{"id":5241,"date":"2024-11-14T08:52:24","date_gmt":"2024-11-14T00:52:24","guid":{"rendered":"https:\/\/fwq.ai\/blog\/5241\/"},"modified":"2024-11-14T08:52:24","modified_gmt":"2024-11-14T00:52:24","slug":"mysql%e5%88%a4%e6%96%ad%e8%af%ad%e5%8f%a5%e6%80%8e%e4%b9%88%e5%86%99","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/5241\/","title":{"rendered":"mysql\u5224\u65ad\u8bed\u53e5\u600e\u4e48\u5199"},"content":{"rendered":"

\n mysql \u4e2d\u7528\u4e8e\u5224\u65ad\u8bed\u53e5\u6709\uff1aif \u51fd\u6570\uff0c\u6839\u636e\u6761\u4ef6\u8fd4\u56de\u4e0d\u540c\u503c\uff0c\u8bed\u6cd5\uff1aif(condition, true_value, false_value)\uff1bcase \u8bed\u53e5\uff0c\u6839\u636e\u591a\u4e2a\u6761\u4ef6\u8fd4\u56de\u4e0d\u540c\u503c\uff0c\u8bed\u6cd5\uff1acase when condition then result else default_result end\u3002\n<\/p><\/blockquote>\n

\"mysql\u5224\u65ad\u8bed\u53e5\u600e\u4e48\u5199\u63d2\u56fe\"<\/p>\n

MySQL \u5224\u65ad\u8bed\u53e5<\/strong><\/p>\n

1. IF \u51fd\u6570<\/strong><\/p>\n

IF \u51fd\u6570\u7528\u4e8e\u6839\u636e\u4e00\u4e2a\u6761\u4ef6\u6765\u8fd4\u56de\u4e0d\u540c\u7684\u503c\u3002\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n

IF(condition, true_value, false_value)<\/pre>\n
 \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
    \n
  • condition\uff1a\u8981\u5224\u65ad\u7684\u6761\u4ef6\u3002<\/li>\n
  • true_value\uff1a\u5982\u679c\u6761\u4ef6\u4e3a\u771f\uff0c\u5219\u8fd4\u56de\u7684\u503c\u3002<\/li>\n
  • false_value\uff1a\u5982\u679c\u6761\u4ef6\u4e3a\u5047\uff0c\u5219\u8fd4\u56de\u7684\u503c\u3002<\/li>\n<\/ul>\n
    2. CASE \u8bed\u53e5<\/strong><\/p>\n
    CASE \u8bed\u53e5\u7528\u4e8e\u6839\u636e\u591a\u4e2a\u6761\u4ef6\u6765\u8fd4\u56de\u4e0d\u540c\u7684\u503c\u3002\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n
    CASE\n  WHEN condition1 THEN result1\n  WHEN condition2 THEN result2\n  ...\n  ELSE default_result\nEND<\/pre>\n
     \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
      \n
    • condition1, condition2, …\uff1a\u8981\u5224\u65ad\u7684\u6761\u4ef6\u3002<\/li>\n
    • result1, result2, …\uff1a\u5982\u679c\u6761\u4ef6\u4e3a\u771f\uff0c\u5219\u8fd4\u56de\u7684\u503c\u3002<\/li>\n
    • default_result\uff1a\u5982\u679c\u6ca1\u6709\u6761\u4ef6\u5339\u914d\uff0c\u5219\u8fd4\u56de\u7684\u503c\u3002<\/li>\n<\/ul>\n
      \u793a\u4f8b<\/strong><\/p>\n
      \u5224\u65ad\u4e00\u4e2a\u6570\u5b57\u662f\u5426\u5927\u4e8e 10\uff1a<\/p>\n
      IF(number > 10, '\u5927\u4e8e 10', '\u5c0f\u4e8e\u6216\u7b49\u4e8e 10')<\/pre>\n
       \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
      \u4f7f\u7528 CASE \u8bed\u53e5\u6839\u636e\u6210\u7ee9\u5c06\u5b66\u751f\u5206\u4e3a\u4e0d\u540c\u7684\u7b49\u7ea7\uff1a<\/p>\n
      CASE\n  WHEN grade >= 90 THEN '\u4f18'\n  WHEN grade >= 80 THEN '\u826f'\n  WHEN grade >= 70 THEN '\u4e2d'\n  ELSE '\u5dee'\nEND<\/pre>\n
       \u767b\u5f55\u540e\u590d\u5236 <\/p>\n
      \u4ee5\u4e0a\u5c31\u662f\u5224\u65ad\u8bed\u53e5\u600e\u4e48\u5199\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":"
      mysql \u4e2d\u7528\u4e8e\u5224\u65ad\u8bed\u53e5\u6709\uff1aif \u51fd\u6570\uff0c\u6839\u636e\u6761\u4ef6\u8fd4\u56de\u4e0d\u540c\u503c\uff0c\u8bed\u6cd5\uff1aif(condition, true_value, false_value)\uff1bcase \u8bed\u53e5\uff0c\u6839\u636e\u591a\u4e2a\u6761\u4ef6\u8fd4\u56de\u4e0d\u540c\u503c\uff0c\u8bed\u6cd5\uff1acase when condition then result else default_result end\u3002 MySQL \u5224\u65ad\u8bed\u53e5 1. IF \u51fd\u6570 IF \u51fd\u6570\u7528\u4e8e\u6839\u636e\u4e00\u4e2a\u6761\u4ef6\u6765\u8fd4\u56de\u4e0d\u540c\u7684\u503c\u3002\u8bed\u6cd5\u5982\u4e0b\uff1a IF(condition, true_value, false_value) \u767b\u5f55\u540e\u590d\u5236 condition\uff1a\u8981\u5224\u65ad\u7684\u6761\u4ef6\u3002 true_value\uff1a\u5982\u679c\u6761\u4ef6\u4e3a\u771f\uff0c\u5219\u8fd4\u56de\u7684\u503c\u3002 false_value\uff1a\u5982\u679c\u6761\u4ef6\u4e3a\u5047\uff0c\u5219\u8fd4\u56de\u7684\u503c\u3002 2. CASE \u8bed\u53e5 CASE \u8bed\u53e5\u7528\u4e8e\u6839\u636e\u591a\u4e2a\u6761\u4ef6\u6765\u8fd4\u56de\u4e0d\u540c\u7684\u503c\u3002\u8bed\u6cd5\u5982\u4e0b\uff1a CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 … ELSE default_result END \u767b\u5f55\u540e\u590d\u5236 condition1, condition2, …\uff1a\u8981\u5224\u65ad\u7684\u6761\u4ef6\u3002 result1, result2, …\uff1a\u5982\u679c\u6761\u4ef6\u4e3a\u771f\uff0c\u5219\u8fd4\u56de\u7684\u503c\u3002 default_result\uff1a\u5982\u679c\u6ca1\u6709\u6761\u4ef6\u5339\u914d\uff0c\u5219\u8fd4\u56de\u7684\u503c\u3002 \u793a\u4f8b \u5224\u65ad\u4e00\u4e2a\u6570\u5b57\u662f\u5426\u5927\u4e8e […]<\/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-5241","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5241","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=5241"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/5241\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=5241"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=5241"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=5241"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}