{"id":128167,"date":"2020-06-16T09:46:22","date_gmt":"2020-06-16T01:46:22","guid":{"rendered":"http:\/\/4563.org\/?p=128167"},"modified":"2020-06-16T09:46:22","modified_gmt":"2020-06-16T01:46:22","slug":"%e6%9c%89%e4%b8%aa%e9%9c%80%e6%b1%82%e4%b8%8d%e7%9f%a5%e9%81%93%e6%80%8e%e4%b9%88%e5%86%99-sql%ef%bc%8c%e7%89%b9%e6%9d%a5%e8%af%b7%e6%95%99%e4%b8%80%e4%b8%8b","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=128167","title":{"rendered":"\u6709\u4e2a\u9700\u6c42\u4e0d\u77e5\u9053\u600e\u4e48\u5199 SQL\uff0c\u7279\u6765\u8bf7\u6559\u4e00\u4e0b"},"content":{"rendered":"<div>\n<div>\n<div>\n<h1>                  \u6709\u4e2a\u9700\u6c42\u4e0d\u77e5\u9053\u600e\u4e48\u5199 SQL\uff0c\u7279\u6765\u8bf7\u6559\u4e00\u4e0b               <\/h1>\n<p> <\/p>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <span><i><\/i> 80<\/span> <\/div>\n<div> <\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<div isfirst=\"1\"> <\/p>\n<p><img decoding=\"async\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2020\/06\/20200629_5ef9abf563d69.jpg\" alt=\"\u6709\u4e2a\u9700\u6c42\u4e0d\u77e5\u9053\u600e\u4e48\u5199 SQL\uff0c\u7279\u6765\u8bf7\u6559\u4e00\u4e0b\" \/><\/p>\n<p>\u5982\u56fe\u8868\u7ed3\u6784\uff0c\u73b0\u5728\u9700\u8981\u6839\u636e space_id&amp;user_id \u505a group by\uff0c\u7136\u540e\u67e5\u8be2 create_at \u6700\u5927\u7684\u90a3\u6761\u6570\u636e\uff0c\u88ab\u96be\u5012\u4e86\uff0c\u6709\u6ca1\u6709\u5927\u4f6c\u8d50\u6559\u4e00\u4e0b\u3002<\/p>\n<\/p><\/div>\n<div> <b>\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (<span>35<\/span>)        <\/div>\n<div> <\/div>\n<\/p><\/div>\n<\/p><\/div>\n<ul>\n<li data-pid=\"37576\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : alpha2016 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             SELECT space_id,user_id, max(created_at)<br \/>FROM table<br \/>GROUP BY space_id,user_id                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37577\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : ChoateYao <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             SELECT &#8230;.. ( SELECT &#8230;. ORDER BY create_at DESC) AS a GROUP BY space_id, user_id                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37578\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : srx1982 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u9700\u6c42\u6709\u95ee\u9898\u5427                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37579\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @alpha2016 #1 \u8fd9\u6837\u67e5\u51fa\u6765\u7684\u53ea\u662f create_at \u5b57\u6bb5\u4e3a\u6700\u5927\uff0c\u5176\u5b83\u5b57\u6bb5\u4e0d\u662f\u540c\u4e00\u6761\u8bb0\u5f55                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37580\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : hiths <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             SELECT<br \/> t2.* <br \/>FROM<br \/> ( SELECT space_id, user_id, max( create_at ) AS mx FROM TABLE GROUP BY space_id, user_id ) AS t1<br \/> LEFT JOIN TABLE AS t2 ON t2.space_id = t1.space_id <br \/> AND t2.user_id = t1.user_id <br \/> AND t2.create_at = t1.mx                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37581\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : hiths <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u4e0d\u5bf9\uff0c\u65f6\u95f4\u80fd max \uff08\uff09\u5417\u3002\u3002\u3002\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37582\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : Cooky <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u5b50\u67e5\u8be2\u5457                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37583\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : aragakiyuii <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u4ec0\u4e48\u6570\u636e\u5e93\uff1f<br \/>group by \u5b8c\u4e86 order by create_at desc\uff0c \u7136\u540e\u53d6\u7b2c\u4e00\u6761\u5c31\u884c\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37584\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @hiths #5 \u591a\u8c22\u8001\u94c1\uff0c\u8fd9\u6837\u53ef\u4ee5\uff0c\u6211\u770b\u770b\u80fd\u5426\u518d\u7b80\u5316\u4e00\u4e9b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37585\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : hiths <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @reidxx \u7b80\u5316\u5c31\u662f\u5199\u6210 where, \u4e0d\u8fc7\u6570\u636e\u91cf\u5927\u5c31\u86cb\u75bc\u4e86\u70b9                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37586\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : lensan <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             select max (created_at) ,space_id,user_id <br \/>from table t<br \/>join (<br \/> space_id,user_id from group by space_id,user_id <br \/>) t2 on t.space_id=t2.space_id and t.user_id =t2.user_id                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37587\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : zhesheng <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             select * from ( select a.*,row_number() over (partition by a.space_id,a.user_id order by a.create_at desc) rn from table_name a ) where rn =1                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37588\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @hiths #6 \u53ef\u4ee5\u7684\uff0c\u4f60\u4e0a\u9762\u90a3\u6761 sql \u6682\u65f6\u6765\u770b\u6ee1\u8db3\u9700\u6c42\uff0c\u6211\u8bd5\u8bd5\u589e\u52a0\u70b9\u6570\u636e\u9a8c\u8bc1\u4e00\u4e0b\u3002<\/p>\n<p>@aragakiyuii #8 mysql                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37589\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : lff0305 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             &#8220;`<br \/>select * from table as t<br \/> where (select count(distinct(e1.created_at)) from table as t1 where t1.space_id= e.space_id and t1.user_id<br \/> = t.user_id and t1.created_at &gt; t.created_at) &lt; 1;<br \/>&#8220;`<\/p>\n<p>\u6ca1\u8bd5\u9a8c\uff0c\u5927\u6982\u8fd9\u4e2a\u610f\u601d\uff0c\u6548\u7387\u4e0d\u9ad8                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37590\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : andj4cn <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             create_at \u4e5f\u9700\u8981 group by \u5427\uff0c\u5148 \u6839\u636e space_id, user_id, create_at \u8fdb\u884c group by\uff0c\u7136\u540e select * from () order by create_at desc limit 1                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37591\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @andj4cn #15 \u6bcf\u6761\u8bb0\u5f55\u7684 create_at \u57fa\u672c\u90fd\u4e0d\u4e00\u6837\uff0c\u52a0\u5165 group by \u7684\u8bdd\u5c31\u76f8\u5f53\u4e8e\u67e5\u5168\u90e8\u6570\u636e\u4e86\uff0c\u518d order by limit 1 \u5c31\u53ea\u8fd4\u56de\u4e00\u6761\u6570\u636e\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37592\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : dofine <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             row_number() over (partition by space_id, user_id order by create_at desc) <br \/>== \u62b1\u6b49\u5fd8\u8bb0\u597d\u50cf mysql \u4e0d\u652f\u6301\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37593\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : fox0001 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u5982\u679c\u662f SQL server\uff0c\u6211\u4f1a\u7528 row_number\u3002\u5177\u4f53\u5982\u4e0b<\/p>\n<p>select space_id, user_i<br \/>from(<br \/>select space_id, user_id, row_number()over(partition by space_id, user_id order by create_at desc) num<br \/>from &#8230;..<br \/>)a<br \/>where number=1                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37594\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : xuanbg <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u5982\u679c\u4f60\u7684\u6570\u636e\u53ea\u6709 space_id\u3001user_id\u3001create_at \u7684\u8bdd\uff0c1 \u5c31\u80fd\u6ee1\u8db3\u4f60\u7684\u8981\u6c42\u3002\u5982\u679c\u4e0d\u6b62\u8fd9 3 \u4e2a\u5b57\u6bb5\u7684\u8bdd\uff0c1 \u7684 sql \u5f53\u505a\u4e00\u4e2a\u5b50\u67e5\u8be2\uff0c\u7136\u540e\u7528\u8fd9\u4e2a\u7ed3\u679c\u53bb join \u539f\u8868\uff0con \u6761\u4ef6\u5c31\u662f\u8fd9 3 \u4e2a\u5b57\u6bb5\u5168\u5339\u914d\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37595\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : kiracyan <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u8fd9\u6837\uff1f \u5176\u5b9e\u6ca1\u592a\u770b\u61c2\u9700\u6c42<br \/>select * from t1<br \/>where not exists(select 1 from t2 where t1.user_id=t2.user_id and t1.space_id=t2.space_id and t1.create_at &lt;t2.create_at )                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37596\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : surfire91 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u5982\u679c\u540c\u4e00 space_id, user_id \u4e0b create_at \u6700\u5927\u7684\u6709\u591a\u6761\uff0c\u9700\u8981\u8fd4\u56de\u51e0\u6761\uff1f<br \/>\u5982\u679c\u53ea\u9700\u8981\u8fd4\u56de 1 \u6761\uff08\u8b6c\u5982 create_at \u6700\u5927\uff0cid \u6700\u5c0f\u7684 1 \u6761\uff09\u7684\u8bdd\u4e0a\u6709\u4e9b\u662f\u4e0d\u6ee1\u8db3\u9700\u6c42\u7684\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37597\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : ChoateYao <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u6211\u5728\u4e8c\u5df2\u7ecf\u56de\u7b54\u4e86\u8fd9\u4e2a\u95ee\u9898\uff0cMySQL \u7684 Group By \u7279\u6027\u5c31\u662f\u6839\u636e\u6570\u636e\u9ed8\u8ba4\u6392\u5e8f\uff0c\u53d6\u53bb\u91cd\u6570\u636e\u7684\u7b2c\u4e00\u6761\u3002<\/p>\n<p>\u6839\u636e\u8fd9\u4e2a\u7279\u6027\uff0c\u6211\u4eec\u5148\u5bf9\u6570\u636e\u8fdb\u884c\u6392\u5e8f\uff0c\u7136\u540e\u5728 Group By \u5373\u53ef\u5f97\u5230\u4f60\u60f3\u8981\u7684\u7ed3\u679c\u3002<\/p>\n<p>\u4f46\u662f\u5728 MariaDB \u4e2d\uff0c\u8be5\u65b9\u6cd5\u5e76\u4e0d\u8d77\u6548\u679c\uff0c\u9700\u8981\u989d\u5916\u5f15\u5165\u4e00\u4e2a\u83ab\u540d\u5176\u5999\u7684\u8bed\u53e5: LIMIT 18446744073709551615<\/p>\n<p>\u6240\u4ee5\u6700\u7ec8\u7684 SQL \u662f: SELECT &#8230;.. ( SELECT &#8230;. ORDER BY create_at DESC LIMIT 18446744073709551615) AS a GROUP BY space_id, user_id                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37598\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @ChoateYao #22 \u8fd8\u771f\u7684\u662f\uff0c\u52a0\u4e0a\u90a3\u6bb5 limit \u540e\u80fd\u67e5\u51fa\u6765\uff0c\u4e0d\u52a0 limit \u7684\u8bdd\uff0c\u67e5\u51fa\u6765\u7684\u662f min(create_at) \u7684\u6570\u636e\uff0c\u80fd\u89e3\u91ca\u4e0b\u90a3\u6bb5 limit \u5b50\u53e5\u662f\u5565\u610f\u601d\u5417\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37599\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u521a\u597d\u6211\u53f8\u7528\u7684\u662f mariadb..                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37600\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @hiths #5 22 \u5927\u4f6c\u7684 sql \u5f88\u7b80\u6d01\uff0c\u5e76\u6ee1\u8db3\u4e86\u9700\u6c42\uff0c\u53ef\u53c2\u8003\u4e00\u4e0b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37601\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : ChoateYao <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @reidxx https:\/\/mariadb.com\/kb\/en\/library\/why-is-order-by-in-a-from-subquery-ignored\/ \u8fd9\u91cc\u6709\u89e3\u91ca                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37602\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : x66 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             mariadb10.2 \u5f00\u59cb\u652f\u6301\u5f00\u7a97\u51fd\u6570\uff0c\u5982\u679c\u4f60\u7528\u7684\u662f 10.2 \u4ee5\u540e\u7684\u7248\u672c\uff0c\u53ef\u4ee5\u4e86\u89e3\u4e00\u4e0b\u5f00\u7a97\u51fd\u6570                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37603\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : Seayon <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u8fd9\u4e48\u770b\u770b oracle \u7684\u7a97\u53e3\u51fd\u6570\u8fd8\u771f\u662f\u628a\u4eba\u517b\u61d2\u4e86\uff0c\u6211\u53ea\u4f1a\u7528\u7a97\u53e3\u51fd\u6570\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37604\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : wc951 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u597d\u5de7\uff0c\u8fd9\u9700\u6c42\u6211\u521a\u505a\u8fc7<br \/>select t1.* from table t1,<br \/>(select space_id,user_id,max(create_at) as maxtime from table group by space_id,user_id) t2<br \/>where t1.space_id=t2.space_id and t1.user_id=t2.user_id and t1.create_at=t2.maxtime                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37605\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : reidxx <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @x66 #27 \u591a\u8c22\uff0c\u7814\u7a76\u4e00\u4e0b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37606\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : p1094358629 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u5199\u4e2a\u5b50\u67e5\u8be2\u554a                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37607\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : Yang857 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u7a97\u53e3\u51fd\u6570 row_number \u89e3\u51b3                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37608\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : levelworm <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             SELECT<br \/> t.*<br \/>FROM (<br \/> SELECT<br \/> t.*,<br \/> MAX(create_at) OVER(PARTITION BY space_id, user_id) AS max_create_at<br \/> FROM<br \/> table AS t<br \/>) AS a<br \/>INNER JOIN table AS t<br \/> ON t.space_id = a.space_id AND t.user_id = a.user_id AND t.create_at = a.max_create_at<\/p>\n<p>\u6216\u8005\u4e0a\u8bf4\u7684\u7a97\u53e3\u51fd\u6570\u66f4\u7b80\u5355<br \/>SELECT<br \/> t.*<br \/>FROM (<br \/> SELECT<br \/> t.*,<br \/> ROW_NUMBER() OVER(PARTITION BY space_id, user_id ORDER BY create_at DESC) AS row_num<br \/> FROM<br \/> table AS t<br \/>) AS a<br \/>WHERE<br \/> row_num = 1                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37609\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : ricky077 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             SELECT space_id,user_id<br \/>FROM table<br \/>GROUP BY space_id,user_id<br \/>having created_at = max(created_at)                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"37610\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : contmonad <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u6309 SQL \u6807\u51c6\u672c\u6765\u5c31\u4e0d\u80fd select \u4e0d\u5c5e\u4e8e group by \u7684\u5217\uff08\u5728\u5173\u7cfb\u4ee3\u6570\u4e0a\u6ca1\u6709\u610f\u4e49\uff09\uff0cMySQL \u539f\u5148\u652f\u6301\u8fd9\u79cd\u5199\u6cd5\u53ea\u662f\u5b83\u7684\u4e00\u4e2a\u6269\u5c55\uff0c\u5728 v5.7.5 \u4ee5\u540e \u9ed8\u8ba4\u5f00\u542f ONLY_FULL_GROUP_BY \u5c31\u4e0d\u80fd\u7528\u4e86\u3002\u5982\u679c\u4e0d\u7528\u7a97\u53e3\u51fd\u6570\uff0c\u8fd9\u4e2a\u95ee\u9898\u4e00\u822c\u662f\u5199 self-join \u6216\u8005\u4f7f\u7528\u53d8\u91cf\uff08\u975e\u58f0\u660e\u5f0f\uff09\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li>\n","protected":false},"excerpt":{"rendered":"<p>\u6709\u4e2a\u9700\u6c42\u4e0d\u77e5\u9053\u600e\u4e48\u5199 SQL\uff0c\u7279\u6765&hellip;<\/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\/128167"}],"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=128167"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/128167\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=128167"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=128167"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=128167"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}