{"id":5621,"date":"2024-11-14T13:41:30","date_gmt":"2024-11-14T05:41:30","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5621\/"},"modified":"2024-11-14T13:41:30","modified_gmt":"2024-11-14T05:41:30","slug":"sql%e8%af%ad%e5%8f%a5%e6%80%8e%e4%b9%88%e4%bf%ae%e6%94%b9%e9%95%bf%e5%ba%a6","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5621\/","title":{"rendered":"sql\u8bed\u53e5\u600e\u4e48\u4fee\u6539\u957f\u5ea6"},"content":{"rendered":"

\n \u82e5\u8981\u4fee\u6539 sql \u8bed\u53e5\u4e2d\u5217\u7684\u957f\u5ea6\uff1a\u786e\u5b9a\u8981\u4fee\u6539\u7684\u5217\u548c\u6240\u9700\u957f\u5ea6\uff1b\u4f7f\u7528 alter table \u8bed\u53e5\u6307\u5b9a\u65b0\u6570\u636e\u7c7b\u578b\uff08\u5982\u6574\u6570\u3001\u5b57\u7b26\u4e32\uff09\u548c\u957f\u5ea6\uff1b\u6839\u636e\u6570\u636e\u7c7b\u578b\u8bbe\u7f6e\u957f\u5ea6\u5355\u4f4d\uff08\u5982\u5b57\u7b26\u6570\u3001\u4f4d\u6570\uff09\uff1b\u6267\u884c alter table \u8bed\u53e5\u5e94\u7528\u66f4\u6539\u3002\n<\/p><\/blockquote>\n

\"sql\u8bed\u53e5\u600e\u4e48\u4fee\u6539\u957f\u5ea6\u63d2\u56fe\"<\/p>\n

\u4fee\u6539 SQL \u8bed\u53e5\u4e2d\u5217\u957f\u5ea6\u7684\u6b65\u9aa4<\/strong><\/p>\n

1. \u786e\u5b9a\u9700\u8981\u4fee\u6539\u957f\u5ea6\u7684\u5217<\/strong><\/p>\n

\u786e\u5b9a\u60f3\u8981\u4fee\u6539\u6570\u636e\u7c7b\u578b\u548c\u957f\u5ea6\u7684\u5217\u3002<\/p>\n

2. \u4f7f\u7528 ALTER TABLE \u8bed\u53e5<\/strong><\/p>\n

\u4f7f\u7528 ALTER TABLE \u8bed\u53e5\u4fee\u6539\u5217\uff0c\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n

ALTER TABLE table_name ALTER COLUMN column_name data_type(new_length);<\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
\u5176\u4e2d\uff1a<\/p>\n
    \n
  • table_name \u662f\u8981\u4fee\u6539\u7684\u8868\u540d\u3002<\/li>\n
  • column_name \u662f\u8981\u4fee\u6539\u957f\u5ea6\u7684\u5217\u540d\u3002<\/li>\n
  • data_type \u662f\u65b0\u7684\u6570\u636e\u7c7b\u578b\u3002<\/li>\n
  • new_length \u662f\u65b0\u5217\u957f\u5ea6\u3002<\/li>\n<\/ul>\n
    3. \u6307\u5b9a\u65b0\u7684\u6570\u636e\u7c7b\u578b<\/strong><\/p>\n
    \u5217\u7684\u6570\u636e\u7c7b\u578b\u53ef\u4ee5\u662f\u4ee5\u4e0b\u51e0\u79cd\u7c7b\u578b\u4e4b\u4e00\uff1a<\/p>\n
      \n
    • \u6574\u6570\uff1aINT\u3001SMALLINT\u3001BIGINT<\/li>\n
    • \u6d6e\u70b9\u6570\uff1aFLOAT\u3001DOUBLE<\/li>\n
    • \u5b57\u7b26\u4e32\uff1aVARCHAR\u3001CHAR<\/li>\n
    • \u65e5\u671f\u548c\u65f6\u95f4\uff1aDATE\u3001TIME\u3001DATETIME<\/li>\n<\/ul>\n
      4. \u6307\u5b9a\u65b0\u957f\u5ea6<\/strong><\/p>\n
      \u5217\u957f\u5ea6\u7684\u5355\u4f4d\u53d6\u51b3\u4e8e\u6570\u636e\u7c7b\u578b\u3002\u4f8b\u5982\uff0c\u5bf9\u4e8e\u5b57\u7b26\u4e32\u7c7b\u578b\uff0c\u957f\u5ea6\u8868\u793a\u5b57\u7b26\u6570\uff1b\u5bf9\u4e8e\u6574\u6570\u7c7b\u578b\uff0c\u957f\u5ea6\u8868\u793a\u4f4d\u6570\u3002<\/p>\n
      5. \u6267\u884c ALTER TABLE \u8bed\u53e5<\/strong><\/p>\n
      \u6267\u884c ALTER TABLE \u8bed\u53e5\u4ee5\u5e94\u7528\u66f4\u6539\u3002<\/p>\n
      \u793a\u4f8b\uff1a<\/strong><\/p>\n
      \u8981\u5c06 users \u8868\u4e2d\u7684 name \u5217\u7684\u957f\u5ea6\u4ece 255 \u4e2a\u5b57\u7b26\u589e\u52a0\u5230 500 \u4e2a\u5b57\u7b26\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u8bed\u53e5\uff1a<\/p>\n
      ALTER TABLE users ALTER COLUMN name VARCHAR(500);<\/pre>\n
       \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
      \u6ce8\u610f\u4e8b\u9879\uff1a<\/strong><\/p>\n
        \n
      • \u5982\u679c\u5217\u5305\u542b\u73b0\u6709\u6570\u636e\uff0c\u5219\u5fc5\u987b\u786e\u4fdd\u65b0\u957f\u5ea6\u8db3\u591f\u5bb9\u7eb3\u6240\u6709\u6570\u636e\u3002<\/li>\n
      • \u5bf9\u4e8e\u67d0\u4e9b\u6570\u636e\u7c7b\u578b\uff0c\u53ef\u80fd\u8fd8\u6709\u5176\u4ed6\u9650\u5236\uff0c\u4f8b\u5982\u5c0f\u6570\u70b9\u548c\u5c0f\u6570\u4f4d\u6570\u3002<\/li>\n
      • \u5728\u4fee\u6539\u5217\u957f\u5ea6\u4e4b\u524d\uff0c\u8bf7\u786e\u4fdd\u5907\u4efd\u6570\u636e\u5e93\u3002<\/li>\n<\/ul>\n
        \u4ee5\u4e0a\u5c31\u662f\u600e\u4e48\u4fee\u6539\u957f\u5ea6\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
        \u82e5\u8981\u4fee\u6539 sql \u8bed\u53e5\u4e2d\u5217\u7684\u957f\u5ea6\uff1a\u786e\u5b9a\u8981\u4fee\u6539\u7684\u5217\u548c\u6240\u9700\u957f\u5ea6\uff1b\u4f7f\u7528 alter table \u8bed\u53e5\u6307\u5b9a\u65b0\u6570\u636e\u7c7b\u578b\uff08\u5982\u6574\u6570\u3001\u5b57\u7b26\u4e32\uff09\u548c\u957f\u5ea6\uff1b\u6839\u636e\u6570\u636e\u7c7b\u578b\u8bbe\u7f6e\u957f\u5ea6\u5355\u4f4d\uff08\u5982\u5b57\u7b26\u6570\u3001\u4f4d\u6570\uff09\uff1b\u6267\u884c alter table \u8bed\u53e5\u5e94\u7528\u66f4\u6539\u3002 \u4fee\u6539 SQL \u8bed\u53e5\u4e2d\u5217\u957f\u5ea6\u7684\u6b65\u9aa4 1. \u786e\u5b9a\u9700\u8981\u4fee\u6539\u957f\u5ea6\u7684\u5217 \u786e\u5b9a\u60f3\u8981\u4fee\u6539\u6570\u636e\u7c7b\u578b\u548c\u957f\u5ea6\u7684\u5217\u3002 2. \u4f7f\u7528 ALTER TABLE \u8bed\u53e5 \u4f7f\u7528 ALTER TABLE \u8bed\u53e5\u4fee\u6539\u5217\uff0c\u8bed\u6cd5\u5982\u4e0b\uff1a ALTER TABLE table_name ALTER COLUMN column_name data_type(new_length); \u767b\u5f55\u540e\u590d\u5236 \u5176\u4e2d\uff1a table_name \u662f\u8981\u4fee\u6539\u7684\u8868\u540d\u3002 column_name \u662f\u8981\u4fee\u6539\u957f\u5ea6\u7684\u5217\u540d\u3002 data_type \u662f\u65b0\u7684\u6570\u636e\u7c7b\u578b\u3002 new_length \u662f\u65b0\u5217\u957f\u5ea6\u3002 3. \u6307\u5b9a\u65b0\u7684\u6570\u636e\u7c7b\u578b \u5217\u7684\u6570\u636e\u7c7b\u578b\u53ef\u4ee5\u662f\u4ee5\u4e0b\u51e0\u79cd\u7c7b\u578b\u4e4b\u4e00\uff1a \u6574\u6570\uff1aINT\u3001SMALLINT\u3001BIGINT \u6d6e\u70b9\u6570\uff1aFLOAT\u3001DOUBLE \u5b57\u7b26\u4e32\uff1aVARCHAR\u3001CHAR \u65e5\u671f\u548c\u65f6\u95f4\uff1aDATE\u3001TIME\u3001DATETIME 4. \u6307\u5b9a\u65b0\u957f\u5ea6 \u5217\u957f\u5ea6\u7684\u5355\u4f4d\u53d6\u51b3\u4e8e\u6570\u636e\u7c7b\u578b\u3002\u4f8b\u5982\uff0c\u5bf9\u4e8e\u5b57\u7b26\u4e32\u7c7b\u578b\uff0c\u957f\u5ea6\u8868\u793a\u5b57\u7b26\u6570\uff1b\u5bf9\u4e8e\u6574\u6570\u7c7b\u578b\uff0c\u957f\u5ea6\u8868\u793a\u4f4d\u6570\u3002 5. \u6267\u884c ALTER TABLE […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-5621","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5621","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=5621"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5621\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5621"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5621"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5621"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}