{"id":199929,"date":"2025-05-06T10:52:15","date_gmt":"2025-05-06T02:52:15","guid":{"rendered":"https:\/\/server.hk\/cnblog\/199929\/"},"modified":"2025-05-06T10:52:15","modified_gmt":"2025-05-06T02:52:15","slug":"%e6%b7%b1%e5%85%a5%e7%90%86%e8%a7%a3oracle%e4%b8%ad%e7%9a%84decode%e5%87%bd%e6%95%b0%e5%b9%b6%e9%99%84%e5%b8%a6%e7%a4%ba%e4%be%8b","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/199929\/","title":{"rendered":"\u6df1\u5165\u7406\u89e3Oracle\u4e2d\u7684DECODE\u51fd\u6570\u5e76\u9644\u5e26\u793a\u4f8b"},"content":{"rendered":"

<\/b> <\/p>\n

\u6df1\u5165\u7406\u89e3Oracle\u4e2d\u7684DECODE\u51fd\u6570\u5e76\u9644\u5e26\u793a\u4f8b<\/h1>\n

\u5c0f\u4f19\u4f34\u4eec\u5bf9\u6570\u636e\u5e93\u7f16\u7a0b\u611f\u5174\u8da3\u5417\uff1f\u662f\u5426\u6b63\u5728\u5b66\u4e60\u76f8\u5173\u77e5\u8bc6\u70b9\uff1f\u5982\u679c\u662f\uff0c\u90a3\u4e48\u672c\u6587\u300a\u6df1\u5165\u7406\u89e3Oracle\u4e2d\u7684DECODE\u51fd\u6570\u5e76\u9644\u5e26\u793a\u4f8b\u300b\uff0c\u5c31\u5f88\u9002\u5408\u4f60\uff0c\u672c\u7bc7\u6587\u7ae0\u8bb2\u89e3\u7684\u77e5\u8bc6\u70b9\u4e3b\u8981\u5305\u62ec\u3002\u5728\u4e4b\u540e\u7684\u6587\u7ae0\u4e2d\u4e5f\u4f1a\u591a\u591a\u5206\u4eab\u76f8\u5173\u77e5\u8bc6\u70b9\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u7684\u77e5\u8bc6\u79ef\u7d2f\u6709\u6240\u5e2e\u52a9\uff01<\/p>\n

Oracle\u4e2d\u7684DECODE\u51fd\u6570\u662f\u4e00\u79cd\u6761\u4ef6\u8868\u8fbe\u5f0f\uff0c\u5e38\u7528\u4e8e\u5728\u67e5\u8be2\u8bed\u53e5\u4e2d\u6839\u636e\u4e0d\u540c\u7684\u6761\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u7ed3\u679c\u3002\u672c\u6587\u5c06\u8be6\u7ec6\u4ecb\u7ecdDECODE\u51fd\u6570\u7684\u8bed\u6cd5\u3001\u7528\u6cd5\u548c\u793a\u4f8b\u4ee3\u7801\u3002<\/p>\n

\u4e00\u3001DECODE\u51fd\u6570\u8bed\u6cd5<\/h3>\n
DECODE(expr, search1, result1 [, search2, result2, ... , default])<\/pre>\n
    \n
  • expr<\/strong>\uff1a\u8981\u8fdb\u884c\u6bd4\u8f83\u7684\u8868\u8fbe\u5f0f\u6216\u5b57\u6bb5\u3002<\/li>\n
  • search1, search2, …<\/strong>\uff1a\u9700\u8981\u6bd4\u8f83\u7684\u503c\u3002<\/li>\n
  • result1, result2, …<\/strong>\uff1a\u5982\u679cexpr\u7b49\u4e8esearch1\u3001search2\u7b49\u5bf9\u5e94\u7684\u503c\uff0c\u5219\u8fd4\u56de\u5bf9\u5e94\u7684result1\u3001result2\u7b49\u3002<\/li>\n
  • default<\/strong>\uff1a\u5982\u679cexpr\u4e0d\u7b49\u4e8e\u4efb\u4f55search\u503c\uff0c\u5219\u8fd4\u56dedefault\u503c\u3002<\/li>\n<\/ul>\n
    \u4e8c\u3001DECODE\u51fd\u6570\u7528\u6cd5\u793a\u4f8b<\/h3>\n
    1. \u7b80\u5355\u793a\u4f8b\uff1a<\/h4>\n
    \u5047\u8bbe\u6709\u4e00\u4e2a\u540d\u4e3a\u201cemployees\u201d\u7684\u8868\uff0c\u5b57\u6bb5\u5305\u62ecemployee_id\u548cjob_id\uff0c\u73b0\u5728\u6211\u4eec\u60f3\u6839\u636e\u4e0d\u540c\u5458\u5de5\u7684\u5de5\u4f5cID\u6765\u7ed9\u51fa\u4e0d\u540c\u7684\u804c\u79f0\u3002\u793a\u4f8b\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
    SELECT employee_id, job_id, DECODE(job_id, 'IT_PROG', 'IT\u4e13\u5458', 'SA_MAN', '\u9500\u552e\u7ecf\u7406', 'OTHER') AS job_title\nFROM employees;<\/pre>\n
    \u4e0a\u8ff0\u4ee3\u7801\u4e2d\uff0c\u6839\u636e\u4e0d\u540c\u7684job_id\u8fd4\u56de\u4e0d\u540c\u7684\u804c\u79f0\uff0c\u201cIT_PROG\u201d\u8fd4\u56de\u201cIT\u4e13\u5458\u201d\uff0c\u201cSA_MAN\u201d\u8fd4\u56de\u201c\u9500\u552e\u7ecf\u7406\u201d\uff0c\u5176\u4ed6\u60c5\u51b5\u8fd4\u56de\u201cOTHER\u201d\u3002<\/p>\n
    2. \u591a\u6761\u4ef6\u793a\u4f8b\uff1a<\/h4>\n
    \u5982\u679c\u6211\u4eec\u60f3\u5728DECODE\u51fd\u6570\u4e2d\u5e94\u7528\u591a\u6761\u4ef6\u5224\u65ad\uff0c\u53ef\u4ee5\u50cf\u4e0b\u9762\u8fd9\u6837\u8fdb\u884c\uff1a<\/p>\n
    SELECT employee_id, job_id,\nDECODE(job_id,\n'SA_MAN', '\u9500\u552e\u7ecf\u7406',\n'IT_PROG', 'IT\u4e13\u5458',\n'MK_REP', '\u5e02\u573a\u4ee3\u8868',\n'AC_ACCOUNT', '\u4f1a\u8ba1',\n'OTHER') AS job_title\nFROM employees;<\/pre>\n
    \u5728\u8fd9\u4e2a\u793a\u4f8b\u4e2d\uff0c\u6839\u636e\u4e0d\u540c\u7684job_id\u8fd4\u56de\u76f8\u5e94\u7684\u804c\u79f0\u3002<\/p>\n
    3. \u4f7f\u7528\u9ed8\u8ba4\u503c\uff1a<\/h4>\n
    \u5982\u679cDECODE\u51fd\u6570\u7684expr\u4e0e\u6240\u6709\u7684search\u503c\u90fd\u4e0d\u5339\u914d\uff0c\u90a3\u4e48\u53ef\u4ee5\u8bbe\u7f6e\u4e00\u4e2a\u9ed8\u8ba4\u503c\u3002\u793a\u4f8b\u5982\u4e0b\uff1a<\/p>\n
    SELECT employee_id, job_id,\nDECODE(job_id,\n'SA_MAN', '\u9500\u552e\u7ecf\u7406',\n'IT_PROG', 'IT\u4e13\u5458',\nDEFAULT '\u5176\u4ed6\u804c\u4f4d') AS job_title\nFROM employees;<\/pre>\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u5982\u679cjob_id\u4e0d\u662f’SA_MAN’\u6216’IT_PROG’\uff0c\u5219\u8fd4\u56de\u9ed8\u8ba4\u503c\u201c\u5176\u4ed6\u804c\u4f4d\u201d\u3002<\/p>\n
    \u7ed3\u8bed<\/h3>\n
    \u901a\u8fc7\u4ee5\u4e0a\u793a\u4f8b\uff0c\u6211\u4eec\u53ef\u4ee5\u770b\u5230DECODE\u51fd\u6570\u5728Oracle\u6570\u636e\u5e93\u4e2d\u7684\u7075\u6d3b\u6027\u548c\u5b9e\u7528\u6027\u3002\u65e0\u8bba\u662f\u7b80\u5355\u7684\u6761\u4ef6\u5224\u65ad\u8fd8\u662f\u591a\u6761\u4ef6\u5224\u65ad\uff0cDECODE\u51fd\u6570\u90fd\u80fd\u5e2e\u52a9\u6211\u4eec\u6839\u636e\u4e0d\u540c\u7684\u6761\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u7ed3\u679c\uff0c\u63d0\u9ad8\u4e86SQL\u67e5\u8be2\u7684\u7075\u6d3b\u6027\u548c\u6548\u7387\u3002\u5e0c\u671b\u672c\u6587\u5bf9\u60a8\u7406\u89e3\u548c\u8fd0\u7528DECODE\u51fd\u6570\u6709\u6240\u5e2e\u52a9\u3002<\/p>\n
    \u4eca\u5929\u5173\u4e8e\u300a\u6df1\u5165\u7406\u89e3Oracle\u4e2d\u7684DECODE\u51fd\u6570\u5e76\u9644\u5e26\u793a\u4f8b\u300b\u7684\u5185\u5bb9\u4ecb\u7ecd\u5c31\u5230\u6b64\u7ed3\u675f\uff0c\u5982\u679c\u6709\u4ec0\u4e48\u7591\u95ee\u6216\u8005\u5efa\u8bae\uff0c\u53ef\u4ee5\u5728\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u4e0b\u591a\u591a\u56de\u590d\u4ea4\u6d41\uff1b\u6587\u4e2d\u82e5\u6709\u4e0d\u6b63\u4e4b\u5904\uff0c\u4e5f\u5e0c\u671b\u56de\u590d\u7559\u8a00\u4ee5\u544a\u77e5\uff01<\/p>\n
    \n
    \n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
    \u6df1\u5165\u7406\u89e3Oracle\u4e2d\u7684DECO...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-199929","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/199929","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=199929"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/199929\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=199929"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=199929"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=199929"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}