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单一MySQL询问,检查另一个浏览表
原标题:Single MySQL query which checks another table for rows
  • 时间:2010-08-27 15:42:41
  •  标签:
  • mysql

我有一个用户表和一个付款表。 我需要一个问题单,列出在外勤付款Completed=1的支付表中有记录的用户。

这些是表格中的栏目(简化):

     Users: UserID, UserName
  Payments: PaymentID, UserID, PaymentCompleted

询问应当选择外地用户名称。

最佳回答
select distinct UserName
from Users left outer join Payments on Users.UserID = Payments.UserID
where PaymentCompleted is NULL or PaymentCompleted != 1
问题回答
  SELECT UserName
  FROM Users u
  WHERE NOT EXISTS(Select 1 
                   from Payments p 
                   Where p.UserId = u.UserId
                   AND p.PaymentCompleted = 1)

* 选自t_user T. 不存在T.userid的地方(见p.userid from t_ Remunerations t where PayCompleted=1)。

一项说明:对于大量记录来说,“不在”条款的计算效率低。 如果你开始看到业绩问题,你可能会想做一些令人振奋/重新设计的工作。





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