在T-Sql的公用表表达式中使用IF ELSE语句

Question

我创建了CTE，并尝试使用以下方法删除表。 请注意，CTE表达式可以正常工作，但IF ELSE语句则不能。

IF 
with FinalSales (time, terminal_id, count) as
(
    select time, terminal_id, count(*)
    from Final_Sales
    group by time, terminal_id
    having count(*) = 1             -- condition here
)

delete Sales
from FinalSales
inner join Sales
    on Sales.[time] = FinalSales.[time] 
    and Sales.terminal_id = FinalSales.terminal_id

ELSE IF 

  with FinalSales (time, terminal_id, count) as
  (
    select time, terminal_id, count(*)
    from Final_Sales
    group by time, terminal_id
    having count(*) > 1              -- Condition here
  )
  delete Sales
  from FinalSales
  inner join Sales
      on Sales.[time] = FinalSales.[time] 
      and Sales.terminal_id = FinalSales.terminal_id

   delete #temp1
   from FinalSales
   inner join #temp1
        on #temp1.[time] = FinalSales.[time] 
        and #temp1.terminal_id = FinalSales.terminal_id

在第一个IF语句中，当count(*) = 1我删除一个表中的行，然后在ELSEIF语句中，当count > 1我要删除两个表中的行。 但是，我的方法行不通。

如何将其包装到IF ELSE语句中？ 还是有其他方法可以做到这一点？

整个查询结构简单，

if count(*) == 1:
   delete Sales
else if count(*) > 1:
   delete Sales, #temp1

这样的事情。 如何在t-sql中执行此操作？

任何想法，将不胜感激。

Answer 1

我认为这可能有效：

declare @count_of_duplicates int

set @count_of_duplicates = 

(select max(duplicate_count)
from
(       select time, terminal_id, count(*) as duplicate_count
        from Final_Sales
        group by time, terminal_id)  t1)

我们首先将参数设置为等于count(*)最大值。 如果存在重复项，则其值将大于1；否则，如果存在重复项，则其值为1。

然后我们可以开始我们的条件：

if @count_of_duplicates = 1

begin
with FinalSales (time, terminal_id, count) as
(
    select time, terminal_id, count(*)
    from Final_Sales
    group by time, terminal_id
)

delete Sales
from FinalSales
inner join Sales
    on Sales.[time] = FinalSales.[time] 
    and Sales.terminal_id = FinalSales.terminal_id
end

else if @count_of_duplicates > 1
begin
  with FinalSales (time, terminal_id, count) as
  (
    select time, terminal_id, count(*)
    from Final_Sales
    group by time, terminal_id
  )
  delete Sales
  from FinalSales
  inner join Sales
      on Sales.[time] = FinalSales.[time] 
      and Sales.terminal_id = FinalSales.terminal_id

   delete #temp1
   from FinalSales
   inner join #temp1
        on #temp1.[time] = FinalSales.[time] 
        and #temp1.terminal_id = FinalSales.terminal_id
end

我还没有机会解析它……让我知道它是否有效。

Answer 2

为什么不使用if exist（query）？

IF exists (
    select time, terminal_id 
    from Final_Sales 
    group by time, terminal_id 
    having count(*) = 1
) begin
    --query
end else begin
    --query
end