{"id":872,"date":"2017-08-21T00:02:28","date_gmt":"2017-08-20T16:02:28","guid":{"rendered":"http:\/\/www.5x44.cn\/?p=872"},"modified":"2017-08-31T21:23:25","modified_gmt":"2017-08-31T13:23:25","slug":"mysql%e7%b4%a2%e5%bc%95%e6%9f%a5%e8%af%a2%e4%bc%98%e5%8c%96","status":"publish","type":"post","link":"https:\/\/www.5x44.cn\/?p=872","title":{"rendered":"mysql\u7d22\u5f15\u67e5\u8be2\u4f18\u5316"},"content":{"rendered":"<p>\u4e00\u3001\u6bcf\u4e2a\u7d22\u5f15\u503c\u5bf9\u5e94\u4e00\u4e2a\u4e3b\u952eID\uff0c\u56e0\u4e3aInnoDB\u6839\u636e\u4e3b\u952eID\u6392\u5e8f\u5b58\u50a8\u6570\u636e\u3002<\/p>\n<p>\u4e8c\u3001\u7d22\u5f15\u540c\u6837\u5360\u7528\u7a7a\u95f4\uff0c\u5b58\u5728IBD\u6587\u4ef6\u4e2d\u3002\uff08\u4e5f\u8bb8\u5427\uff01\u8fd8\u6ca1\u5f97\u5230\u786e\u8ba4\uff09<\/p>\n<p>\u4e09\u3001MyIsam\u8868\u548cORACLE\u90fd\u662f\u5806\u8868\u7ed3\u6784\u3002<\/p>\n<p>\u56db\u3001\u7d22\u5f15\u4f7f\u7528<strong>\u4e8c\u5206\u67e5\u627e\u6cd5<\/strong>\uff0cB+tree\u7ed3\u6784\u3002<\/p>\n<ul>\n<li>B+TREE\u7684\u7237\u8282\u70b9\u5b58\u653e\u5b50\u8282\u70b9\u7684\u5b58\u50a8\u8303\u56f4\uff0c\u6570\u636e\u90fd\u5b58\u5728\u53f6\u5b50\u70b9\u4e2d\u3002\u5982\u679c\u53f6\u5b50\u8282\u70b9\u4e0a\u6709\u591a\u6761\u91cd\u590d\u6570\u636e\uff0c\u91cd\u590d\u6570\u636e\u7528\u5168\u8868\u626b\u63cf\u7684\u65b9\u5f0f\u3002\uff08\u5e94\u8be5 \u5c31\u662f\u8fd9\u6837\uff09<\/li>\n<\/ul>\n<p>\u4e94\u3001InnoDB\u8868\u805a\u7c07\u7d22\u5f15<\/p>\n<ul>\n<li>\u7d22\u5f15\u4e2d\u5305\u542b\u7d22\u5f15\u9879\u548c\u4e3b\u952eID<\/li>\n<li>\u7d22\u5f15\u503c\u5982\u679c\u76f8\u540c\uff0c\u90a3\u4e48\u6839\u636e\u4e3b\u952eID\u6392\u5e8f\u3002<\/li>\n<\/ul>\n<p>\u516d\u3001\u5efa\u7acb\u7d22\u5f15\u7684\u547d\u4ee4\uff1a<\/p>\n<ul>\n<li><code>create index idx_name on table_name(column_name[(len)])<\/code><br \/>\nlen\u662f\u53ef\u9009\u53c2\u6570\uff0c\u56e0\u4e3a\u5728\u957f\u5b57\u6bb5\u4e0a\u5efa\u7acb\u7d22\u5f15\u975e\u5e38\u5f71\u54cd\u6027\u80fd\uff0c\u6240\u4ee5\u53ef\u4ee5\u901a\u8fc7len\u6307\u5b9a\u5b57\u6bb5\u957f\u5ea6\u3002innoDB\u53ea\u80fd\u53d6\u524d<strong>767bytes<\/strong>\u505a\u4e3a\u7d22\u5f15\uff0c\u9664\u975e\u8bbe\u7f6e\u4e86<a class=\"link\" href=\"https:\/\/dev.mysql.com\/doc\/refman\/5.7\/en\/innodb-parameters.html#sysvar_innodb_large_prefix\"><code class=\"literal\">innodb_large_prefix<\/code><\/a> \u53d8\u91cf\u3002<\/li>\n<li>\u6240\u6709\u7684\u5b58\u50a8\u5f15\u64ce\u90fd\u652f\u6301\u6bcf\u4e2a\u8868\u81f3\u5c1116\u4e2a\u7d22\u5f15\u5e76\u4e14\u603b\u7684\u7d22\u5f15\u957f\u5ea6\u81f3\u5c11256\u5b57\u8282\u3002\uff08All storage engines support at least 16 indexes per table and a total index length of at least 256 bytes.\uff09<\/li>\n<li>\u590d\u5408\u7d22\u5f15\u6700\u591a\u753116\u4e2a\u5217\u7ec4\u6210\u3002\uff08An index may consist of up to 16 columns\uff09<\/li>\n<li>\u5217\u53ef\u4ee5\u662fNULL\uff0c\u9664\u975e\u7d22\u5f15\u662f\u4e3b\u952e\u3002\uff08Columns can be <code class=\"literal\">NULL<\/code> unless the index is a primary key\uff09<\/li>\n<li>\u5bf9\u957f\u5b57\u6bb5\u7684\u7d22\u5f15\u5904\u7406\u65b9\u6cd5\u662f\u622a\u53d6\u524d\u9762\u4e00\u90e8\u5206\u4f5c\u4e3a\u7d22\u5f15\u9879\uff0c\u5982\uff0cemail\u5b57\u6bb5\uff0c\u901a\u5e38@\u7684\u540e\u9762\u53d8\u5316\u4e0d\u5927\uff0c\u6240\u4ee5\u53ea\u8981\u622a\u53d6\u524d\u976230\u4e2a\u5b57\u7b26\u8db3\u591f\u5904\u7406\u4e86\u3002<\/li>\n<li>\u5982\u679c\u957f\u5b57\u6bb5\u524d\u9762\u7684\u53d8\u5316\u5f88\u5c0f\uff0c\u540e\u9762\u7684\u53d8\u5316\u6bd4\u8f83\u591a\uff0c\u5982\uff0c\u4f4f\u5740\u4fe1\u606f\uff0c\u8fd9\u79cd\u53ef\u4ee5\u91c7\u53d6\u5206\u5b57\u6bb5\u5b58\u50a8\u7684\u65b9\u5f0f\uff0c\u4e5f\u5c31\u662f\u7701\u3001\u5e02\u3001\u8857\u9053\u5206\u6210\u4e09\u4e2a\u5b57\u6bb5\u5b58\u50a8\u3002<\/li>\n<\/ul>\n<p>\u4e03\u3001\u7d22\u5f15\u7ef4\u62a4<\/p>\n<ul>\n<li>\u7531\u4e8e\u6570\u636e\u5e93\u5185\u5bb9\u53d8\u66f4\u5bfc\u81f3\u7d22\u5f15\u503c\u91cd\u65b0\u6392\u5e8f\u7684\u60c5\u51b5\uff0c\u53eb\u505a\u7d22\u5f15\u7ef4\u62a4\uff0c\u7d22\u5f15\u7ef4\u62a4\u662f\u7531\u6570\u636e\u5e93\u81ea\u52a8\u5b8c\u6210\u7684\uff0c\uff08\u4ec0\u4e48\u65f6\u5019\u8fdb\u884c\uff1f\uff09<\/li>\n<li>\u7531\u4e8e\u7d22\u76f8\u7ef4\u62a4\u662f\u5728\u7528\u6237\u4e0d\u53ef\u611f\u77e5\u7684\u60c5\u51b5\u4e0b\u81ea\u52a8\u5b8c\u6210\u7684\uff0c\u6570\u636e\u5e93\u5bf9\u5f71\u54cd\u7d22\u5f15\u7684insert,update,delete\u7684\u64cd\u4f5c\uff0c\u5185\u90e8\u4f1a\u5c01\u88c5\u6210\u4e00\u4e2a\u4e8b\u52a1\uff0c\u66f4\u65b0\u7d22\u5f15\u8868\uff08\u6bcf\u4e2a\u7d22\u5f15\u662f\u4e00\u4e2a\u5355\u72ec\u7684\u8868\uff0c\u5185\u90e8\u6570\u636e\u662f\u7d22\u5f15\u9879\u548c\u4e3b\u952eID\u6784\u6210\uff09\uff0c\u6240\u4ee5\u5982\u679c\u65e0\u7528\u7d22\u5f15\u592a\u591aI\/O\u4ee3\u4ef7\u589e\u9ad8\uff0c\u63d2\u5165\u548c\u7d22\u5f15\u5b57\u6bb5\u4fee\u6539\u5c31\u8d8a\u6162\u3002<\/li>\n<\/ul>\n<p>\u516b\u3001\u7d22\u5f15\u53ef\u4ee5\u901a\u8fc7<strong>\u7d22\u5f15\u8986\u76d6\u626b\u63cf<\/strong>\u7684\u65b9\u5f0f\u63d0\u9ad8\u6392\u5e8f\u3001\u5206\u7ec4\u548cdistinct\u7684\u901f\u5ea6\u3002<\/p>\n<ul>\n<li>\u7d22\u5f15\u8986\u76d6\u626b\u63cf\uff1a\u56e0\u4e3a\u7d22\u5f15\u4e2d\u5b58\u653e\u4e86\u7d22\u5f15\u9879\u7684\u503c\uff0c\u5728\u5b9e\u9645\u4f7f\u7528\u65f6\uff0c\u9700\u8981\u8fd4\u56de\u7d22\u5f15\u7684\u503c\u662f\u4e0d\u7528\u56de\u8868\u83b7\u53d6\u76f8\u5173\u5b57\u6bb5\u503c\u7684\uff0c\u8fd9\u6837\u53ef\u4ee5\u51cf\u5c11IO\u64cd\u4f5c\uff0c\u6548\u7387\u6700\u9ad8\u3002<\/li>\n<li>\u56e0\u4e3a\u7d22\u5f15\u5df2\u7ecf\u662f\u6709\u5e8f\u7684\u4e86\uff0c\u5728\u6392\u5e8f\u3001\u5206\u7ec4\u548cdistinct\u65f6\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528\u7d22\u5f15\u7684\u6709\u5e8f\u7ed3\u679c\u76f4\u63a5\u8fdb\u884c\u64cd\u4f5c\u3002<\/li>\n<li>\u6bd4\u5982\u7ecf\u5e38\u8981\u68c0\u7d22name\u548cpasswd\uff0c\u90a3\u4e48\u53ef\u4ee5\u628a\u8fd9\u4e24\u4e2a\u7ec4\u6210\u8054\u5408\u7d22\u5f15\uff0c<code>select passwd from tab where name like 'name';<\/code>\u8fd9\u6837\u7684\u64cd\u4f5c\u4e0d\u7528\u56de\u5230tab\u8868\u83b7\u53d6passwd\uff0c\u76f4\u63a5\u4ece\u7d22\u5f15\u4e2d\u5c31\u53ef\u4ee5\u5f97\u5230\u60f3\u8981\u7684\u503c\u3002<\/li>\n<\/ul>\n<p>\u4e5d\u3001\u7d22\u5f15\u5b57\u6bb5\u7684\u9009\u62e9\u6027\uff1a<\/p>\n<ol>\n<li>\u6ca1\u6709\u91cd\u590d\u6298\u5b57\u6bb5&#8212;-\u9009\u62e9\u6027\u6781\u597d<\/li>\n<li>\u5076\u5c14\u91cd\u590d\u7684\u5b57\u6bb5&#8212;-\u9009\u62e9\u6027\u8f83\u597d<\/li>\n<li>\u91cd\u590d\u5f88\u591a\u7684\u5b57\u6bb5&#8212;-\u9009\u62e9\u6027\u5f88\u5dee<\/li>\n<\/ol>\n<ul>\n<li>\u9009\u62e9\u6027\u5f88\u5dee\u7684\u5b57\u6bb5\u4e0d\u9002\u5408\u521b\u5efa\u5355\u5217\u7d22\u5f15\uff0c\u56e0\u4e3a\u91cd\u590d\u592a\u591a\uff0c\u53cd\u9762\u4e0d\u5982\u5168\u8868\u626b\u63cf\u6027\u80fd\u9ad8\u3002<\/li>\n<li>\u5728\u8054\u5408\u7d22\u5f15\u4e2d\u9009\u62e9\u6027\u597d\u7684\u653e\u5728\u524d\u9762\uff0c\u9009\u62e9\u6027\u5dee\u7684\u653e\u5230\u540e\u9762\uff0c\u8fd9\u6837\u53ef\u4ee5\u4f7f\u6027\u80fd\u6700\u4f18\u3002<\/li>\n<\/ul>\n<p>\u5341\u3001\u8054\u5408\u7d22\u5f15\u4e0e\u524d\u7f00\u67e5\u8be2<\/p>\n<ul>\n<li>\u8054\u5408\u7d22\u5f15\u80fd\u4e3a\u524d\u7f00\u5355\u5217\u3001\u590d\u5217\u67e5\u8be2\u63d0\u4f9b\u90a6\u52a9\u3002\u5982\uff0c\u8054\u5408\u7d22\u5f15\uff08a,b,c\uff09\u4e2d\u67093\u4e2a\u5217\uff0c\u90a3\u4e48a\u662fa,b,c\u7684\u524d\u7f00\uff0ca,b\u4e5f\u662fa,b,c\u7684\u524d\u7f00\u3002\u4e8e\u8fd9\u4e2a\u8054\u5408\u7d22\u5f15\u53ef\u4ee5\u5bf9\u5305\u542b\u524d\u7f00\u9879\u7684\u67e5\u5bfb\u63d0\u901f\uff0c\n<pre>where a=? and b=?\r\n\u6216\r\nwhere a=? and c=?\u5728\u8fd9\u91ccMYsql5.6\u4ee5\u540e\u53ef\u4ee5\u63d0\u901f\uff0c\u56e0\u4e3ac\u4e0d\u662f\u524d\u7f00\uff0c\u8fd9\u53e5\u4e2d\u8df3\u8fc7\u4e86b\u5217\uff0c\u8ba95.6\u4ee5\u524d\u7684\u7248\u672c\u53ea\u80fd\u4e3aa\u5217\u52a0\u901f\uff0cc\u5217\u4e3a\u5168\u8868\u626b\u63cf\u3002\u4f46\u57285.6\u7248\u672c\u540e\u52a0\u5165\u4e86\u65b0\u7684\u529f\u80fd\uff08\u4ec0\u4e48\u529f\u80fd\u6ca1\u8bb0\u4f4f\uff09\uff0c\u8ba9c\u5217\u4e5f\u53ef\u4ee5\u5f97\u5230\u7d22\u5f15\u52a0\u901f<\/pre>\n<\/li>\n<\/ul>\n<p>\u5341\u4e00\u3001\u4e0d\u80fd\u4f7f\u7528\u7d22\u5f15\u7684\u60c5\u51b5\uff08\u597d\u50cf\u57285.7\u7248\u672c\u91cc\u8fd9\u4e9b\u90fd\u80fd\u4f7f\u7528\u7d22\u5f15\u4e86\uff0c\u4f46\u91cd\u8bd5\u8fc7\u4e00\u6b21\u53c8\u4e0d\u884c\u4e86\uff0c\u4e0b\u6b21\u53ef\u4ee5\u4f7f\u7528\u65f6\u7528show warnings\u770b\u4e00\u4e0b\u4e3a\u4ec0\u4e48\uff01\uff09<\/p>\n<ol>\n<li>\u7d22\u5f15\u5217\u8fdb\u884c\u8fc7\u6570\u5b66\u8fd0\u7b97\u6216\u51fd\u6570\u8fd0\u7b97\uff0c\u5982\uff1awhere a+1 = 10\uff0ca\u5217\u6709\u6240\u5f15\uff0c\u4f46\u7ecf\u8fc7\u6570\u5b66\u8fd0\u7b97\u540e\u5c31\u4e0d\u80fd\u4f7f\u7528\u7d22\u5f15\uff0c\u53ea\u80fd\u4f7f\u7528\u5168\u8868\u626b\u63cf\u3002<\/li>\n<li>\u4e0d\u5305\u542b\u590d\u5408\u7d22\u5f15\u7684\u524d\u7f00\u5b57\u6bb5\uff0c\u5982\uff1aidx(a,b,c)\uff0cwhere b=? and c=?\u4e0d\u542b\u524d\u7f00\uff0c\u5982\u679c\u6709\u8fd9\u6837\u7684\u68c0\u7d22\u9700\u6c42\u5f88\u591a\uff0c\u53ef\u4ee5\u52a0\u4e00\u4e2a\uff08b\uff0cc\uff09\u7684\u7d22\u5f15\u9879\u3002<\/li>\n<li>\u524d\u7f00\u901a\u914d\uff0c\u2018_\u2019\u548c\u2018%\u2019\uff0c\u5982\uff1alike &#8216;%xxx%&#8217;\u4e0d\u80fd\u7528\u7d22\u5f15\uff0cliek &#8216;xxx%&#8217;\u53ef\u4ee5\u7528\u7d22\u5f15\u3002<\/li>\n<li>where\u6761\u4ef6\u4f7f\u7528\u4e86not, &lt;&gt;, !=<\/li>\n<li>\u5b57\u6bb5\u7c7b\u578b\u4e0d\u5339\u914d\uff0c\u5982\uff1a\u5b57\u6bb5\u7c7b\u578b\u4e3aint\u4f46\u5728\u641c\u7d22\u65f6\u4f7f\u7528\u4e86\u5b57\u7b26\uff0c\u8fd9\u79cd\u60c5\u51b5\u6709\u65f6\u5f88\u96be\u53d1\u73b0\uff0c\u56e0\u4e3a\u5f88\u6709\u53ef\u80fd\u6570\u636e\u5e93\u5185\u90e8\u4e3a\u5176\u8fdb\u884c\u7c7b\u578b\u8f6c\u6362\uff0c\u7136\u540e\u5339\u914d\u5230\u4e86\u68c0\u7d22\u9879\uff0c\u4f46\u662f\u5e76\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15\u3002<\/li>\n<li>\u5982\u679c\u68c0\u7d22<strong>\u524d\u7f00\u662f\u4e00\u4e2a\u8303\u56f4\u64cd\u4f5c<\/strong>\uff0c\u800c\u4e0d\u662f\u4e00\u4e2a\u7b49\u503c\u64cd\u4f5c\uff0c\u90a3\u4e48\u540e\u7f00\u90e8\u5206\u5c31\u65e0\u6cd5\u4f7f\u7528\u7d22\u5f15\u3002<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>\u4e00\u3001\u6bcf\u4e2a\u7d22\u5f15\u503c\u5bf9\u5e94\u4e00\u4e2a\u4e3b\u952eID\uff0c\u56e0\u4e3aInnoDB\u6839\u636e\u4e3b\u952eID\u6392\u5e8f\u5b58\u50a8\u6570\u636e\u3002 \u4e8c\u3001\u7d22\u5f15\u540c\u6837\u5360\u7528\u7a7a\u95f4\uff0c\u5b58\u5728IBD\u6587\u4ef6\u4e2d\u3002\uff08\u4e5f\u8bb8\u5427\uff01\u8fd8\u6ca1\u5f97\u5230\u786e\u8ba4\uff09 \u4e09\u3001MyIsam\u8868&#8230;<\/p>\n<p class=\"read-more\"><a class=\"btn btn-default\" href=\"https:\/\/www.5x44.cn\/?p=872\"> Read More<span class=\"screen-reader-text\">  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[37],"tags":[],"class_list":["post-872","post","type-post","status-publish","format-standard","hentry","category-mysql"],"_links":{"self":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/872","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=872"}],"version-history":[{"count":7,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/872\/revisions"}],"predecessor-version":[{"id":901,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/872\/revisions\/901"}],"wp:attachment":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=872"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=872"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=872"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}