{"id":1991,"date":"2025-06-14T19:00:27","date_gmt":"2025-06-14T11:00:27","guid":{"rendered":"https:\/\/note.ui11.cc\/?p=1991"},"modified":"2025-06-14T19:00:27","modified_gmt":"2025-06-14T11:00:27","slug":"mysql-%e6%a0%b8%e5%bf%83%e7%9f%a5%e8%af%86%e8%af%a6%e8%a7%a3","status":"publish","type":"post","link":"https:\/\/note.ui11.cc\/index.php\/2025\/06\/14\/mysql-%e6%a0%b8%e5%bf%83%e7%9f%a5%e8%af%86%e8%af%a6%e8%a7%a3\/","title":{"rendered":"MySQL \u6838\u5fc3\u77e5\u8bc6\u8be6\u89e3"},"content":{"rendered":"\n<h4 class=\"wp-block-heading\">\u4e00\u3001SQL \u57fa\u7840\u8bed\u53e5<\/h4>\n\n\n\n<h5 class=\"wp-block-heading\">1. \u6570\u636e\u5b9a\u4e49\u8bed\u8a00\uff08DDL\uff09<\/h5>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u521b\u5efa\u6570\u636e\u5e93\nCREATE DATABASE IF NOT EXISTS mydb;\n\n-- \u4f7f\u7528\u6570\u636e\u5e93\nUSE mydb;\n\n-- \u521b\u5efa\u8868\nCREATE TABLE users (\n    id INT PRIMARY KEY AUTO_INCREMENT,\n    username VARCHAR(50) NOT NULL UNIQUE,\n    email VARCHAR(100) NOT NULL,\n    age INT CHECK (age &gt; 0),\n    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP\n);\n\n-- \u4fee\u6539\u8868\u7ed3\u6784\nALTER TABLE users ADD COLUMN phone VARCHAR(20);\nALTER TABLE users MODIFY COLUMN age TINYINT;\nALTER TABLE users DROP COLUMN phone;\n\n-- \u5220\u9664\u8868\nDROP TABLE IF EXISTS users;\n<\/code><\/pre>\n\n\n\n<h5 class=\"wp-block-heading\">2. \u6570\u636e\u64cd\u4f5c\u8bed\u8a00\uff08DML\uff09<\/h5>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u63d2\u5165\u6570\u636e\nINSERT INTO users (username, email, age) VALUES \n('john', 'john@example.com', 25),\n('mary', 'mary@example.com', 30);\n\n-- \u67e5\u8be2\u6570\u636e\nSELECT * FROM users WHERE age &gt; 20 ORDER BY created_at DESC LIMIT 10;\n\n-- \u66f4\u65b0\u6570\u636e\nUPDATE users SET age = age + 1 WHERE username = 'john';\n\n-- \u5220\u9664\u6570\u636e\nDELETE FROM users WHERE username = 'john';\n<\/code><\/pre>\n\n\n\n<h5 class=\"wp-block-heading\">3. \u6570\u636e\u67e5\u8be2\u8bed\u8a00\uff08DQL\uff09<\/h5>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u8fde\u63a5\u67e5\u8be2\nSELECT u.username, o.order_id \nFROM users u \nJOIN orders o ON u.id = o.user_id;\n\n-- \u5b50\u67e5\u8be2\nSELECT username FROM users \nWHERE id IN (SELECT user_id FROM orders WHERE amount &gt; 100);\n\n-- \u805a\u5408\u51fd\u6570\nSELECT COUNT(*), AVG(age), MAX(age), MIN(age) \nFROM users;\n\n-- \u5206\u7ec4\u67e5\u8be2\nSELECT age, COUNT(*) \nFROM users \nGROUP BY age \nHAVING COUNT(*) &gt; 1;\n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\">\u4e8c\u3001MySQL \u5b58\u50a8\u5f15\u64ce<\/h4>\n\n\n\n<p>MySQL \u652f\u6301\u591a\u79cd\u5b58\u50a8\u5f15\u64ce\uff0c\u6700\u5e38\u7528\u7684\u662f&nbsp;<strong>InnoDB<\/strong>&nbsp;\u548c&nbsp;<strong>MyISAM<\/strong>\uff0c\u533a\u522b\u5982\u4e0b\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u7279\u6027<\/th><th>InnoDB<\/th><th>MyISAM<\/th><\/tr><\/thead><tbody><tr><td><strong>\u4e8b\u52a1\u652f\u6301<\/strong><\/td><td>\u652f\u6301\uff08ACID\uff09<\/td><td>\u4e0d\u652f\u6301<\/td><\/tr><tr><td><strong>\u5916\u952e\u652f\u6301<\/strong><\/td><td>\u652f\u6301<\/td><td>\u4e0d\u652f\u6301<\/td><\/tr><tr><td><strong>\u9501\u7c92\u5ea6<\/strong><\/td><td>\u884c\u7ea7\u9501\uff08\u9002\u5408\u9ad8\u5e76\u53d1\uff09<\/td><td>\u8868\u7ea7\u9501<\/td><\/tr><tr><td><strong>\u7d22\u5f15\u4e0e\u6570\u636e\u5b58\u50a8<\/strong><\/td><td>\u805a\u7c07\u7d22\u5f15\uff08\u7d22\u5f15\u548c\u6570\u636e\u5b58\u50a8\u5728\u4e00\u8d77\uff09<\/td><td>\u975e\u805a\u7c07\u7d22\u5f15\uff08\u7d22\u5f15\u548c\u6570\u636e\u5206\u79bb\uff09<\/td><\/tr><tr><td><strong>\u5168\u6587\u7d22\u5f15<\/strong><\/td><td>5.6+ \u652f\u6301<\/td><td>\u652f\u6301<\/td><\/tr><tr><td><strong>\u5d29\u6e83\u6062\u590d<\/strong><\/td><td>\u652f\u6301<\/td><td>\u4e0d\u652f\u6301<\/td><\/tr><tr><td><strong>\u5b58\u50a8\u9650\u5236<\/strong><\/td><td>64TB<\/td><td>256TB<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><strong>\u9009\u62e9\u5efa\u8bae<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>InnoDB\uff1a\u9002\u5408\u9700\u8981\u4e8b\u52a1\u3001\u9ad8\u5e76\u53d1\u3001\u5916\u952e\u7684\u573a\u666f\uff08\u5982\u7535\u5546\u3001\u91d1\u878d\uff09<\/li>\n\n\n\n<li>MyISAM\uff1a\u9002\u5408\u8bfb\u591a\u5199\u5c11\u3001\u4e0d\u9700\u8981\u4e8b\u52a1\u7684\u573a\u666f\uff08\u5982\u65e5\u5fd7\u3001\u7edf\u8ba1\uff09<\/li>\n<\/ul>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u67e5\u770b\u652f\u6301\u7684\u5b58\u50a8\u5f15\u64ce\nSHOW ENGINES;\n\n-- \u521b\u5efa\u8868\u65f6\u6307\u5b9a\u5b58\u50a8\u5f15\u64ce\nCREATE TABLE mytable (\n    id INT PRIMARY KEY\n) ENGINE=InnoDB;\n\n-- \u4fee\u6539\u8868\u7684\u5b58\u50a8\u5f15\u64ce\nALTER TABLE mytable ENGINE=MyISAM;\n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\">\u4e09\u3001\u4e8b\u52a1\u7ba1\u7406<\/h4>\n\n\n\n<h5 class=\"wp-block-heading\">1. \u4e8b\u52a1\u7684\u56db\u5927\u7279\u6027\uff08ACID\uff09<\/h5>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u539f\u5b50\u6027\uff08Atomicity\uff09<\/strong>\uff1a\u4e8b\u52a1\u4e2d\u7684\u64cd\u4f5c\u8981\u4e48\u5168\u90e8\u6210\u529f\uff0c\u8981\u4e48\u5168\u90e8\u5931\u8d25<\/li>\n\n\n\n<li><strong>\u4e00\u81f4\u6027\uff08Consistency\uff09<\/strong>\uff1a\u4e8b\u52a1\u6267\u884c\u524d\u540e\u6570\u636e\u5e93\u72b6\u6001\u4fdd\u6301\u4e00\u81f4<\/li>\n\n\n\n<li><strong>\u9694\u79bb\u6027\uff08Isolation\uff09<\/strong>\uff1a\u591a\u4e2a\u4e8b\u52a1\u76f8\u4e92\u9694\u79bb\uff0c\u4e92\u4e0d\u5e72\u6270<\/li>\n\n\n\n<li><strong>\u6301\u4e45\u6027\uff08Durability\uff09<\/strong>\uff1a\u4e8b\u52a1\u63d0\u4ea4\u540e\uff0c\u6570\u636e\u6c38\u4e45\u4fdd\u5b58<\/li>\n<\/ul>\n\n\n\n<h5 class=\"wp-block-heading\">2. \u4e8b\u52a1\u63a7\u5236\u8bed\u53e5<\/h5>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u663e\u5f0f\u5f00\u542f\u4e8b\u52a1\nSTART TRANSACTION;\n\n-- \u793a\u4f8b\u4e1a\u52a1\u903b\u8f91\nINSERT INTO accounts (user_id, balance) VALUES (1, 1000);\nUPDATE accounts SET balance = balance - 500 WHERE user_id = 1;\nUPDATE accounts SET balance = balance + 500 WHERE user_id = 2;\n\n-- \u63d0\u4ea4\u4e8b\u52a1\nCOMMIT;\n\n-- \u56de\u6eda\u4e8b\u52a1\nROLLBACK;\n\n-- \u8bbe\u7f6e\u4fdd\u5b58\u70b9\nSAVEPOINT sp1;\nROLLBACK TO sp1;\n<\/code><\/pre>\n\n\n\n<h5 class=\"wp-block-heading\">3. \u4e8b\u52a1\u9694\u79bb\u7ea7\u522b<\/h5>\n\n\n\n<p>MySQL \u652f\u6301\u56db\u79cd\u9694\u79bb\u7ea7\u522b\uff0c\u901a\u8fc7&nbsp;<code>SET TRANSACTION ISOLATION LEVEL<\/code>&nbsp;\u8bbe\u7f6e\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u9694\u79bb\u7ea7\u522b<\/th><th>\u810f\u8bfb<\/th><th>\u4e0d\u53ef\u91cd\u590d\u8bfb<\/th><th>\u5e7b\u8bfb<\/th><\/tr><\/thead><tbody><tr><td><strong>READ UNCOMMITTED<\/strong><\/td><td>\u5141\u8bb8<\/td><td>\u5141\u8bb8<\/td><td>\u5141\u8bb8<\/td><\/tr><tr><td><strong>READ COMMITTED<\/strong><\/td><td>\u7981\u6b62<\/td><td>\u5141\u8bb8<\/td><td>\u5141\u8bb8<\/td><\/tr><tr><td><strong>REPEATABLE READ<\/strong><\/td><td>\u7981\u6b62<\/td><td>\u7981\u6b62<\/td><td>\u5141\u8bb8<\/td><\/tr><tr><td><strong>SERIALIZABLE<\/strong><\/td><td>\u7981\u6b62<\/td><td>\u7981\u6b62<\/td><td>\u7981\u6b62<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u67e5\u770b\u5f53\u524d\u9694\u79bb\u7ea7\u522b\nSELECT @@tx_isolation;\n\n-- \u8bbe\u7f6e\u4f1a\u8bdd\u9694\u79bb\u7ea7\u522b\nSET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;\n<\/code><\/pre>\n\n\n\n<p><strong>InnoDB \u9ed8\u8ba4\u9694\u79bb\u7ea7\u522b<\/strong>\uff1aREPEATABLE READ\uff08\u901a\u8fc7 MVCC \u89e3\u51b3\u5e7b\u8bfb\uff09<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">4. \u5904\u7406\u6b7b\u9501<\/h5>\n\n\n\n<p>\u6b7b\u9501\u662f\u6307\u4e24\u4e2a\u6216\u591a\u4e2a\u4e8b\u52a1\u4e92\u76f8\u7b49\u5f85\u5bf9\u65b9\u91ca\u653e\u9501\u7684\u60c5\u51b5\u3002<\/p>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u67e5\u770b\u6b7b\u9501\u65e5\u5fd7\nSHOW ENGINE INNODB STATUS;\n\n-- \u8bbe\u7f6e\u4e8b\u52a1\u8d85\u65f6\u65f6\u95f4\nSET innodb_lock_wait_timeout = 50;\n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\">\u56db\u3001\u9ad8\u7ea7\u7279\u6027<\/h4>\n\n\n\n<h5 class=\"wp-block-heading\">1. \u7d22\u5f15\u4f18\u5316<\/h5>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u521b\u5efa\u666e\u901a\u7d22\u5f15\nCREATE INDEX idx_username ON users (username);\n\n-- \u521b\u5efa\u552f\u4e00\u7d22\u5f15\nCREATE UNIQUE INDEX idx_email ON users (email);\n\n-- \u521b\u5efa\u590d\u5408\u7d22\u5f15\nCREATE INDEX idx_name_age ON users (username, age);\n\n-- \u67e5\u770b\u67e5\u8be2\u6267\u884c\u8ba1\u5212\nEXPLAIN SELECT * FROM users WHERE username = 'john';\n<\/code><\/pre>\n\n\n\n<h5 class=\"wp-block-heading\">2. \u89c6\u56fe<\/h5>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u521b\u5efa\u89c6\u56fe\nCREATE VIEW user_orders AS\nSELECT u.username, o.order_id, o.amount\nFROM users u\nJOIN orders o ON u.id = o.user_id;\n\n-- \u67e5\u8be2\u89c6\u56fe\nSELECT * FROM user_orders;\n<\/code><\/pre>\n\n\n\n<h5 class=\"wp-block-heading\">3. \u5b58\u50a8\u8fc7\u7a0b<\/h5>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u521b\u5efa\u5b58\u50a8\u8fc7\u7a0b\nDELIMITER $$\nCREATE PROCEDURE GetUserCount(OUT total INT)\nBEGIN\n    SELECT COUNT(*) INTO total FROM users;\nEND$$\nDELIMITER ;\n\n-- \u8c03\u7528\u5b58\u50a8\u8fc7\u7a0b\nCALL GetUserCount(@total);\nSELECT @total;\n<\/code><\/pre>\n\n\n\n<h5 class=\"wp-block-heading\">4. \u89e6\u53d1\u5668<\/h5>\n\n\n\n<p>sql<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u521b\u5efa\u89e6\u53d1\u5668\nCREATE TRIGGER before_user_insert\nBEFORE INSERT ON users\nFOR EACH ROW\nBEGIN\n    SET NEW.created_at = NOW();\nEND;\n<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\">\u4e94\u3001\u6027\u80fd\u4f18\u5316\u5efa\u8bae<\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u7d22\u5f15\u4f18\u5316<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u4e3a\u7ecf\u5e38\u7528\u4e8e\u67e5\u8be2\u6761\u4ef6\u548c\u6392\u5e8f\u7684\u5b57\u6bb5\u521b\u5efa\u7d22\u5f15<\/li>\n\n\n\n<li>\u907f\u514d\u8fc7\u591a\u7d22\u5f15\uff08\u4f1a\u5f71\u54cd\u5199\u6027\u80fd\uff09<\/li>\n\n\n\n<li>\u4f7f\u7528\u590d\u5408\u7d22\u5f15\u65f6\u6ce8\u610f\u6700\u5de6\u524d\u7f00\u539f\u5219<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u67e5\u8be2\u4f18\u5316<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u907f\u514d\u00a0<code>SELECT *<\/code>\uff0c\u53ea\u67e5\u8be2\u9700\u8981\u7684\u5b57\u6bb5<\/li>\n\n\n\n<li>\u4f7f\u7528\u00a0<code>EXPLAIN<\/code>\u00a0\u5206\u6790\u67e5\u8be2\u6267\u884c\u8ba1\u5212<\/li>\n\n\n\n<li>\u907f\u514d\u5b50\u67e5\u8be2\uff0c\u5c3d\u91cf\u7528\u8fde\u63a5\u67e5\u8be2\u66ff\u4ee3<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u67b6\u6784\u4f18\u5316<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u5206\u5e93\u5206\u8868\uff08\u5782\u76f4\u62c6\u5206\u548c\u6c34\u5e73\u62c6\u5206\uff09<\/li>\n\n\n\n<li>\u8bfb\u5199\u5206\u79bb<\/li>\n\n\n\n<li>\u9002\u5f53\u4f7f\u7528\u7f13\u5b58\uff08\u5982 Redis\uff09<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u914d\u7f6e\u4f18\u5316<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u8c03\u6574\u00a0<code>innodb_buffer_pool_size<\/code>\uff08\u5efa\u8bae\u4e3a\u7269\u7406\u5185\u5b58\u7684 70-80%\uff09<\/li>\n\n\n\n<li>\u4f18\u5316\u65e5\u5fd7\u914d\u7f6e\uff08<code>innodb_log_file_size<\/code>\uff09<\/li>\n\n\n\n<li>\u5b9a\u671f\u6267\u884c\u00a0<code>OPTIMIZE TABLE<\/code>\u00a0\u6574\u7406\u788e\u7247<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<p>\u901a\u8fc7\u638c\u63e1\u4ee5\u4e0a\u5185\u5bb9\uff0c\u4f60\u53ef\u4ee5\u719f\u7ec3\u7f16\u5199 MySQL \u8bed\u53e5\uff0c\u7406\u89e3\u4e0d\u540c\u5b58\u50a8\u5f15\u64ce\u7684\u9002\u7528\u573a\u666f\uff0c\u5e76\u7075\u6d3b\u8fd0\u7528\u4e8b\u52a1\u7279\u6027\u5904\u7406\u590d\u6742\u4e1a\u52a1\u903b\u8f91\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e00\u3001SQL \u57fa\u7840\u8bed\u53e5 1. \u6570\u636e\u5b9a\u4e49\u8bed\u8a00\uff08DDL\uff09 sql 2. \u6570\u636e\u64cd\u4f5c\u8bed\u8a00\uff08DML\uff09 sql 3. \u6570\u636e\u67e5 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1991","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/posts\/1991","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/comments?post=1991"}],"version-history":[{"count":1,"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/posts\/1991\/revisions"}],"predecessor-version":[{"id":1992,"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/posts\/1991\/revisions\/1992"}],"wp:attachment":[{"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/media?parent=1991"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/categories?post=1991"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/note.ui11.cc\/index.php\/wp-json\/wp\/v2\/tags?post=1991"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}