如何＆＃34;崩溃＆＃34;行？

Question

所以，如果我当前的结果集是：

 Set  |  Label  |  Val
------------------------
  A   |  "LabA" |  NULL
  A   |  "LabA" |   1
  A   |  "LabB" |  NULL
  A   |  "LabB" |   2
  B   |  "LabA" |  NULL
  B   |  "LabA" |   3
  B   |  "LabC" |  NULL

我真正想要的是：

 Set  |  Label  |  Val
------------------------
  A   |  "LabA" |   1
  A   |  "LabB" |   2
  B   |  "LabA" |   3
  B   |  "LabC" |  NULL

我怎能＆＃34;崩溃＆＃34;获取所需结果集的行？

Answer 1

您只需要在Set和Label列上使用MAX()进行GROUP BY汇总：

Select  Set, Label, Max(Val) Val
From    YourTable
Group By Set, Label
Order By Set, Label