4e2a\u6570\u636e\u7247\u6bb5\u4e2d\u6709\u56db\u4e2a\u540d\u5b57\u4e3a\u201cMikes\u201d\u7684\u4eba\uff08\u5176\u4e2d\u4e24\u4e2a\u59d3Sullivans\uff0c\u4e24\u4e2a\u59d3McConnells\uff09\uff0c\u6709\u4e24\u4e2a\u5e74\u9f84\u4e3a17\u5c81\u7684\u4eba\uff0c\u8fd8\u6709\u4e00\u4e2a\u540d\u5b57\u4e0e\u4f17\u4e0d\u540c\u7684Joe Smith\u3002<\/p>\n<p>\u8fd9\u4e2a\u8868\u7684\u4e3b\u8981\u7528\u9014\u662f\u6839\u636e\u6307\u5b9a\u7684\u7528\u6237\u59d3\u3001\u540d\u4ee5\u53ca\u5e74\u9f84\u8fd4\u56de\u76f8\u5e94\u7684peopleid\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u53ef\u80fd\u9700\u8981\u67e5\u627e\u59d3\u540d\u4e3aMike Sullivan\u3001\u5e74\u9f8417\u5c81\u7528\u6237\u7684peopleid\uff08SQL\u547d\u4ee4\u4e3aSELECT peopleid FROM people WHERE firstname=&#8217;Mike&#8217; AND lastname=&#8217;Sullivan&#8217; AND age=17;\uff09\u3002\u7531\u4e8e\u6211\u4eec\u4e0d\u60f3\u8ba9MySQL\u6bcf\u6b21\u6267\u884c\u67e5\u8be2\u5c31\u53bb\u626b\u63cf\u6574\u4e2a\u8868\uff0c\u8fd9\u91cc\u9700\u8981\u8003\u8651\u8fd0\u7528\u7d22\u5f15\u3002<\/p>\n<p>\u9996\u5148\uff0c\u6211\u4eec\u53ef\u4ee5\u8003\u8651\u5728\u5355\u4e2a\u5217\u4e0a\u521b\u5efa\u7d22\u5f15\uff0c\u6bd4\u5982firstname\u3001lastname\u6216\u8005age\u5217\u3002\u5982\u679c\u6211\u4eec\u521b\u5efafirstname\u5217\u7684\u7d22\u5f15\uff08ALTER TABLE people ADD INDEX firstname (firstname);\uff09\uff0cMySQL\u5c06\u901a\u8fc7\u8fd9\u4e2a\u7d22\u5f15\u8fc5\u901f\u628a\u641c\u7d22\u8303\u56f4\u9650\u5236\u5230\u90a3\u4e9bfirstname=&#8217;Mike&#8217;\u7684\u8bb0\u5f55\uff0c\u7136\u540e\u518d\u5728\u8fd9\u4e2a\u201c\u4e2d\u95f4\u7ed3\u679c\u96c6\u201d\u4e0a\u8fdb\u884c\u5176\u4ed6\u6761\u4ef6\u7684\u641c\u7d22\uff1a\u5b83\u9996\u5148\u6392\u9664\u90a3\u4e9blastname\u4e0d\u7b49\u4e8e\u201cSullivan\u201d\u7684\u8bb0\u5f55\uff0c\u7136\u540e\u6392\u9664\u90a3\u4e9bage\u4e0d\u7b49\u4e8e17\u7684\u8bb0\u5f55\u3002\u5f53\u8bb0\u5f55\u6ee1\u8db3\u6240\u6709\u641c\u7d22\u6761\u4ef6\u4e4b\u540e\uff0cMySQL\u5c31\u8fd4\u56de\u6700\u7ec8\u7684\u641c\u7d22\u7ed3\u679c\u3002<\/p>\n<p>\u7531\u4e8e\u5efa\u7acb\u4e86firstname\u5217\u7684\u7d22\u5f15\uff0c\u4e0e\u6267\u884c\u8868\u7684\u5b8c\u5168\u626b\u63cf\u76f8\u6bd4\uff0cMySQL\u7684\u6548\u7387\u63d0\u9ad8\u4e86\u5f88\u591a\uff0c\u4f46\u6211\u4eec\u8981\u6c42MySQL\u626b\u63cf\u7684\u8bb0\u5f55\u6570\u91cf\u4ecd\u65e7\u8fdc\u8fdc\u8d85\u8fc7\u4e86\u5b9e\u9645\u6240\u9700\u8981\u7684\u3002\u867d\u7136\u6211\u4eec\u53ef\u4ee5\u5220\u9664firstname\u5217\u4e0a\u7684\u7d22\u5f15\uff0c\u518d\u521b\u5efalastname\u6216\u8005 age\u5217\u7684\u7d22\u5f15\uff0c\u4f46\u603b\u5730\u770b\u6765\uff0c\u4e0d\u8bba\u5728\u54ea\u4e2a\u5217\u4e0a\u521b\u5efa\u7d22\u5f15\u641c\u7d22\u6548\u7387\u4ecd\u65e7\u76f8\u4f3c\u3002<\/p>\n<p>\u4e3a\u4e86\u63d0\u9ad8\u641c\u7d22\u6548\u7387\uff0c\u6211\u4eec\u9700\u8981\u8003\u8651\u8fd0\u7528\u591a\u5217\u7d22\u5f15\u3002\u5982\u679c\u4e3afirstname\u3001lastname\u548cage\u8fd9\u4e09\u4e2a\u5217\u521b\u5efa\u4e00\u4e2a\u591a\u5217\u7d22\u5f15\uff0cMySQL\u53ea\u9700\u4e00\u6b21\u68c0\u7d22\u5c31\u80fd\u591f\u627e\u51fa\u6b63\u786e\u7684\u7ed3\u679c\uff01\u4e0b\u9762\u662f\u521b\u5efa\u8fd9\u4e2a\u591a\u5217\u7d22\u5f15\u7684SQL\u547d\u4ee4\uff1a<\/p>\n<p>ALTER TABLE people ADD INDEX fname_lname_age (firstname,lastname,age);<\/p>\n<p>\u7531\u4e8e\u7d22\u5f15\u6587\u4ef6\u4ee5B-\u6811\u683c\u5f0f\u4fdd\u5b58\uff0cMySQL\u80fd\u591f\u7acb\u5373\u8f6c\u5230\u5408\u9002\u7684firstname\uff0c\u7136\u540e\u518d\u8f6c\u5230\u5408\u9002\u7684lastname\uff0c\u6700\u540e\u8f6c\u5230\u5408\u9002\u7684age\u3002\u5728\u6ca1\u6709\u626b\u63cf\u6570\u636e\u6587\u4ef6\u4efb\u4f55\u4e00\u4e2a\u8bb0\u5f55\u7684\u60c5\u51b5\u4e0b\uff0cMySQL\u5c31\u6b63\u786e\u5730\u627e\u51fa\u4e86\u641c\u7d22\u7684\u76ee\u6807\u8bb0\u5f55\uff01<\/p>\n<p>\u90a3\u4e48\uff0c\u5982\u679c\u5728firstname\u3001lastname\u3001age\u8fd9\u4e09\u4e2a\u5217\u4e0a\u5206\u522b\u521b\u5efa\u5355\u5217\u7d22\u5f15\uff0c\u6548\u679c\u662f\u5426\u548c\u521b\u5efa\u4e00\u4e2afirstname\u3001lastname\u3001 age\u7684\u591a\u5217\u7d22\u5f15\u4e00\u6837\u5462\uff1f\u7b54\u6848\u662f\u5426\u5b9a\u7684\uff0c\u4e24\u8005\u5b8c\u5168\u4e0d\u540c\u3002\u5f53\u6211\u4eec\u6267\u884c\u67e5\u8be2\u7684\u65f6\u5019\uff0cMySQL\u53ea\u80fd\u4f7f\u7528\u4e00\u4e2a\u7d22\u5f15\u3002\u5982\u679c\u4f60\u6709\u4e09\u4e2a\u5355\u5217\u7684\u7d22\u5f15\uff0cMySQL\u4f1a\u8bd5\u56fe\u9009\u62e9\u4e00\u4e2a\u9650\u5236\u6700\u4e25\u683c\u7684\u7d22\u5f15\u3002\u4f46\u662f\uff0c\u5373\u4f7f\u662f\u9650\u5236\u6700\u4e25\u683c\u7684\u5355\u5217\u7d22\u5f15\uff0c\u5b83\u7684\u9650\u5236\u80fd\u529b\u4e5f\u80af\u5b9a\u8fdc\u8fdc\u4f4e\u4e8efirstname\u3001lastname\u3001age\u8fd9\u4e09\u4e2a\u5217\u4e0a\u7684\u591a\u5217\u7d22\u5f15\u3002<\/p>\n<p>\u56db\u3001\u6700\u5de6\u524d\u7f00\n\u591a\u5217\u7d22\u5f15\u8fd8\u6709\u53e6\u5916\u4e00\u4e2a\u4f18\u70b9\uff0c\u5b83\u901a\u8fc7\u79f0\u4e3a\u6700\u5de6\u524d\u7f00\uff08Leftmost Prefixing\uff09\u7684\u6982\u5ff5\u4f53\u73b0\u51fa\u6765\u3002\u7ee7\u7eed\u8003\u8651\u524d\u9762\u7684\u4f8b\u5b50\uff0c\u73b0\u5728\u6211\u4eec\u6709\u4e00\u4e2afirstname\u3001lastname\u3001age\u5217\u4e0a\u7684\u591a\u5217\u7d22\u5f15\uff0c\u6211\u4eec\u79f0\u8fd9\u4e2a\u7d22\u5f15\u4e3afname_lname_age\u3002\u5f53\u641c\u7d22\u6761\u4ef6\u662f\u4ee5\u4e0b\u5404\u79cd\u5217\u7684\u7ec4\u5408\u65f6\uff0cMySQL\u5c06\u4f7f\u7528fname_lname_age\u7d22\u5f15\uff1a<\/p>\n<p>firstname\uff0clastname\uff0cage\nfirstname\uff0clastname\nfirstname\n\u4ece\u53e6\u4e00\u65b9\u9762\u7406\u89e3\uff0c\u5b83\u76f8\u5f53\u4e8e\u6211\u4eec\u521b\u5efa\u4e86(firstname\uff0clastname\uff0cage)\u3001(firstname\uff0clastname)\u4ee5\u53ca(firstname)\u8fd9\u4e9b\u5217\u7ec4\u5408\u4e0a\u7684\u7d22\u5f15\u3002\u4e0b\u9762\u8fd9\u4e9b\u67e5\u8be2\u90fd\u80fd\u591f\u4f7f\u7528\u8fd9\u4e2afname_lname_age\u7d22\u5f15\uff1a<\/p>\n<p>SELECT peopleid FROM people WHERE firstname=&#8217;Mike&#8217; AND lastname=&#8217;Sullivan&#8217; AND age=&#8217;17&#8217;; SELECT peopleid FROM people WHERE firstname=&#8217;Mike&#8217; AND lastname=&#8217;Sullivan&#8217;; SELECT peopleid FROM people WHERE firstname=&#8217;Mike&#8217;; The following queries cannot use the index at all: SELECT peopleid FROM people WHERE lastname=&#8217;Sullivan&#8217;; SELECT peopleid FROM people WHERE age=&#8217;17&#8217;; SELECT peopleid FROM people WHERE lastname=&#8217;Sullivan&#8217; AND age=&#8217;17&#8217;;<\/p>\n<p>\u4e94\u3001\u9009\u62e9\u7d22\u5f15\u5217\n\u5728\u6027\u80fd\u4f18\u5316\u8fc7\u7a0b\u4e2d\uff0c\u9009\u62e9\u5728\u54ea\u4e9b\u5217\u4e0a\u521b\u5efa\u7d22\u5f15\u662f\u6700\u91cd\u8981\u7684\u6b65\u9aa4\u4e4b\u4e00\u3002\u53ef\u4ee5\u8003\u8651\u4f7f\u7528\u7d22\u5f15\u7684\u4e3b\u8981\u6709\u4e24\u79cd\u7c7b\u578b\u7684\u5217\uff1a\u5728WHERE\u5b50\u53e5\u4e2d\u51fa\u73b0\u7684\u5217\uff0c\u5728join\u5b50\u53e5\u4e2d\u51fa\u73b0\u7684\u5217\u3002\u8bf7\u770b\u4e0b\u9762\u8fd9\u4e2a\u67e5\u8be2\uff1a<\/p>\n<p>SELECT age ## \u4e0d\u4f7f\u7528\u7d22\u5f15\nFROM people WHERE firstname=&#8217;Mike&#8217; ## \u8003\u8651\u4f7f\u7528\u7d22\u5f15\nAND lastname=&#8217;Sullivan&#8217; ## \u8003\u8651\u4f7f\u7528\u7d22\u5f15<\/p>\n<p>\u8fd9\u4e2a\u67e5\u8be2\u4e0e\u524d\u9762\u7684\u67e5\u8be2\u7565\u6709\u4e0d\u540c\uff0c\u4f46\u4ecd\u5c5e\u4e8e\u7b80\u5355\u67e5\u8be2\u3002\u7531\u4e8eage\u662f\u5728SELECT\u90e8\u5206\u88ab\u5f15\u7528\uff0cMySQL\u4e0d\u4f1a\u7528\u5b83\u6765\u9650\u5236\u5217\u9009\u62e9\u64cd\u4f5c\u3002\u56e0\u6b64\uff0c\u5bf9\u4e8e\u8fd9\u4e2a\u67e5\u8be2\u6765\u8bf4\uff0c\u521b\u5efaage\u5217\u7684\u7d22\u5f15\u6ca1\u6709\u4ec0\u4e48\u5fc5\u8981\u3002\u4e0b\u9762\u662f\u4e00\u4e2a\u66f4\u590d\u6742\u7684\u4f8b\u5b50\uff1a<\/p>\n<p>SELECT people.age, ##\u4e0d\u4f7f\u7528\u7d22\u5f15\ntown.name ##\u4e0d\u4f7f\u7528\u7d22\u5f15\nFROM people LEFT JOIN town ON\npeople.townid=town.townid ##\u8003\u8651\u4f7f\u7528\u7d22\u5f15\nWHERE firstname=&#8217;Mike&#8217; ##\u8003\u8651\u4f7f\u7528\u7d22\u5f15\nAND lastname=&#8217;Sullivan&#8217; ##\u8003\u8651\u4f7f\u7528\u7d22\u5f15<\/p>\n<p>\u4e0e\u524d\u9762\u7684\u4f8b\u5b50\u4e00\u6837\uff0c\u7531\u4e8efirstname\u548clastname\u51fa\u73b0\u5728WHERE\u5b50\u53e5\u4e2d\uff0c\u56e0\u6b64\u8fd9\u4e24\u4e2a\u5217\u4ecd\u65e7\u6709\u521b\u5efa\u7d22\u5f15\u7684\u5fc5\u8981\u3002\u9664\u6b64\u4e4b\u5916\uff0c\u7531\u4e8etown\u8868\u7684townid\u5217\u51fa\u73b0\u5728join\u5b50\u53e5\u4e2d\uff0c\u56e0\u6b64\u6211\u4eec\u9700\u8981\u8003\u8651\u521b\u5efa\u8be5\u5217\u7684\u7d22\u5f15\u3002<\/p>\n<p>\u90a3\u4e48\uff0c\u6211\u4eec\u662f\u5426\u53ef\u4ee5\u7b80\u5355\u5730\u8ba4\u4e3a\u5e94\u8be5\u7d22\u5f15WHERE\u5b50\u53e5\u548cjoin\u5b50\u53e5\u4e2d\u51fa\u73b0\u7684\u6bcf\u4e00\u4e2a\u5217\u5462\uff1f\u5dee\u4e0d\u591a\u5982\u6b64\uff0c\u4f46\u5e76\u4e0d\u5b8c\u5168\u3002\u6211\u4eec\u8fd8\u5fc5\u987b\u8003\u8651\u5230\u5bf9\u5217\u8fdb\u884c\u6bd4\u8f83\u7684\u64cd\u4f5c\u7b26\u7c7b\u578b\u3002MySQL\u53ea\u6709\u5bf9\u4ee5\u4e0b\u64cd\u4f5c\u7b26\u624d\u4f7f\u7528\u7d22\u5f15\uff1a<\uff0c<=\uff0c=\uff0c>\uff0c>=\uff0cBETWEEN\uff0cIN\uff0c\u4ee5\u53ca\u67d0\u4e9b\u65f6\u5019\u7684LIKE\u3002\u53ef\u4ee5\u5728LIKE\u64cd\u4f5c\u4e2d\u4f7f\u7528\u7d22\u5f15\u7684\u60c5\u5f62\u662f\u6307\u53e6\u4e00\u4e2a\u64cd\u4f5c\u6570\u4e0d\u662f\u4ee5\u901a\u914d\u7b26\uff08%\u6216\u8005_\uff09\u5f00\u5934\u7684\u60c5\u5f62\u3002\u4f8b\u5982\uff0c\u201cSELECT peopleid FROM peopleWHERE firstname LIKE &#8216;Mich%&#8217;;\u201d\u8fd9\u4e2a\u67e5\u8be2\u5c06\u4f7f\u7528\u7d22\u5f15\uff0c\u4f46\u201cSELECT peopleid FROM people WHERE firstname LIKE &#8216;%ike&#8217;;\u201d\u8fd9\u4e2a\u67e5\u8be2\u4e0d\u4f1a\u4f7f\u7528\u7d22\u5f15\u3002<\/p>\n<p>\u516d\u3001\u5206\u6790\u7d22\u5f15\u6548\u7387<\/p>\n<p>\u73b0\u5728\u6211\u4eec\u5df2\u7ecf\u77e5\u9053\u4e86\u4e00\u4e9b\u5982\u4f55\u9009\u62e9\u7d22\u5f15\u5217\u7684\u77e5\u8bc6\uff0c\u4f46\u8fd8\u65e0\u6cd5\u5224\u65ad\u54ea\u4e00\u4e2a\u6700\u6709\u6548\u3002MySQL\u63d0\u4f9b\u4e86\u4e00\u4e2a\u5185\u5efa\u7684SQL\u547d\u4ee4\u5e2e\u52a9<\/p>\n<p>\u4e00\u3001 MySQL\u5efa\u8868\uff0c\u5b57\u6bb5\u9700\u8bbe\u7f6e\u4e3a\u975e\u7a7a\uff0c\u9700\u8bbe\u7f6e\u5b57\u6bb5\u9ed8\u8ba4\u503c\u3002<\/p>\n<p>\u4e8c\u3001 MySQL\u5efa\u8868\uff0c\u5b57\u6bb5\u9700NULL\u65f6\uff0c\u9700\u8bbe\u7f6e\u5b57\u6bb5\u9ed8\u8ba4\u503c\uff0c\u9ed8\u8ba4\u503c\u4e0d\u4e3aNULL\u3002<\/p>\n<p>\u4e09\u3001 MySQL\u5efa\u8868\uff0c\u5982\u679c\u5b57\u6bb5\u7b49\u4ef7\u4e8e\u5916\u952e\uff0c\u5e94\u5728\u8be5\u5b57\u6bb5\u52a0\u7d22\u5f15\u3002<\/p>\n<p>\u56db\u3001 MySQL\u5efa\u8868\uff0c\u4e0d\u540c\u8868\u4e4b\u95f4\u7684\u76f8\u540c\u5c5e\u6027\u503c\u7684\u5b57\u6bb5\uff0c\u5217\u7c7b\u578b\uff0c\u7c7b\u578b\u957f\u5ea6\uff0c\u662f\u5426\u975e\u7a7a\uff0c\u662f\u5426\u9ed8\u8ba4\u503c\uff0c\u9700\u4fdd\u6301\u4e00\u81f4\uff0c\u5426\u5219\u65e0\u6cd5\u6b63\u786e\u4f7f\u7528\u7d22\u5f15\u8fdb\u884c\u5173\u8054\u5bf9\u6bd4\u3002<\/p>\n<p>\u4e94\u3001 MySQL\u4f7f\u7528\u65f6\uff0c\u4e00\u6761SQL\u8bed\u53e5\u53ea\u80fd\u4f7f\u7528\u4e00\u4e2a\u8868\u7684\u4e00\u4e2a\u7d22\u5f15\u3002\u6240\u6709\u7684\u5b57\u6bb5\u7c7b\u578b\u90fd\u53ef\u4ee5\u7d22\u5f15\uff0c\u591a\u5217\u7d22\u5f15\u7684\u5c5e\u6027\u6700\u591a15\u4e2a\u3002<\/p>\n<p>\u516d\u3001 \u5982\u679c\u53ef\u4ee5\u5728\u591a\u4e2a\u7d22\u5f15\u4e2d\u8fdb\u884c\u9009\u62e9\uff0cMySQL\u901a\u5e38\u4f7f\u7528\u627e\u5230\u6700\u5c11\u884c\u7684\u7d22\u5f15\uff0c\u7d22\u5f15\u552f\u4e00\u503c\u6700\u9ad8\u7684\u7d22\u5f15\u3002<\/p>\n<p>\u4e03\u3001 \u5efa\u7acb\u7d22\u5f15index\uff08part1,part2,part3\uff09,\u76f8\u5f53\u4e8e\u5efa\u7acb\u4e86 index(part1),index(part1,part2)\u548cindex\uff08part1,part2,part3\uff09\u4e09\u4e2a\u7d22\u5f15\u3002<\/p>\n<p>\u516b\u3001 MySQL\u9488\u5bf9like\u8bed\u6cd5\u5fc5\u987b\u5982\u4e0b\u683c\u5f0f\u624d\u4f7f\u7528\u7d22\u5f15\uff1a<\/p>\n<p>SELECT * FROM t1 WHERE key_col LIKE &#8216;ab%&#8217; \uff1b<\/p>\n<p>\u4e5d\u3001 SELECT COUNT(*) \u8bed\u6cd5\u5728\u6ca1\u6709where\u6761\u4ef6\u7684\u8bed\u53e5\u4e2d\u6267\u884c\u6548\u7387\u6ca1\u6709SELECT COUNT(col_name)\u5feb\uff0c\u4f46\u662f\u5728\u6709where\u6761\u4ef6\u7684\u8bed\u53e5\u4e2d\u6267\u884c\u6548\u7387\u8981\u5feb\u3002<\/p>\n<p>\u5341\u3001 \u5728where\u6761\u4ef6\u4e2d\u591a\u4e2aand\u7684\u6761\u4ef6\u4e2d\uff0c\u5fc5\u987b\u90fd\u662f\u4e00\u4e2a\u591a\u5217\u7d22\u5f15\u7684key_part\u5c5e\u6027\u800c\u4e14\u5fc5\u987b\u5305\u542bkey_part1\u3002\u5404\u81ea\u5355\u4e00\u7d22\u5f15\u7684\u8bdd\uff0c\u53ea\u4f7f\u7528\u904d\u5386\u6700\u5c11\u884c\u7684\u90a3\u4e2a\u7d22\u5f15\u3002<\/p>\n<p>\u5341\u4e00\u3001 \u5728where\u6761\u4ef6\u4e2d\u591a\u4e2aor\u7684\u6761\u4ef6\u4e2d\uff0c\u6bcf\u4e00\u4e2a\u6761\u4ef6\uff0c\u90fd\u5fc5\u987b\u662f\u4e00\u4e2a\u6709\u6548\u7d22\u5f15\u3002<\/p>\n<p>\u5341\u4e8c\u3001 ORDER BY \u540e\u9762\u7684\u6761\u4ef6\u5fc5\u987b\u662f\u540c\u4e00\u7d22\u5f15\u7684\u5c5e\u6027\uff0c\u6392\u5e8f\u987a\u5e8f\u5fc5\u987b\u4e00\u81f4\uff08\u6bd4\u5982\u90fd\u662f\u5347\u5e8f\u6216\u90fd\u662f\u964d\u5e8f\uff09\u3002<\/p>\n<p>\u5341\u4e09\u3001 \u6240\u6709GROUP BY\u5217\u5f15\u7528\u540c\u4e00\u7d22\u5f15\u7684\u5c5e\u6027\uff0c\u5e76\u4e14\u7d22\u5f15\u5fc5\u987b\u662f\u6309\u987a\u5e8f\u4fdd\u5b58\u5176\u5173\u952e\u5b57\u7684\u3002<\/p>\n<p>\u5341\u56db\u3001 JOIN \u7d22\u5f15\uff0c\u6240\u6709\u5339\u914dON\u548cwhere\u7684\u5b57\u6bb5\u5e94\u5efa\u7acb\u5408\u9002\u7684\u7d22\u5f15\u3002<\/p>\n<p>\u5341\u4e94\u3001 \u5bf9\u667a\u80fd\u7684\u626b\u63cf\u5168\u8868\u4f7f\u7528FORCE INDEX\u544a\u77e5MySQL\uff0c\u4f7f\u7528\u7d22\u5f15\u6548\u7387\u66f4\u9ad8\u3002<\/p>\n<p>\u5341\u516d\u3001 \u5b9a\u671fANALYZE TABLE tbl_name\u4e3a\u626b\u63cf\u7684\u8868\u66f4\u65b0\u5173\u952e\u5b57\u5206\u5e03 \u3002<\/p>\n<p>\u5341\u4e03\u3001 \u5b9a\u671f\u4f7f\u7528\u6162\u65e5\u5fd7\u68c0\u67e5\u8bed\u53e5\uff0c\u6267\u884cexplain\uff0c\u5206\u6790\u53ef\u80fd\u6539\u8fdb\u7684\u7d22\u5f15\u3002<\/p>\n<p>\u5341\u516b\u3001 \u6761\u4ef6\u5141\u8bb8\u7684\u8bdd\uff0c\u8bbe\u7f6e\u8f83\u5927\u7684key_buffer_size\u548cquery_cache_size\u7684\u503c\uff08\u5168\u5c40\u53c2\u6570\uff09\uff0c\u548csort_buffer_size\u7684\u503c\uff08session\u53d8\u91cf\uff0c\u5efa\u8bae\u4e0d\u8981\u8d85\u8fc74M\uff09\u3002<\/p>","protected":false},"excerpt":{"rendered":"<p>FROM:<a href=\"http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482\">http:\/\/blog.csdn.net\/tianmo2010\/article\/details\/7930482<\/a> \u2460MySQL Index \u4e00\u3001SHOW INDEX\u4f1a\u8fd4\u56de\u4ee5\u4e0b\u5b57\u6bb5 1\u3001Tabl&#46;&#46;&#46;<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,101],"tags":[420,100,443],"class_list":["post-1468","post","type-post","status-publish","format-standard","hentry","category-linux","category-db","tag-index","tag-mysql","tag-db"],"_links":{"self":[{"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/posts\/1468","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/comments?post=1468"}],"version-history":[{"count":1,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/posts\/1468\/revisions"}],"predecessor-version":[{"id":1469,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/posts\/1468\/revisions\/1469"}],"wp:attachment":[{"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/media?parent=1468"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/categories?post=1468"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/tags?post=1468"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}