如何添加標量變量並將結果存儲在另一個標量變量中

Question

declare @Maxamount int, 
     @month varchar, 
     @Duration int, 
     @iReturn int 

set @month = (select DATEPART(MM,start_date) from TC_Project_Referal where id_tc_projuser = @id_tc_projuser) 
set @Duration = (select fixeddDuration from TC_Project_Referal where id_tc_projuser = @id_tc_projuser) 

select @Maxamount = @month+@Duration-1 

子查詢返回的值超過1個。當子查詢遵循=，！=，<，< =，>，> =或當子查詢用作表達式時，這是不允許的。我在數據庫中有超過1條記錄。數據將根據ID顯示。我們也可以爲單一的身份證提供多條記錄。然後如何使用INTO

Answer 1

。

select DATEPART(MM,start_date) **into** @month from TC_Project_Referal where id_tc_projuser = @id_tc_projuser; 

select fixeddDuration **into** @Duration from TC_Project_Referal where id_tc_projuser = @id_tc_projuser; 

select @Maxamount := @month+@Duration-1; 

Answer 2

如果你的內部查詢恰好返回多行，您會收到以下錯誤

子查詢返回多個值。當 子查詢遵循=，！=，<，< =，>，> =或當子查詢用作 表達式時，這是不允許的。

確保查詢返回使用單記錄TOP子句

declare @Maxamount int, 
     @month varchar, 
     @Duration int, 
     @iReturn int 

set @month = (select TOP 1 DATEPART(MM,start_date) from TC_Project_Referal where id_tc_projuser = @id_tc_projuser order by start_date) 
set @Duration = (select TOP 1 fixeddDuration from TC_Project_Referal where id_tc_projuser = @id_tc_projuser order by id_tc_projuser) 

select @Maxamount = @month+@Duration-1