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MySQL分组排序(取第一或最后)
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MySQL分组排序(取第一或最后)
方法一:速度非常慢,跑了30分钟
SELECT custid, apply_date, rejectrule FROM ( SELECT *, IF ( @pkey <> custid, @rank := 1, @rank := @rank + 1 ) AS rank, @pkey := custid FROM ( SELECT custid, createTime, SUBSTR( createTime, 1, 10 ) AS apply_date, rejectRule, STATUS FROM ( SELECT * FROM credit.`apply` WHERE SUBSTR( createTime, 1, 10 ) >= '2019-10-26' AND custid <> "" AND SUBSTR( custid, 1, 2 ) = '10' ) t1, ( SELECT @pkey := 0, @rank = 0 ) t2 ) t ORDER BY custid, createTime DESC ) a HAVING rank = 1 AND STATUS <> 1 LIMIT 100;
方法二:非常快,约为1分钟
SELECT custid, apply_date, rejectrule , STATUS FROM ( SELECT custid, apply_date, rejectrule, STATUS FROM ( SELECT custid, CASE WHEN locate( '|', statuss ) > 0 THEN SUBSTR( statuss, 1, INSTR( statuss, '|' )- 1 ) ELSE statuss END AS STATUS, CASE WHEN locate( '|', apply_dates ) > 0 THEN SUBSTR( SUBSTR( apply_dates, 1, INSTR( apply_dates, '|' )- 1 ), 1, 10 ) ELSE SUBSTR( apply_dates, 1, 10 ) END AS apply_date, CASE WHEN locate( '|', rejectrules ) > 0 THEN SUBSTR( rejectrules, 1, INSTR( rejectrules, '|' )- 1 ) ELSE rejectrules END AS rejectrule FROM ( SELECT custid, group_concat( STATUS ORDER BY createTime DESC SEPARATOR '|' ) AS statuss, group_concat( SUBSTR( createTime, 1, 10 ) ORDER BY createTime DESC SEPARATOR '|' ) AS apply_dates, group_concat( rejectrule ORDER BY createTime DESC SEPARATOR '|' ) AS rejectrules FROM credit.`apply` WHERE SUBSTR( createTime, 1, 10 ) >= '2019-07-26' AND custid <> "" AND SUBSTR( custid, 1, 2 ) = '10' GROUP BY custid ) t ) tt ) b WHERE apply_date >= '2019-10-12' AND STATUS <> 1 LIMIT 100;
方法三:
MySQL新版本已经支持窗口函数:mysql8.0
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