Question

我有一个proc，我想添加一个参数 - 该参数将被称为@AmountType。我想将@AmountType参数添加到我的where子句中，以便我可以过滤不同的金额类型。棘手的部分是我希望@AmountType的值是我选择的case语句部分的结果。
因此，仅显示AmountType1记录，或仅显示AmountType2记录等。显然，我不能只where @AmountType = Amounts Amounts，因为ALTER PROCEDURE spProc1 @Date datetime AS BEGIN Select location, workDate, case when dollarAmount1 - dollarAmount2 < 0 Then 'AmountType1' when dollarAmount1 - dollarAmount2 > 0 Then 'AmountType2' when dollarAmount1 - dollarAmount2 = 0 Then 'AmountType3' End As Amounts From table1 Where @Date = workDate END不是真正的列。

有关如何实现这一目标的任何想法？

这是我的陈述：

{{1}}

Answer 1

如果您希望在可能的性能下降时避免重复代码，请使用子查询：

select
  location,
  workDate,
  Amounts
from (
    Select 
      location, 
      workDate, 
      case 
        when dollarAmount1 - dollarAmount2 < 0 Then 'AmountType1'
        when dollarAmount1 - dollarAmount2 > 0 Then 'AmountType2'
        when dollarAmount1 - dollarAmount2 = 0 Then 'AmountType3'            
      End As Amounts
    From
      table1
    Where
      @Date = workDate
) foo
where
  Amounts = @AmountType

否则重复代码：

Select 
  location, 
  workDate, 
  case 
    when dollarAmount1 - dollarAmount2 < 0 Then 'AmountType1'
    when dollarAmount1 - dollarAmount2 > 0 Then 'AmountType2'
    when dollarAmount1 - dollarAmount2 = 0 Then 'AmountType3'            
  End As Amounts
From
  table1
Where
  @Date = workDate
  and
  @AmountType = case 
    when dollarAmount1 - dollarAmount2 < 0 Then 'AmountType1'
    when dollarAmount1 - dollarAmount2 > 0 Then 'AmountType2'
    when dollarAmount1 - dollarAmount2 = 0 Then 'AmountType3'            
  End

然后，性能可能没有差别。

在Where子句中使用Select Case Statement中的结果字段

1 个答案: