如何将SELECT出来的值赋给一个变量，我的这段存储过程中如何才能实现，帮我看看。

[whzq007]

CREATE proc P_Add_Sale_Detail
@P1 varchar(13),
@P2 varchar(8),
@P3 varchar(2),
@P4 numeric(13,4),
@P5 money,
@P6 money,
@P7 money,
@P8 money,
@P9 money,
@P10 numeric(13,4)
AS

declare
@UnitID varchar(2)
select @UnitID = [S_UnitID] from BD_UnitInfo where S_UnitName = @P3

INSERT INTO elitejxc..VC_Sale_Detail
("S_VoucherId",
"S_ItemId",
"S_UnitID",
"F_Amount",
"M_CostPrice",
"M_BasePrice",
"M_RealPrice",
"M_BaseMoney",
"M_RealMoney",
"F_Discount")

VALUES (@P1,@P2,@UnitID,@P4,@P5,@P6,@P7,@P8,@P9,@P10)

GO

[whzq007]

总是报错，说@UnitID中是空值。如何改？

[senhanxiao]

set @UnitID=''

[whzq007]

是如何写的呢

[撸大湿]

declare
@UnitID varchar(2)
select @UnitID = isnull([S_UnitID],'') from BD_UnitInfo where S_UnitName = @P3

[whzq007]

但实际上@UnitID里是有值的