{"id":193287,"date":"2020-11-14T16:19:06","date_gmt":"2020-11-14T08:19:06","guid":{"rendered":"http:\/\/4563.org\/?p=193287"},"modified":"2020-11-14T16:19:06","modified_gmt":"2020-11-14T08:19:06","slug":"%e5%8f%91%e7%8e%b0%e5%a4%9a%e7%a7%8d%e6%95%b0%e6%8d%ae%e5%ba%93-group-by-%e5%af%b9%e5%ad%97%e7%ac%a6%e4%b8%b2%e9%a6%96%e5%b0%be%e7%a9%ba%e6%a0%bc%e7%9a%84%e5%9d%91%e6%ad%bb%e4%ba%ba%e4%b8%8d%e5%81%bf","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=193287","title":{"rendered":"\u53d1\u73b0\u591a\u79cd\u6570\u636e\u5e93 group by \u5bf9\u5b57\u7b26\u4e32\u9996\u5c3e\u7a7a\u683c\u7684\u5751\u6b7b\u4eba\u4e0d\u507f\u547d\u89c4\u8303"},"content":{"rendered":"
\n
\n
\n

\u53d1\u73b0\u591a\u79cd\u6570\u636e\u5e93 group by \u5bf9\u5b57\u7b26\u4e32\u9996\u5c3e\u7a7a\u683c\u7684\u5751\u6b7b\u4eba\u4e0d\u507f\u547d\u89c4\u8303 <\/h1>\n

<\/p>\n

\n
\u8cc7\u6df1\u5927\u4f6c : xiangyuecn <\/span> <\/i> 0<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n

rt \u5df2\u6d4b\u8bd5 mysql sqlserver<\/p>\n

“\u5b57\u7b26\u4e32” “\u5b57\u7b26\u4e32 ” \u4f1a\u5206\u5230\u540c\u4e00\u7ec4<\/p>\n

“\u5b57\u7b26\u4e32” ” \u5b57\u7b26\u4e32” \u53c8\u4e0d\u4f1a\u5206\u5230\u540c\u4e00\u7ec4<\/p>\n

\u8fd9\u79cd\u9ed8\u8ba4\u64cd\u4f5c\u7ad9\u5728\u5b57\u7b26\u6570\u636e\u5b58\u50a8\u7684\u89d2\u5ea6\uff0c\u548c\u9ed8\u8ba4\u4e0d\u533a\u5206\u5927\u5c0f\u5199\u4e00\u6837\u611a\u8822\u81f3\u6781\uff0c\u672c\u4eba\u89c2\u70b9\u3002<\/p>\n<\/p><\/div>\n

\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (19<\/span>) <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : lxk11153 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u8fd8\u6709\u8fd9\u4e2a feature [doge] <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : xiangyuecn <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u90fd\u662f\u7a7a\uff0c\u8868\u73b0\u8fd8\u4e0d\u4e00\u6837\uff1a<\/p>\n

    u00a0==’ ‘ mysql\u2705\uff0csqlserver\u274c
    u2000==’ ‘ mysql\u2705\uff0csqlserver\u274c
    u3000==’ ‘ mysql\u2705\uff0csqlserver\u2705<\/p>\n

    \u5b57\u7b26\u4e32\u9996\u5c3e\u7a7a\u683c\uff0c\u4f3c\u4e4e\u8fd8\u5f71\u54cd\u5230\u4e86 len \u3001length \u3001=\u3001!= \u3001in\uff0c\u592a\u53ef\u6015\uff0c\u8fd9\u79cd\u529f\u80fd\u5374\u4e0d\u662f\u53e6\u5916\u5f00\u4e00\u4e2a\u660e\u786e\u8868\u610f\u7684\u51fd\u6570\u6765\u505a\uff0c\u9ed1\u6697\u3001\u53ef\u6015 <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : DonaldY <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6240\u4ee5\uff0c\u8fd9\u79cd\u9700\u8981 group by \u7684\u5b57\u6bb5\uff0c\u4e3a\u4ec0\u4e48\u4f1a\u51fa\u73b0 \u7a7a\u683c\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : philchang1995 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @DonaldY \u8868\u8bbe\u8ba1\u7684\u65f6\u5019\u80fd\u628a\u540e\u7eed\u6240\u6709\u9700\u6c42\u90fd\u8003\u8651\u5230\u4e48\uff1f <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : telung <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u53d1\u73b0\u4e86\u8fd9\u4e48\u5927\u7684 BUG, \u5feb\u63d0\u7ed9 MYSQL \u56e2\u961f\uff0c\u5fae\u8f6f\u516c\u53f8\u554a <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : liprais <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4f60\u7528\u7684\u662f varchar \u8fd8\u662f char? <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : nikan999 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u8fd9\u79cd\u60c5\u51b5 \u662f\u4e0d\u662f\u8003\u8651\u6570\u636e\u4e25\u683c\u76f8\u7b49\u6bd4\u8f83\u597d\uff0c\u4e0d\u8981\u53bb\u4f9d\u8d56\u6570\u636e\u5e93\u7684\u5177\u4f53\u5b9e\u73b0 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : xiangyuecn <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @DonaldY #3 \u6211\u4e5f\u4ee5\u4e3a\u662f group by \u6709\u5f71\u54cd\uff0c\u4f46 len \u3001length \u3001=\u3001!= \u90fd\u6709\u5f71\u54cd\u3002\u5e76\u4e14\u7a7a\u683c\u8fd9\u4e2a\u5b9a\u4e49\u592a\u5bbd\u6cdb\uff0c\u4e0d\u540c\u8bed\u8a00\u5b9e\u73b0\u5b8c\u5168\u4e0d\u4e00\u81f4\uff0c\u6570\u636e\u5e93\u89c4\u8303\u5b8c\u5168\u662f\u5728\u6316\u5751\u3002<\/p>\n

    js \u53ef\u4ee5 trim \u6389\u5e38\u89c1\u4f46\u53c8\u6572\u4e0d\u51fa\u7684\u7a7a\u683c\uff0c\u5982\u6211 2 \u8fd9 3 \u4e2a<\/p>\n

    java \u53ea\u80fd trim \u6389 u0020 \u952e\u76d8\u6572\u51fa\u6765\u7684\u8fd9\u4e2a\u7a7a\u683c\uff0c\u5176\u4ed6\u7a7a\u683c trim \u4e0d\u6389<\/p>\n

    \u5176\u4ed6\u8bed\u8a00\u6ca1\u6d4b\u8bd5 trim\uff0c\u53cd\u6b63\u603b\u6709\u4e2a\u5730\u65b9\u4f1a\u8ba9\u4f60\u8df3\u8fdb\u53bb <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : xiangyuecn <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @telung #5 \u522b\u95f9 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : xiangyuecn <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @nikan999 #7 \u55ef\uff0c\u8fd9\u662f\u9ed8\u8ba4\u60c5\u51b5\u4e0b\u624d\u4f1a\u51fa\u73b0\u7684\u5751\uff0c\u5982\u679c\u6211\u8981\u7279\u610f\u53bb\u89c4\u907f\uff0c\u81ea\u7136\u6709\u5f88\u591a\u529e\u6cd5\u3002\u4f46\u8fd9\u79cd\u9ed8\u8ba4\u8ba9\u666e\u901a\u7684\u5efa\u8868\u3001\u67e5\u8be2\u5f88\u53d7\u4f24 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : syozzz <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4ece\u6765\u8fd8\u6ca1\u6ce8\u610f\u8fc7\u8fd9\u4e2a\u95ee\u9898== <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : CRVV <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    https:\/\/www.postgresql.org\/docs\/current\/datatype-character.html<\/p>\n

    \u7f51\u9875\u5185\u641c\u7d22 SQL standard
    This somewhat bizarre exception is required by the SQL standard<\/p>\n

    \u901a\u5e38\u90fd\u7528 VARCHAR \u7684\uff0c\u6ca1\u8fd9\u4e2a\u95ee\u9898<\/p>\n

    \u6216\u8005\u4e0a PostgreSQL \u5168\u7528 TEXT \u5b8c\u4e8b\u3002 <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : xuanbg <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5f80\u540e\u7aef\u4f20\u7684\u65f6\u5019\u90fd\u4e0d trim \u6389\u9996\u5c3e\u7a7a\u683c\u7684\u5417\uff1f <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : PopRain <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4fdd\u5b58\u6570\u636e\u65f6\u968f\u4fbf\u4fdd\u5b58\uff0c\u4e0d\u6ce8\u610f\u89c4\u8303\u6570\u636e\uff0c\u56de\u5934\u53cd\u8fc7\u6765\u8d56\u6570\u636e\u5e93\u2026\u2026\u2026\u5c3e\u90e8\u7a7a\u683c\u5ffd\u7565\u6389\u7684\u4e3b\u8981\u539f\u56e0\u662f\u6700\u65e9\u6570\u636e\u5e93\u5927\u90e8\u5206\u7528\u56fa\u5b9a\u957f\u5ea6\u7684 Char \u7c7b\u578b\uff0c\u5ffd\u7565\u5c3e\u90e8\u7a7a\u683c\u65b9\u4fbf\u6bd4\u8f83\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : xiangyuecn <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @PopRain \u5178\u578b\u7684\u4ee5\u504f\u6982\u5168 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : xiangyuecn <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @PopRain \u53cd\u5012\u662f\u65e9\u671f char \u7c7b\u578b\uff0c\u5982\u679c\u7a0b\u5e8f\u5b58\u5165\u7684\u4e0d\u662f\u56fa\u5b9a\u957f\u5ea6\uff0c\u4f9d\u8d56\u6570\u636e\u5e93\u6765\u4fdd\u8bc1\u957f\u5ea6\u4e00\u81f4\u6027\uff0c\u90a3\u624d\u662f\u771f\u6b63\u7684\u4e71\u5b58\u6570\u636e\u5427 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : PopRain <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    SQL Server follows the ANSI\/ISO SQL-92 specification (Section 8.2, <Comparison Predicate>, General rules #3) on how to compare strings with spaces. The ANSI standard requires padding for the character strings used in comparisons so that their lengths match before comparing them. The padding directly affects the semantics of WHERE and HAVING clause predicates and other Transact-SQL string comparisons. For example, Transact-SQL considers the strings ‘abc’ and ‘abc ‘ to be equivalent for most comparison operations.<\/p>\n

    The only exception to this rule is the LIKE predicate. When the right side of a LIKE predicate expression features a value with a trailing space, SQL Server does not pad the two values to the same length before the comparison occurs. Because the purpose of the LIKE predicate, by definition, is to facilitate pattern searches rather than simple string equality tests, this does not violate the section of the ANSI SQL-92 specification mentioned earlier. <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : EminemW <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4e3a\u5565\u6570\u636e\u5e93\u4f1a\u5b58\u9996\u5c3e\u6709\u7a7a\u683c\u7684\u5b57\u7b26\u4e32\uff0c\u662f\u6709\u4ec0\u4e48\u7279\u6b8a\u4f5c\u7528\u5417 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : gulu <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u660e\u660e\u5c31\u662f\u6570\u636e\u5e93\u884c\u4e3a\u4e0d\u7b26\u5408\u9884\u671f\uff0c\u5404\u79cd\u602a\u6570\u636e\u81ea\u8eab\u4e0d\u89c4\u8303\u7684\u3002
    \u5c31 “ABC” \u80fd\u505a\u5b57\u7b26\u4e32\uff0c” ABC” \u5c31\u4e0d\u914d\uff1f <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"

    \u53d1\u73b0\u591a\u79cd\u6570\u636e\u5e93 group by …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/193287"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=193287"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/193287\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=193287"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=193287"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=193287"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}