{"id":168483,"date":"2024-11-06T12:45:19","date_gmt":"2024-11-06T04:45:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168483\/"},"modified":"2024-11-06T12:45:20","modified_gmt":"2024-11-06T04:45:20","slug":"sql-%e7%b4%84%e6%9d%9f%e5%92%8c%e5%ad%97%e6%ae%b5%e7%b4%84%e6%9d%9f%e7%9a%84%e5%89%b5%e5%bb%ba%e5%92%8c%e5%88%aa%e9%99%a4","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168483\/","title":{"rendered":"SQL \u7d04\u675f\u548c\u5b57\u6bb5\u7d04\u675f\u7684\u5275\u5efa\u548c\u522a\u9664"},"content":{"rendered":"<h1 id=\"sql-%e7%b4%84%e6%9d%9f%e5%92%8c%e5%ad%97%e6%ae%b5%e7%b4%84%e6%9d%9f%e7%9a%84%e5%89%b5%e5%bb%ba%e5%92%8c%e5%88%aa%e9%99%a4-VmQUIzHfFo\">SQL \u7d04\u675f\u548c\u5b57\u6bb5\u7d04\u675f\u7684\u5275\u5efa\u548c\u522a\u9664<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u4e00\u7a2e\u7528\u65bc\u7ba1\u7406\u548c\u64cd\u4f5c\u8cc7\u6599\u7684\u6a19\u6e96\u8a9e\u8a00\u3002SQL \u7d04\u675f\u662f\u7528\u4f86\u9650\u5236\u8cc7\u6599\u5eab\u4e2d\u8cc7\u6599\u7684\u985e\u578b\u548c\u7bc4\u570d\uff0c\u4ee5\u78ba\u4fdd\u8cc7\u6599\u7684\u5b8c\u6574\u6027\u548c\u6e96\u78ba\u6027\u3002\u672c\u6587\u5c07\u63a2\u8a0e SQL \u7d04\u675f\u548c\u5b57\u6bb5\u7d04\u675f\u7684\u5275\u5efa\u548c\u522a\u9664\uff0c\u4e26\u63d0\u4f9b\u76f8\u95dc\u7684\u7bc4\u4f8b\u548c\u4ee3\u78bc\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af-sql-%e7%b4%84%e6%9d%9f%ef%bc%9f-VmQUIzHfFo\">\u4ec0\u9ebc\u662f SQL \u7d04\u675f\uff1f<\/h2>\n<p>SQL \u7d04\u675f\u662f\u7528\u4f86\u5b9a\u7fa9\u8cc7\u6599\u8868\u4e2d\u8cc7\u6599\u7684\u898f\u5247\u3002\u9019\u4e9b\u898f\u5247\u53ef\u4ee5\u9632\u6b62\u4e0d\u6b63\u78ba\u6216\u4e0d\u4e00\u81f4\u7684\u8cc7\u6599\u9032\u5165\u8cc7\u6599\u5eab\u3002\u5e38\u898b\u7684 SQL \u7d04\u675f\u5305\u62ec\uff1a<\/p>\n<ul>\n<li><strong>NOT NULL<\/strong>\uff1a\u78ba\u4fdd\u67d0\u500b\u5b57\u6bb5\u4e0d\u80fd\u70ba\u7a7a\u3002<\/li>\n<li><strong>UNIQUE<\/strong>\uff1a\u78ba\u4fdd\u67d0\u500b\u5b57\u6bb5\u7684\u503c\u5728\u8cc7\u6599\u8868\u4e2d\u662f\u552f\u4e00\u7684\u3002<\/li>\n<li><strong>PRIMARY KEY<\/strong>\uff1a\u552f\u4e00\u6a19\u8b58\u8cc7\u6599\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\uff0c\u4e26\u4e14\u4e0d\u80fd\u70ba\u7a7a\u3002<\/li>\n<li><strong>FOREIGN KEY<\/strong>\uff1a\u7528\u65bc\u5efa\u7acb\u5169\u500b\u8cc7\u6599\u8868\u4e4b\u9593\u7684\u95dc\u806f\u3002<\/li>\n<li><strong>CHECK<\/strong>\uff1a\u78ba\u4fdd\u67d0\u500b\u5b57\u6bb5\u7684\u503c\u7b26\u5408\u7279\u5b9a\u689d\u4ef6\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%89%b5%e5%bb%ba-sql-%e7%b4%84%e6%9d%9f-VmQUIzHfFo\">\u5275\u5efa SQL \u7d04\u675f<\/h2>\n<p>\u5728\u5275\u5efa\u8cc7\u6599\u8868\u6642\uff0c\u53ef\u4ee5\u76f4\u63a5\u5728\u5b57\u6bb5\u5b9a\u7fa9\u4e2d\u6dfb\u52a0\u7d04\u675f\u3002\u4f8b\u5982\uff0c\u4ee5\u4e0b SQL \u8a9e\u53e5\u5275\u5efa\u4e86\u4e00\u500b\u540d\u70ba <code>employees<\/code> \u7684\u8cc7\u6599\u8868\uff0c\u4e26\u70ba\u5176\u5b57\u6bb5\u6dfb\u52a0\u4e86\u7d04\u675f\uff1a<\/p>\n<pre><code>CREATE TABLE employees (\n    id INT PRIMARY KEY,\n    name VARCHAR(100) NOT NULL,\n    email VARCHAR(100) UNIQUE,\n    department_id INT,\n    salary DECIMAL(10, 2) CHECK (salary &gt; 0),\n    FOREIGN KEY (department_id) REFERENCES departments(id)\n);<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff1a<\/p>\n<ul>\n<li><code>id<\/code> \u5b57\u6bb5\u662f\u4e3b\u9375\uff0c\u4e0d\u80fd\u70ba\u7a7a\u4e14\u5fc5\u9808\u552f\u4e00\u3002<\/li>\n<li><code>name<\/code> \u5b57\u6bb5\u4e0d\u80fd\u70ba\u7a7a\u3002<\/li>\n<li><code>email<\/code> \u5b57\u6bb5\u5fc5\u9808\u662f\u552f\u4e00\u7684\u3002<\/li>\n<li><code>salary<\/code> \u5b57\u6bb5\u5fc5\u9808\u5927\u65bc\u96f6\u3002<\/li>\n<li><code>department_id<\/code> \u5b57\u6bb5\u662f\u5916\u9375\uff0c\u53c3\u8003\u4e86 <code>departments<\/code> \u8cc7\u6599\u8868\u7684 <code>id<\/code> \u5b57\u6bb5\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%88%aa%e9%99%a4-sql-%e7%b4%84%e6%9d%9f-VmQUIzHfFo\">\u522a\u9664 SQL \u7d04\u675f<\/h2>\n<p>\u5982\u679c\u9700\u8981\u522a\u9664\u5df2\u5b58\u5728\u7684\u7d04\u675f\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>ALTER TABLE<\/code> \u8a9e\u53e5\u3002\u4ee5\u4e0b\u662f\u522a\u9664\u7d04\u675f\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>ALTER TABLE employees\nDROP CONSTRAINT unique_email;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c<code>unique_email<\/code> \u662f\u5728\u5275\u5efa <code>employees<\/code> \u8cc7\u6599\u8868\u6642\u70ba <code>email<\/code> \u5b57\u6bb5\u8a2d\u7f6e\u7684\u552f\u4e00\u7d04\u675f\u3002\u522a\u9664\u7d04\u675f\u5f8c\uff0c<code>email<\/code> \u5b57\u6bb5\u53ef\u4ee5\u63a5\u53d7\u91cd\u8907\u7684\u503c\u3002<\/p>\n<h2 id=\"%e7%b5%90%e8%ab%96-VmQUIzHfFo\">\u7d50\u8ad6<\/h2>\n<p>SQL \u7d04\u675f\u5728\u8cc7\u6599\u5eab\u8a2d\u8a08\u4e2d\u626e\u6f14\u8457\u91cd\u8981\u7684\u89d2\u8272\uff0c\u80fd\u5920\u78ba\u4fdd\u8cc7\u6599\u7684\u5b8c\u6574\u6027\u548c\u4e00\u81f4\u6027\u3002\u901a\u904e\u9069\u7576\u5730\u4f7f\u7528\u7d04\u675f\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u7ba1\u7406\u8cc7\u6599\u5eab\u4e2d\u7684\u8cc7\u6599\uff0c\u9632\u6b62\u4e0d\u6b63\u78ba\u7684\u8cc7\u6599\u9032\u5165\u7cfb\u7d71\u3002\u7121\u8ad6\u662f\u5728\u5275\u5efa\u8cc7\u6599\u8868\u6642\u9084\u662f\u5f8c\u671f\u7684\u7dad\u8b77\u4e2d\uff0c\u4e86\u89e3\u5982\u4f55\u5275\u5efa\u548c\u522a\u9664\u7d04\u675f\u90fd\u662f\u8cc7\u6599\u5eab\u7ba1\u7406\u8005\u5fc5\u5099\u7684\u6280\u80fd\u3002<\/p>\n<p>\u5982\u9700\u9032\u4e00\u6b65\u4e86\u89e3\u6709\u95dc <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u548c\u5176\u4ed6\u76f8\u95dc\u670d\u52d9\u7684\u4fe1\u606f\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u5728SQL\u4e2d\u5275\u5efa\u548c\u522a\u9664\u7d04\u675f\u53ca\u5b57\u6bb5\u7d04\u675f\uff0c\u4ee5\u78ba\u4fdd\u6578\u64da\u5b8c\u6574\u6027\u548c\u4e00\u81f4\u6027\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-168483","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168483","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=168483"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168483\/revisions"}],"predecessor-version":[{"id":168484,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168483\/revisions\/168484"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=168483"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=168483"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=168483"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}