SQL - 如果计数结果= 0，则运行第二个查询

Question

我的SELECT查询都在下面工作，并将返回值作为两个单独的结果。我想要做的是，如果第一个SELECT语句返回一个0，并且有时候是由于我们工作的性质，我希望第二个SELECT语句忽略第一个返回零，如果可能的话。如果第一个返回大于零的结果，那么我不希望第二个运行。

我一直在寻找和尝试不同的IF ELSE等，但由于使用的具体日期/时间公式，我认为这可能是不可能的，或者我可能不得不重写。这是有目的的，但我不会让你生气。提前致谢！

Declare @StartDate as DateTime 
Declare @EndDate as DateTime 
Declare @TodaysDate as DateTime 
Declare @Previous as DateTime 
Declare @Previous2 as DateTime 

set @TodaysDate = GETDATE() 
set @Previous = DATEADD(day,-1,@TodaysDate) 
set @Previous2 = DATEADD(day,-2,@TodaysDate) 

-- SELECT Statetment one starts here 

set @StartDate = cast(convert(varchar(4), datepart(yyyy, getdate())) + '-' + 
convert(varchar(2), datepart(mm, @Previous)) + '-' + 
convert(varchar(2), datepart(dd, @Previous)) + ' ' + 
'05:00' as datetime) 
set @EndDate = cast(convert(varchar(4), datepart(yyyy, getdate())) + '-' + 
convert(varchar(2), datepart(mm, @Previous)) + '-' + 
convert(varchar(2), datepart(dd, @Previous)) + ' ' + 
'16:59' as datetime) 

SELECT Count(*) as FirstShfitPrevious 
FROM [TOL_PROD_DB].[dbo].[tblLOT_CTRL_Active_Component] 
WHERE Close_Time_Stamp between @StartDate and @EndDate 

-- Query 2 Starts, Declarations already made at beginning 

set @StartDate = cast(convert(varchar(4), datepart(yyyy, getdate())) + '-' + 
convert(varchar(2), datepart(mm, @Previous2)) + '-' + 
convert(varchar(2), datepart(dd, @Previous2)) + ' ' + 
'05:00' as datetime) 
set @EndDate = cast(convert(varchar(4), datepart(yyyy, getdate())) + '-' + 
convert(varchar(2), datepart(mm, @Previous2)) + '-' + 
convert(varchar(2), datepart(dd, @Previous2)) + ' ' + 
'16:59' as datetime) 

SELECT Count(*) as FirstShfitPrevious2 
FROM [TOL_PROD_DB].[dbo].[tblLOT_CTRL_Active_Component] 
WHERE Close_Time_Stamp between @StartDate and @EndDate 

Answer 1

你可以试试你的第一个查询结果的值存储在一个变量，然后再检查值一样

declare @myVar int 

SELECT @myVar = Count(*) as FirstShfitPrevious 
FROM [TOL_PROD_DB].[dbo].[tblLOT_CTRL_Active_Component] 
WHERE Close_Time_Stamp between @StartDate and @EndDate) 

if(@myVar = 0) 
//Here your second query logic 
begin 
set @StartDate = cast(convert(varchar(4), datepart(yyyy, getdate())) + '-' + 
convert(varchar(2), datepart(mm, @Previous2)) + '-' + 
convert(varchar(2), datepart(dd, @Previous2)) + ' ' + 
'05:00' as datetime) 
set @EndDate = cast(convert(varchar(4), datepart(yyyy, getdate())) + '-' + 
convert(varchar(2), datepart(mm, @Previous2)) + '-' + 
convert(varchar(2), datepart(dd, @Previous2)) + ' ' + 
'16:59' as datetime) 

SELECT Count(*) as FirstShfitPrevious2 
FROM [TOL_PROD_DB].[dbo].[tblLOT_CTRL_Active_Component] 
WHERE Close_Time_Stamp between @StartDate and @EndDate 
end 

Answer 2

使用NOT EXISTS ..

if NOT Exists 
(Select 1 as FirstShfitPrevious--first query 
FROM [TOL_PROD_DB].[dbo].[tblLOT_CTRL_Active_Component] 
WHERE Close_Time_Stamp between @StartDate and @EndDate 
) 
Begin 
SELECT Count(*) as FirstShfitPrevious2--second query 
FROM [TOL_PROD_DB].[dbo].[tblLOT_CTRL_Active_Component] 
WHERE Close_Time_Stamp between @StartDate and @EndDate 
END 
Else 
Begin 
--First query 
End 

Answer 3

甚至这种方式：

SELECT TOP 1 Count(*) as FirstShfitPrevious2 
FROM [TOL_PROD_DB].[dbo].[tblLOT_CTRL_Active_Component] 
WHERE Close_Time_Stamp between @StartDate and @EndDate 
GROUP BY CAST(Close_Time_Stamp AS DATE) 
ORDER BY CAST(Close_Time_Stamp AS DATE) DESC 

与牙周d涵盖两个日期范围。