{"id":5956,"date":"2024-11-14T08:05:32","date_gmt":"2024-11-14T00:05:32","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5956\/"},"modified":"2024-11-14T08:05:32","modified_gmt":"2024-11-14T00:05:32","slug":"sql%e5%a6%82%e4%bd%95%e5%86%99%e5%be%aa%e7%8e%af%e8%af%ad%e5%8f%a5","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5956\/","title":{"rendered":"sql\u5982\u4f55\u5199\u5faa\u73af\u8bed\u53e5"},"content":{"rendered":"

\n sql \u4e2d\u6ca1\u6709\u4f20\u7edf\u7684\u5faa\u73af\u8bed\u53e5\uff0c\u4f46\u53ef\u4f7f\u7528\u9012\u5f52 cte \u6a21\u62df\u5faa\u73af\uff1a\u521b\u5efa\u9012\u5f52 cte\uff0c\u5305\u542b”iteration”\u5217\u6765\u8ddf\u8e2a\u5faa\u73af\u6b21\u6570\u3002\u9012\u5f52\u67e5\u8be2\u66f4\u65b0”iteration”\u5217\u5e76\u6ee1\u8db3\u5faa\u73af\u6761\u4ef6\u3002\u4f7f\u7528 select \u8bed\u53e5\u4ece cte \u4e2d\u9009\u62e9\u6240\u9700\u6570\u636e\u3002\n<\/p><\/blockquote>\n

\"sql\u5982\u4f55\u5199\u5faa\u73af\u8bed\u53e5\u63d2\u56fe\"<\/p>\n

SQL \u4e2d\u7684\u5faa\u73af\u8bed\u53e5<\/strong><\/p>\n

SQL \u4e2d\u6ca1\u6709\u4f20\u7edf\u7684\u5faa\u73af\u8bed\u53e5\uff0c\u5982 while() \u6216 for()\u3002\u4f46\u662f\uff0c\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528\u9012\u5f52\u7684\u516c\u5171\u8868\u8868\u8fbe\u5f0f (CTE) \u6765\u6a21\u62df\u5faa\u73af\u8bed\u53e5\u3002<\/p>\n

\u4f7f\u7528 CTE \u7f16\u5199\u5faa\u73af\u8bed\u53e5<\/strong><\/p>\n

\u8981\u4f7f\u7528 CTE \u7f16\u5199\u5faa\u73af\u8bed\u53e5\uff0c\u9700\u8981\u4ee5\u4e0b\u6b65\u9aa4\uff1a<\/p>\n

    \n
  1. \u521b\u5efa\u9012\u5f52 CTE\uff1a<\/strong>\u521b\u5efa\u4e00\u4e2a CTE\uff0c\u5305\u542b\u4e00\u4e2a\u540d\u4e3a “iteration” \u7684\u5217\u6765\u8ddf\u8e2a\u5faa\u73af\u6b21\u6570\u3002<\/li>\n
  2. \u9012\u5f52\u67e5\u8be2\uff1a<\/strong>\u5728 CTE \u4e2d\u7f16\u5199\u9012\u5f52\u67e5\u8be2\uff0c\u8be5\u67e5\u8be2\u5c06\u66f4\u65b0 “iteration” \u5217\u5e76\u6ee1\u8db3\u6240\u9700\u7684\u5faa\u73af\u6761\u4ef6\u3002<\/li>\n
  3. \u5f15\u7528 CTE\uff1a<\/strong>\u4f7f\u7528\u4e00\u4e2a SELECT \u8bed\u53e5\u4ece CTE \u4e2d\u9009\u62e9\u6240\u9700\u7684\u6570\u636e\u3002<\/li>\n<\/ol>\n

    \u793a\u4f8b\uff1a<\/strong><\/p>\n

    \u5047\u8bbe\u6211\u4eec\u60f3\u8981\u521b\u5efa\u4e00\u4e2a\u5faa\u73af\uff0c\u6253\u5370\u6570\u5b57 1 \u5230 10\uff1a<\/p>\n

    WITH RECURSIVE numbers AS (\n  SELECT 1 AS iteration\n  UNION ALL\n  SELECT iteration + 1\n  FROM numbers\n  WHERE iteration < 10\n)\n\nSELECT iteration\nFROM numbers;<\/pre>\n
      \u767b\u5f55\u540e\u590d\u5236   <\/p>\n
    \u6267\u884c\u6b65\u9aa4\uff1a<\/strong><\/p>\n
      \n
    1. \u521b\u5efa\u540d\u4e3a “numbers” \u7684 CTE\uff0c\u521d\u59cb “iteration” \u503c\u4e3a 1\u3002<\/li>\n
    2. \u4f7f\u7528\u9012\u5f52\u67e5\u8be2\u66f4\u65b0 “iteration” \u5217\u5e76\u68c0\u67e5\u5faa\u73af\u6761\u4ef6 (iteration <\/li>\n
    3. \u4f7f\u7528 SELECT \u8bed\u53e5\u4ece CTE \u4e2d\u9009\u62e9 “iteration” \u5217\u3002<\/li>\n<\/ol>\n
      \u7ed3\u679c\u5c06\u662f\u4e00\u4e2a\u8868\uff0c\u5176\u4e2d\u5305\u542b\u4ece 1 \u5230 10 \u7684\u6570\u5b57\u3002<\/p>\n
      \u4ee5\u4e0a\u5c31\u662fsql\u5982\u4f55\u5199\u5faa\u73af\u8bed\u53e5\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\u6ca1\u6709\u4f20\u7edf\u7684\u5faa\u73af\u8bed\u53e5\uff0c\u4f46\u53ef\u4f7f\u7528\u9012\u5f52 cte \u6a21\u62df\u5faa\u73af\uff1a\u521b\u5efa\u9012\u5f52 cte\uff0c\u5305\u542b”iteration”\u5217\u6765\u8ddf\u8e2a\u5faa\u73af\u6b21\u6570\u3002\u9012\u5f52\u67e5\u8be2\u66f4\u65b0”iteration”\u5217\u5e76\u6ee1\u8db3\u5faa\u73af\u6761\u4ef6\u3002\u4f7f\u7528 select \u8bed\u53e5\u4ece cte \u4e2d\u9009\u62e9\u6240\u9700\u6570\u636e\u3002 SQL \u4e2d\u7684\u5faa\u73af\u8bed\u53e5 SQL \u4e2d\u6ca1\u6709\u4f20\u7edf\u7684\u5faa\u73af\u8bed\u53e5\uff0c\u5982 while() \u6216 for()\u3002\u4f46\u662f\uff0c\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528\u9012\u5f52\u7684\u516c\u5171\u8868\u8868\u8fbe\u5f0f (CTE) \u6765\u6a21\u62df\u5faa\u73af\u8bed\u53e5\u3002 \u4f7f\u7528 CTE \u7f16\u5199\u5faa\u73af\u8bed\u53e5 \u8981\u4f7f\u7528 CTE \u7f16\u5199\u5faa\u73af\u8bed\u53e5\uff0c\u9700\u8981\u4ee5\u4e0b\u6b65\u9aa4\uff1a \u521b\u5efa\u9012\u5f52 CTE\uff1a\u521b\u5efa\u4e00\u4e2a CTE\uff0c\u5305\u542b\u4e00\u4e2a\u540d\u4e3a “iteration” \u7684\u5217\u6765\u8ddf\u8e2a\u5faa\u73af\u6b21\u6570\u3002 \u9012\u5f52\u67e5\u8be2\uff1a\u5728 CTE \u4e2d\u7f16\u5199\u9012\u5f52\u67e5\u8be2\uff0c\u8be5\u67e5\u8be2\u5c06\u66f4\u65b0 “iteration” \u5217\u5e76\u6ee1\u8db3\u6240\u9700\u7684\u5faa\u73af\u6761\u4ef6\u3002 \u5f15\u7528 CTE\uff1a\u4f7f\u7528\u4e00\u4e2a SELECT \u8bed\u53e5\u4ece CTE \u4e2d\u9009\u62e9\u6240\u9700\u7684\u6570\u636e\u3002 \u793a\u4f8b\uff1a \u5047\u8bbe\u6211\u4eec\u60f3\u8981\u521b\u5efa\u4e00\u4e2a\u5faa\u73af\uff0c\u6253\u5370\u6570\u5b57 1 \u5230 10\uff1a WITH RECURSIVE numbers AS ( SELECT 1 AS iteration UNION […]<\/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-5956","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5956","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=5956"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5956\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5956"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5956"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5956"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}