{"id":5659,"date":"2024-11-14T12:36:44","date_gmt":"2024-11-14T04:36:44","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5659\/"},"modified":"2024-11-14T12:36:44","modified_gmt":"2024-11-14T04:36:44","slug":"sql%e6%95%b0%e6%8d%ae%e7%b1%bb%e5%9e%8b%e6%80%8e%e4%b9%88%e6%94%b9","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5659\/","title":{"rendered":"sql\u6570\u636e\u7c7b\u578b\u600e\u4e48\u6539"},"content":{"rendered":"

\n sql \u4e2d\u66f4\u6539\u6570\u636e\u7c7b\u578b\u7684\u6b65\u9aa4\uff1a1. \u786e\u5b9a\u9700\u8981\u66f4\u6539\u7c7b\u578b\u7684\u5217\uff1b2. \u4f7f\u7528 alter table \u8bed\u53e5\u66f4\u6539\u7c7b\u578b\uff0c\u6307\u5b9a\u65b0\u6570\u636e\u7c7b\u578b\uff1b3. \u5904\u7406\u6570\u636e\u8f6c\u6362\uff1b4. \u5904\u7406\u5916\u952e\u5173\u7cfb\uff1b5. \u63d0\u4ea4\u66f4\u6539\u3002\n<\/p><\/blockquote>\n

\"sql\u6570\u636e\u7c7b\u578b\u600e\u4e48\u6539\u63d2\u56fe\"<\/p>\n

\u5982\u4f55\u66f4\u6539 SQL \u6570\u636e\u7c7b\u578b<\/strong><\/p>\n

\u5728 SQL \u4e2d\u66f4\u6539\u6570\u636e\u7c7b\u578b\u7684\u6b65\u9aa4\u5982\u4e0b\uff1a<\/p>\n

1. \u786e\u5b9a\u9700\u8981\u66f4\u6539\u7c7b\u578b\u7684\u5217<\/strong><\/p>\n

\u786e\u5b9a\u9700\u8981\u66f4\u6539\u6570\u636e\u7c7b\u578b\u7684\u8868\u548c\u5217\u3002<\/p>\n

2. \u4f7f\u7528 ALTER TABLE \u8bed\u53e5\u66f4\u6539\u7c7b\u578b<\/strong><\/p>\n

\u4f7f\u7528\u4ee5\u4e0b\u8bed\u6cd5\uff1a<\/p>\n

ALTER TABLE table_name\nALTER COLUMN column_name NEW_DATA_TYPE;<\/pre>\n
  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n
\u4f8b\u5982\uff0c\u8981\u5c06\u8868 customers \u4e2d\u7684\u5217 age \u4ece INTEGER \u66f4\u6539\u4e3a VARCHAR(10)\uff1a<\/p>\n
ALTER TABLE customers\nALTER COLUMN age VARCHAR(10);<\/pre>\n
  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n
3. \u6307\u5b9a\u65b0\u6570\u636e\u7c7b\u578b<\/strong><\/p>\n
\u6307\u5b9a\u65b0\u6570\u636e\u7c7b\u578b\u3002\u53ef\u7528\u6570\u636e\u7c7b\u578b\u56e0\u6570\u636e\u5e93\u7cfb\u7edf\u800c\u5f02\uff0c\u4f46\u5e38\u89c1\u7c7b\u578b\u5305\u62ec\uff1a<\/p>\n
    \n
  • \u6574\u6570 (INT, SMALLINT)<\/li>\n
  • \u6d6e\u70b9 (FLOAT, DOUBLE)<\/li>\n
  • \u5b57\u7b26\u4e32 (VARCHAR, CHAR)<\/li>\n
  • \u65e5\u671f\u548c\u65f6\u95f4 (DATE, TIME, TIMESTAMP)<\/li>\n<\/ul>\n
    4. \u5904\u7406\u6570\u636e\u8f6c\u6362<\/strong><\/p>\n
    \u5982\u679c\u65b0\u6570\u636e\u7c7b\u578b\u4e0e\u65e7\u6570\u636e\u7c7b\u578b\u4e0d\u540c\uff0cSQL \u5c06\u5c1d\u8bd5\u8f6c\u6362\u6570\u636e\u3002\u8fd9\u53ef\u80fd\u9700\u8981\u5f3a\u5236\u8f6c\u6362\u6216\u6570\u636e\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5982\u679c\u5c06 INTEGER \u66f4\u6539\u4e3a VARCHAR(10)\uff0c\u5219\u8f83\u5927\u7684\u6574\u6570\u53ef\u80fd\u88ab\u622a\u65ad\u3002<\/p>\n
    5. \u63d0\u4ea4\u66f4\u6539<\/strong><\/p>\n
    \u6210\u529f\u66f4\u6539\u6570\u636e\u7c7b\u578b\u540e\uff0c\u52a1\u5fc5\u63d0\u4ea4\u66f4\u6539\u4ee5\u4f7f\u5b83\u4eec\u6c38\u4e45\u751f\u6548\u3002<\/p>\n
    \u6ce8\u610f\u4e8b\u9879\uff1a<\/strong><\/p>\n
      \n
    • \u66f4\u6539\u6570\u636e\u7c7b\u578b\u53ef\u80fd\u4f1a\u5f71\u54cd\u6570\u636e\u5e93\u6027\u80fd\u548c\u5b58\u50a8\u3002<\/li>\n
    • \u66f4\u6539\u6570\u636e\u7c7b\u578b\u53ef\u80fd\u5bf9\u5f15\u7528\u8be5\u5217\u7684\u5176\u4ed6\u8868\u7684\u5916\u952e\u5173\u7cfb\u4ea7\u751f\u5f71\u54cd\u3002<\/li>\n
    • \u5728\u66f4\u6539\u6570\u636e\u7c7b\u578b\u4e4b\u524d\uff0c\u8bf7\u52a1\u5fc5\u5907\u4efd\u6570\u636e\u5e93\u3002<\/li>\n<\/ul>\n
      \u4ee5\u4e0a\u5c31\u662fsql\u6570\u636e\u7c7b\u578b\u600e\u4e48\u6539\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":"
      sql \u4e2d\u66f4\u6539\u6570\u636e\u7c7b\u578b\u7684\u6b65\u9aa4\uff1a1. \u786e\u5b9a\u9700\u8981\u66f4\u6539\u7c7b\u578b\u7684\u5217\uff1b2. \u4f7f\u7528 alter table \u8bed\u53e5\u66f4\u6539\u7c7b\u578b\uff0c\u6307\u5b9a\u65b0\u6570\u636e\u7c7b\u578b\uff1b3. \u5904\u7406\u6570\u636e\u8f6c\u6362\uff1b4. \u5904\u7406\u5916\u952e\u5173\u7cfb\uff1b5. \u63d0\u4ea4\u66f4\u6539\u3002 \u5982\u4f55\u66f4\u6539 SQL \u6570\u636e\u7c7b\u578b \u5728 SQL \u4e2d\u66f4\u6539\u6570\u636e\u7c7b\u578b\u7684\u6b65\u9aa4\u5982\u4e0b\uff1a 1. \u786e\u5b9a\u9700\u8981\u66f4\u6539\u7c7b\u578b\u7684\u5217 \u786e\u5b9a\u9700\u8981\u66f4\u6539\u6570\u636e\u7c7b\u578b\u7684\u8868\u548c\u5217\u3002 2. \u4f7f\u7528 ALTER TABLE \u8bed\u53e5\u66f4\u6539\u7c7b\u578b \u4f7f\u7528\u4ee5\u4e0b\u8bed\u6cd5\uff1a ALTER TABLE table_name ALTER COLUMN column_name NEW_DATA_TYPE; \u767b\u5f55\u540e\u590d\u5236 \u4f8b\u5982\uff0c\u8981\u5c06\u8868 customers \u4e2d\u7684\u5217 age \u4ece INTEGER \u66f4\u6539\u4e3a VARCHAR(10)\uff1a ALTER TABLE customers ALTER COLUMN age VARCHAR(10); \u767b\u5f55\u540e\u590d\u5236 3. \u6307\u5b9a\u65b0\u6570\u636e\u7c7b\u578b \u6307\u5b9a\u65b0\u6570\u636e\u7c7b\u578b\u3002\u53ef\u7528\u6570\u636e\u7c7b\u578b\u56e0\u6570\u636e\u5e93\u7cfb\u7edf\u800c\u5f02\uff0c\u4f46\u5e38\u89c1\u7c7b\u578b\u5305\u62ec\uff1a \u6574\u6570 (INT, SMALLINT) […]<\/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-5659","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5659","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=5659"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5659\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5659"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5659"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5659"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}