{"id":1802,"date":"2025-02-18T23:01:46","date_gmt":"2025-02-18T15:01:46","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=1802"},"modified":"2025-02-18T23:01:46","modified_gmt":"2025-02-18T15:01:46","slug":"mysql-%e5%a4%84%e7%90%86%e9%87%8d%e5%a4%8d%e6%95%b0%e6%8d%ae","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/02\/18\/mysql-%e5%a4%84%e7%90%86%e9%87%8d%e5%a4%8d%e6%95%b0%e6%8d%ae\/","title":{"rendered":"MySQL \u5904\u7406\u91cd\u590d\u6570\u636e"},"content":{"rendered":"\n<p>\u5728 MySQL \u4e2d\uff0c\u5904\u7406\u91cd\u590d\u6570\u636e\u662f\u5e38\u89c1\u7684\u4efb\u52a1\uff0c\u5c24\u5176\u5728\u63d2\u5165\u6570\u636e\u65f6\uff0c\u53ef\u80fd\u4f1a\u51fa\u73b0\u91cd\u590d\u8bb0\u5f55\u3002MySQL \u63d0\u4f9b\u4e86\u591a\u79cd\u65b9\u6cd5\u6765\u67e5\u627e\u3001\u5220\u9664\u6216\u907f\u514d\u63d2\u5165\u91cd\u590d\u6570\u636e\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u89c1\u7684\u5904\u7406\u91cd\u590d\u6570\u636e\u7684\u65b9\u6cd5\u53ca\u5b9e\u4f8b\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1. <strong>\u67e5\u627e\u91cd\u590d\u6570\u636e<\/strong><\/h3>\n\n\n\n<p>\u67e5\u627e\u91cd\u590d\u6570\u636e\u901a\u5e38\u901a\u8fc7 <code>GROUP BY<\/code> \u548c <code>HAVING<\/code> \u5b50\u53e5\u5b9e\u73b0\u3002\u8fd9\u4e9b\u5b50\u53e5\u53ef\u4ee5\u5e2e\u52a9\u4f60\u8bc6\u522b\u5728\u67d0\u4e2a\u6216\u591a\u4e2a\u5217\u4e0a\u5177\u6709\u76f8\u540c\u503c\u7684\u884c\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u793a\u4f8b\uff1a\u67e5\u627e\u91cd\u590d\u7684\u59d3\u540d<\/h4>\n\n\n\n<p>\u5047\u8bbe\u6709\u4e00\u4e2a <code>employees<\/code> \u8868\uff0c\u7ed3\u6784\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>CREATE TABLE employees (\n    emp_id INT AUTO_INCREMENT PRIMARY KEY,\n    emp_name VARCHAR(100),\n    emp_salary DECIMAL(10, 2)\n);<\/code><\/pre>\n\n\n\n<p>\u63d2\u5165\u4e00\u4e9b\u6570\u636e\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>INSERT INTO employees (emp_name, emp_salary)\nVALUES\n('John Doe', 50000.00),\n('Jane Smith', 55000.00),\n('John Doe', 50000.00),\n('Alice Brown', 60000.00),\n('Jane Smith', 55000.00);<\/code><\/pre>\n\n\n\n<p>\u8981\u67e5\u627e\u91cd\u590d\u7684 <code>emp_name<\/code> \u548c <code>emp_salary<\/code>\uff0c\u53ef\u4ee5\u4f7f\u7528\u5982\u4e0b\u67e5\u8be2\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>SELECT emp_name, emp_salary, COUNT(*)\nFROM employees\nGROUP BY emp_name, emp_salary\nHAVING COUNT(*) &gt; 1;<\/code><\/pre>\n\n\n\n<p>\u67e5\u8be2\u7ed3\u679c\u5c06\u8fd4\u56de\u6240\u6709\u5177\u6709\u91cd\u590d\u59d3\u540d\u548c\u85aa\u8d44\u7684\u8bb0\u5f55\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>emp_name<\/th><th>emp_salary<\/th><th>COUNT(*)<\/th><\/tr><\/thead><tbody><tr><td>John Doe<\/td><td>50000.00<\/td><td>2<\/td><\/tr><tr><td>Jane Smith<\/td><td>55000.00<\/td><td>2<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">2. <strong>\u5220\u9664\u91cd\u590d\u6570\u636e<\/strong><\/h3>\n\n\n\n<p>\u5220\u9664\u91cd\u590d\u6570\u636e\u53ef\u4ee5\u4f7f\u7528 <code>DELETE<\/code> \u8bed\u53e5\u7ed3\u5408\u5b50\u67e5\u8be2\uff0c\u786e\u4fdd\u53ea\u4fdd\u7559\u4e00\u6761\u8bb0\u5f55\uff0c\u5220\u9664\u5176\u4ed6\u91cd\u590d\u7684\u884c\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u793a\u4f8b\uff1a\u5220\u9664\u91cd\u590d\u7684\u5458\u5de5\u8bb0\u5f55<\/h4>\n\n\n\n<p>\u5982\u679c\u4f60\u5e0c\u671b\u5220\u9664 <code>emp_name<\/code> \u548c <code>emp_salary<\/code> \u76f8\u540c\u7684\u91cd\u590d\u8bb0\u5f55\uff0c\u5e76\u4e14\u53ea\u4fdd\u7559\u4e00\u6761\u8bb0\u5f55\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b SQL\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>DELETE e1\nFROM employees e1\nJOIN employees e2\nON e1.emp_name = e2.emp_name AND e1.emp_salary = e2.emp_salary\nWHERE e1.emp_id &gt; e2.emp_id;<\/code><\/pre>\n\n\n\n<p>\u6b64\u67e5\u8be2\u7684\u5de5\u4f5c\u539f\u7406\u662f\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4f7f\u7528 <code>JOIN<\/code> \u64cd\u4f5c\u5c06\u8868\u4e0e\u81ea\u8eab\u8fde\u63a5\u3002<\/li>\n\n\n\n<li>\u4f7f\u7528 <code>WHERE e1.emp_id > e2.emp_id<\/code> \u6761\u4ef6\u6765\u786e\u4fdd\u5220\u9664\u5177\u6709\u8f83\u9ad8 <code>emp_id<\/code> \u7684\u91cd\u590d\u884c\u3002<\/li>\n\n\n\n<li>\u4fdd\u7559\u5177\u6709\u8f83\u5c0f <code>emp_id<\/code> \u7684\u8bb0\u5f55\uff0c\u5373\u6bcf\u7ec4\u91cd\u590d\u6570\u636e\u53ea\u4fdd\u7559\u6700\u65e9\u63d2\u5165\u7684\u90a3\u6761\u3002<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">3. <strong>\u4f7f\u7528 <code>DISTINCT<\/code> \u907f\u514d\u91cd\u590d\u63d2\u5165<\/strong><\/h3>\n\n\n\n<p>\u5f53\u4ece\u4e00\u4e2a\u8868\u4e2d\u67e5\u8be2\u5e76\u63d2\u5165\u6570\u636e\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>DISTINCT<\/code> \u6765\u907f\u514d\u63d2\u5165\u91cd\u590d\u6570\u636e\u3002<code>DISTINCT<\/code> \u7528\u4e8e\u4ece\u7ed3\u679c\u96c6\u4e2d\u53bb\u9664\u91cd\u590d\u7684\u884c\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u793a\u4f8b\uff1a\u4f7f\u7528 <code>DISTINCT<\/code> \u63d2\u5165\u6570\u636e<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>INSERT INTO employees (emp_name, emp_salary)\nSELECT DISTINCT emp_name, emp_salary\nFROM employees_backup;<\/code><\/pre>\n\n\n\n<p>\u8fd9\u6837\uff0c<code>employees_backup<\/code> \u8868\u4e2d\u7684\u91cd\u590d\u8bb0\u5f55\u5c06\u4e0d\u4f1a\u88ab\u63d2\u5165\u5230 <code>employees<\/code> \u8868\u4e2d\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4. <strong>\u4f7f\u7528 <code>INSERT IGNORE<\/code> \u63d2\u5165\u6570\u636e\u65f6\u907f\u514d\u91cd\u590d<\/strong><\/h3>\n\n\n\n<p>\u5728\u63d2\u5165\u6570\u636e\u65f6\uff0c\u4f7f\u7528 <code>INSERT IGNORE<\/code> \u53ef\u4ee5\u907f\u514d\u7531\u4e8e\u91cd\u590d\u7684\u952e\u503c\uff08\u5982\u4e3b\u952e\u6216\u552f\u4e00\u7d22\u5f15\uff09\u5bfc\u81f4\u7684\u63d2\u5165\u9519\u8bef\u3002\u5982\u679c\u63d2\u5165\u7684\u6570\u636e\u4e0e\u73b0\u6709\u6570\u636e\u91cd\u590d\uff0c<code>INSERT IGNORE<\/code> \u5c06\u4f1a\u5ffd\u7565\u91cd\u590d\u7684\u884c\uff0c\u800c\u4e0d\u4f1a\u629b\u51fa\u9519\u8bef\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u793a\u4f8b\uff1a\u4f7f\u7528 <code>INSERT IGNORE<\/code> \u63d2\u5165\u6570\u636e<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>INSERT IGNORE INTO employees (emp_name, emp_salary)\nVALUES ('John Doe', 50000.00), ('Jane Smith', 55000.00);<\/code><\/pre>\n\n\n\n<p>\u5982\u679c <code>employees<\/code> \u8868\u4e2d\u5df2\u7ecf\u5b58\u5728 <code>emp_name<\/code> \u4e3a <code>'John Doe'<\/code> \u6216 <code>'Jane Smith'<\/code> \u7684\u8bb0\u5f55\uff0c\u8fd9\u4e9b\u8bb0\u5f55\u5c06\u88ab\u5ffd\u7565\uff0c\u4e0d\u4f1a\u63d2\u5165\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">5. <strong>\u4f7f\u7528 <code>REPLACE INTO<\/code> \u66ff\u4ee3\u91cd\u590d\u6570\u636e<\/strong><\/h3>\n\n\n\n<p><code>REPLACE INTO<\/code> \u662f MySQL \u7684\u4e00\u4e2a\u6269\u5c55\u547d\u4ee4\uff0c\u5b83\u4f1a\u68c0\u67e5\u662f\u5426\u5b58\u5728\u5177\u6709\u76f8\u540c\u4e3b\u952e\u6216\u552f\u4e00\u7d22\u5f15\u7684\u884c\u3002\u5982\u679c\u6709\uff0cMySQL \u4f1a\u5220\u9664\u8be5\u884c\u5e76\u63d2\u5165\u65b0\u7684\u884c\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u793a\u4f8b\uff1a\u4f7f\u7528 <code>REPLACE INTO<\/code> \u66ff\u4ee3\u6570\u636e<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>REPLACE INTO employees (emp_id, emp_name, emp_salary)\nVALUES (1, 'John Doe', 55000.00);<\/code><\/pre>\n\n\n\n<p>\u5982\u679c <code>emp_id<\/code> \u4e3a <code>1<\/code> \u7684\u8bb0\u5f55\u5df2\u7ecf\u5b58\u5728\uff0cMySQL \u5c06\u5220\u9664\u8be5\u8bb0\u5f55\u5e76\u63d2\u5165\u65b0\u7684\u8bb0\u5f55\u3002\u5982\u679c\u4e0d\u5b58\u5728\uff0c\u5219\u4f1a\u63d2\u5165\u4e00\u6761\u65b0\u8bb0\u5f55\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">6. <strong>\u521b\u5efa\u552f\u4e00\u7d22\u5f15\u9632\u6b62\u91cd\u590d\u6570\u636e\u63d2\u5165<\/strong><\/h3>\n\n\n\n<p>\u4e3a\u4e86\u907f\u514d\u91cd\u590d\u6570\u636e\u7684\u63d2\u5165\uff0c\u53ef\u4ee5\u5728\u8868\u4e2d\u521b\u5efa\u552f\u4e00\u7d22\u5f15\u3002\u552f\u4e00\u7d22\u5f15\u4f1a\u786e\u4fdd\u63d2\u5165\u6570\u636e\u65f6\u67d0\u4e9b\u5217\u7684\u7ec4\u5408\u503c\u662f\u552f\u4e00\u7684\uff0c\u4ece\u800c\u9632\u6b62\u91cd\u590d\u8bb0\u5f55\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u793a\u4f8b\uff1a\u521b\u5efa\u552f\u4e00\u7d22\u5f15<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>CREATE UNIQUE INDEX idx_emp_name_salary ON employees (emp_name, emp_salary);<\/code><\/pre>\n\n\n\n<p>\u8fd9\u6837\uff0c\u5982\u679c\u5c1d\u8bd5\u63d2\u5165\u5177\u6709\u76f8\u540c <code>emp_name<\/code> \u548c <code>emp_salary<\/code> \u7684\u8bb0\u5f55\uff0cMySQL \u4f1a\u62d2\u7edd\u63d2\u5165\uff0c\u5e76\u8fd4\u56de\u4e00\u4e2a\u9519\u8bef\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">7. <strong>\u603b\u7ed3<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u67e5\u627e\u91cd\u590d\u6570\u636e<\/strong>\uff1a\u4f7f\u7528 <code>GROUP BY<\/code> \u548c <code>HAVING<\/code> \u5b50\u53e5\u6765\u67e5\u627e\u5177\u6709\u76f8\u540c\u503c\u7684\u8bb0\u5f55\u3002<\/li>\n\n\n\n<li><strong>\u5220\u9664\u91cd\u590d\u6570\u636e<\/strong>\uff1a\u4f7f\u7528 <code>DELETE<\/code> \u8bed\u53e5\u7ed3\u5408 <code>JOIN<\/code> \u6765\u5220\u9664\u91cd\u590d\u6570\u636e\uff0c\u901a\u5e38\u901a\u8fc7\u6bd4\u8f83\u4e3b\u952e\uff08\u5982 <code>emp_id<\/code>\uff09\u6765\u4fdd\u7559\u4e00\u6761\u8bb0\u5f55\u3002<\/li>\n\n\n\n<li><strong>\u907f\u514d\u91cd\u590d\u63d2\u5165<\/strong>\uff1a\u4f7f\u7528 <code>DISTINCT<\/code>\u3001<code>INSERT IGNORE<\/code> \u6216 <code>REPLACE INTO<\/code> \u6765\u907f\u514d\u63d2\u5165\u91cd\u590d\u6570\u636e\u3002<\/li>\n\n\n\n<li><strong>\u521b\u5efa\u552f\u4e00\u7d22\u5f15<\/strong>\uff1a\u901a\u8fc7\u521b\u5efa\u552f\u4e00\u7d22\u5f15\u6765\u786e\u4fdd\u6570\u636e\u7684\u552f\u4e00\u6027\uff0c\u9632\u6b62\u91cd\u590d\u6570\u636e\u7684\u63d2\u5165\u3002<\/li>\n<\/ul>\n\n\n\n<p>\u5904\u7406\u91cd\u590d\u6570\u636e\u7684\u65b9\u5f0f\u5f88\u591a\uff0c\u5177\u4f53\u9009\u62e9\u54ea\u79cd\u65b9\u6cd5\u53d6\u51b3\u4e8e\u5b9e\u9645\u9700\u6c42\uff0c\u4f8b\u5982\u662f\u5426\u9700\u8981\u4fdd\u7559\u4e00\u6761\u8bb0\u5f55\u6216\u662f\u5b8c\u5168\u5220\u9664\u91cd\u590d\u6570\u636e\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728 MySQL \u4e2d\uff0c\u5904\u7406\u91cd\u590d\u6570\u636e\u662f\u5e38\u89c1\u7684\u4efb\u52a1\uff0c\u5c24\u5176\u5728\u63d2\u5165\u6570\u636e\u65f6\uff0c\u53ef\u80fd\u4f1a\u51fa\u73b0\u91cd\u590d\u8bb0\u5f55\u3002MySQL \u63d0\u4f9b\u4e86\u591a\u79cd\u65b9\u6cd5 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[35],"tags":[],"class_list":["post-1802","post","type-post","status-publish","format-standard","hentry","category-mysql"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1802","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=1802"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1802\/revisions"}],"predecessor-version":[{"id":1803,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/1802\/revisions\/1803"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=1802"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=1802"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=1802"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}