{"id":168385,"date":"2024-11-06T11:56:22","date_gmt":"2024-11-06T03:56:22","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168385\/"},"modified":"2024-11-06T11:56:23","modified_gmt":"2024-11-06T03:56:23","slug":"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%ad%97%e6%ae%b5%e9%95%b7%e5%ba%a6%e4%bf%ae%e6%94%b9%e6%96%b9%e6%b3%95%e8%a9%b3%e8%a7%a3-sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%bf%ae%e6%94%b9%e5%ad%97%e6%ae%b5%e9%95%b7","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168385\/","title":{"rendered":"SQL \u6578\u64da\u5eab\u5b57\u6bb5\u9577\u5ea6\u4fee\u6539\u65b9\u6cd5\u8a73\u89e3 (sql \u6578\u64da\u5eab\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6)"},"content":{"rendered":"<h1 id=\"sql-%e6%95%b8%e6%93%9a%e5%ba%ab%e5%ad%97%e6%ae%b5%e9%95%b7%e5%ba%a6%e4%bf%ae%e6%94%b9%e6%96%b9%e6%b3%95%e8%a9%b3%e8%a7%a3-mcFxKvFkPQ\">SQL \u6578\u64da\u5eab\u5b57\u6bb5\u9577\u5ea6\u4fee\u6539\u65b9\u6cd5\u8a73\u89e3<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u5b57\u6bb5\u7684\u9577\u5ea6\u662f\u8a2d\u8a08\u548c\u7dad\u8b77\u6578\u64da\u5eab\u6642\u9700\u8981\u8003\u616e\u7684\u91cd\u8981\u56e0\u7d20\u3002\u96a8\u8457\u696d\u52d9\u9700\u6c42\u7684\u8b8a\u5316\uff0c\u53ef\u80fd\u9700\u8981\u5c0d\u73fe\u6709\u5b57\u6bb5\u7684\u9577\u5ea6\u9032\u884c\u4fee\u6539\u3002\u672c\u6587\u5c07\u8a73\u7d30\u4ecb\u7d39\u5982\u4f55\u5728 SQL \u6578\u64da\u5eab\u4e2d\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\uff0c\u5305\u62ec\u4e0d\u540c\u6578\u64da\u5eab\u7cfb\u7d71\u7684\u5177\u9ad4\u64cd\u4f5c\u65b9\u6cd5\u3002<\/p>\n<h2 id=\"%e7%82%ba%e4%bb%80%e9%ba%bc%e9%9c%80%e8%a6%81%e4%bf%ae%e6%94%b9%e5%ad%97%e6%ae%b5%e9%95%b7%e5%ba%a6-mcFxKvFkPQ\">\u70ba\u4ec0\u9ebc\u9700\u8981\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6<\/h2>\n<p>\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\u7684\u539f\u56e0\u6709\u5f88\u591a\uff0c\u4e3b\u8981\u5305\u62ec\uff1a<\/p>\n<ul>\n<li>\u696d\u52d9\u9700\u6c42\u8b8a\u66f4\uff1a\u96a8\u8457\u696d\u52d9\u7684\u767c\u5c55\uff0c\u539f\u6709\u5b57\u6bb5\u7684\u9577\u5ea6\u53ef\u80fd\u7121\u6cd5\u6eff\u8db3\u65b0\u7684\u9700\u6c42\u3002<\/li>\n<li>\u6578\u64da\u8cea\u91cf\u63d0\u5347\uff1a\u70ba\u4e86\u63d0\u9ad8\u6578\u64da\u7684\u6e96\u78ba\u6027\u548c\u4e00\u81f4\u6027\uff0c\u53ef\u80fd\u9700\u8981\u8abf\u6574\u5b57\u6bb5\u7684\u9577\u5ea6\u3002<\/li>\n<li>\u6027\u80fd\u512a\u5316\uff1a\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u9069\u7576\u7684\u5b57\u6bb5\u9577\u5ea6\u53ef\u4ee5\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%b8%8d%e5%90%8c%e6%95%b8%e6%93%9a%e5%ba%ab%e7%b3%bb%e7%b5%b1%e7%9a%84%e5%ad%97%e6%ae%b5%e9%95%b7%e5%ba%a6%e4%bf%ae%e6%94%b9%e6%96%b9%e6%b3%95-mcFxKvFkPQ\">\u4e0d\u540c\u6578\u64da\u5eab\u7cfb\u7d71\u7684\u5b57\u6bb5\u9577\u5ea6\u4fee\u6539\u65b9\u6cd5<\/h2>\n<h3 id=\"1-mysql-mcFxKvFkPQ\">1. MySQL<\/h3>\n<p>\u5728 MySQL \u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>ALTER TABLE<\/code> \u8a9e\u53e5\u4f86\u4fee\u6539\u5b57\u6bb5\u7684\u9577\u5ea6\u3002\u4ee5\u4e0b\u662f\u5177\u9ad4\u7684\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d MODIFY COLUMN \u5b57\u6bb5\u540d \u6578\u64da\u985e\u578b(\u65b0\u9577\u5ea6);<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5982\u679c\u8981\u5c07\u540d\u70ba <code>username<\/code> \u7684\u5b57\u6bb5\u9577\u5ea6\u5f9e 50 \u4fee\u6539\u70ba 100\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u547d\u4ee4\uff1a<\/p>\n<pre><code>ALTER TABLE users MODIFY COLUMN username VARCHAR(100);<\/code><\/pre>\n<h3 id=\"2-postgresql-mcFxKvFkPQ\">2. PostgreSQL<\/h3>\n<p>\u5728 PostgreSQL \u4e2d\uff0c\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\u7684\u8a9e\u6cd5\u8207 MySQL \u985e\u4f3c\uff0c\u540c\u6a23\u4f7f\u7528 <code>ALTER TABLE<\/code> \u8a9e\u53e5\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d ALTER COLUMN \u5b57\u6bb5\u540d TYPE \u6578\u64da\u985e\u578b(\u65b0\u9577\u5ea6);<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5c07 <code>email<\/code> \u5b57\u6bb5\u7684\u9577\u5ea6\u5f9e 255 \u4fee\u6539\u70ba 320\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u547d\u4ee4\uff1a<\/p>\n<pre><code>ALTER TABLE users ALTER COLUMN email TYPE VARCHAR(320);<\/code><\/pre>\n<h3 id=\"3-sql-server-mcFxKvFkPQ\">3. SQL Server<\/h3>\n<p>\u5728 SQL Server \u4e2d\uff0c\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\u7684\u8a9e\u6cd5\u4e5f\u4f7f\u7528 <code>ALTER TABLE<\/code> \u8a9e\u53e5\uff0c\u4f46\u9700\u8981\u4f7f\u7528 <code>ALTER COLUMN<\/code> \u4f86\u6307\u5b9a\u8981\u4fee\u6539\u7684\u5b57\u6bb5\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d ALTER COLUMN \u5b57\u6bb5\u540d \u6578\u64da\u985e\u578b(\u65b0\u9577\u5ea6);<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5c07 <code>description<\/code> \u5b57\u6bb5\u7684\u9577\u5ea6\u5f9e 500 \u4fee\u6539\u70ba 1000\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u547d\u4ee4\uff1a<\/p>\n<pre><code>ALTER TABLE products ALTER COLUMN description NVARCHAR(1000);<\/code><\/pre>\n<h3 id=\"4-oracle-mcFxKvFkPQ\">4. Oracle<\/h3>\n<p>\u5728 Oracle \u6578\u64da\u5eab\u4e2d\uff0c\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\u7684\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d MODIFY (\u5b57\u6bb5\u540d \u6578\u64da\u985e\u578b(\u65b0\u9577\u5ea6));<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5c07 <code>address<\/code> \u5b57\u6bb5\u7684\u9577\u5ea6\u5f9e 200 \u4fee\u6539\u70ba 300\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u547d\u4ee4\uff1a<\/p>\n<pre><code>ALTER TABLE customers MODIFY (address VARCHAR2(300));<\/code><\/pre>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-mcFxKvFkPQ\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\u6642\uff0c\u9700\u8981\u6ce8\u610f\u4ee5\u4e0b\u5e7e\u9ede\uff1a<\/p>\n<ul>\n<li>\u6578\u64da\u4e1f\u5931\u98a8\u96aa\uff1a\u5982\u679c\u5c07\u5b57\u6bb5\u9577\u5ea6\u7e2e\u77ed\uff0c\u53ef\u80fd\u6703\u5c0e\u81f4\u6578\u64da\u4e1f\u5931\uff0c\u56e0\u6b64\u5728\u9032\u884c\u6b64\u64cd\u4f5c\u524d\uff0c\u5efa\u8b70\u5099\u4efd\u6578\u64da\u3002<\/li>\n<li>\u5f71\u97ff\u6027\u80fd\uff1a\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\u53ef\u80fd\u6703\u5f71\u97ff\u6578\u64da\u5eab\u7684\u6027\u80fd\uff0c\u7279\u5225\u662f\u5728\u5927\u578b\u6578\u64da\u8868\u4e2d\u3002<\/li>\n<li>\u6aa2\u67e5\u7d04\u675f\uff1a\u5728\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\u4e4b\u524d\uff0c\u61c9\u6aa2\u67e5\u662f\u5426\u6709\u7d04\u675f\u689d\u4ef6\uff08\u5982\u5916\u9375\u3001\u7d22\u5f15\u7b49\uff09\u6703\u53d7\u5230\u5f71\u97ff\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-mcFxKvFkPQ\">\u7e3d\u7d50<\/h2>\n<p>\u4fee\u6539 SQL \u6578\u64da\u5eab\u5b57\u6bb5\u7684\u9577\u5ea6\u662f\u4e00\u9805\u5e38\u898b\u7684\u6578\u64da\u5eab\u7ba1\u7406\u4efb\u52d9\uff0c\u7121\u8ad6\u662f MySQL\u3001PostgreSQL\u3001SQL Server \u9084\u662f Oracle\uff0c\u90fd\u63d0\u4f9b\u4e86\u76f8\u61c9\u7684\u8a9e\u6cd5\u4f86\u5b8c\u6210\u9019\u4e00\u64cd\u4f5c\u3002\u5728\u9032\u884c\u4fee\u6539\u6642\uff0c\u52d9\u5fc5\u6ce8\u610f\u6578\u64da\u4e1f\u5931\u7684\u98a8\u96aa\u548c\u6027\u80fd\u5f71\u97ff\u3002\u5c0d\u65bc\u9700\u8981\u7a69\u5b9a\u548c\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u9078\u64c7\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u6216 <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u5e0c\u671b\u672c\u6587\u80fd\u5e6b\u52a9\u60a8\u66f4\u597d\u5730\u7406\u89e3\u548c\u64cd\u4f5c SQL \u6578\u64da\u5eab\u5b57\u6bb5\u7684\u9577\u5ea6\u4fee\u6539\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u5728 SQL \u6578\u64da\u5eab\u4e2d\u4fee\u6539\u5b57\u6bb5\u9577\u5ea6\uff0c\u638c\u63e1\u8a73\u7d30\u6b65\u9a5f\u548c\u6ce8\u610f\u4e8b\u9805\uff0c\u63d0\u5347\u6578\u64da\u7ba1\u7406\u6548\u7387\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-168385","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168385","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=168385"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168385\/revisions"}],"predecessor-version":[{"id":168386,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168385\/revisions\/168386"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=168385"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=168385"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=168385"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}