sql自定义函数计算总数

create function getSum(@date date)
returns decimal(18,2)
as
begin
    declare @number decimal(18,2)=0
    while(@date<='2020/10/30')
    begin
        declare @tempdata decimal(18,2)=(select CZ_Amount from CZ_ProcessData where BV_VarName='E12M_RN111811' and CZ_Date=year(@date)*10000 + month(@date)*100 + day(@date))
        declare @totaltime decimal(18,2)=(case when @tempdata is null or @tempdata=0 then 0 else @tempdata end)
        set @number+=@totaltime
        set @date=dateadd(day,1,@date)
    end
    return @number
end

select dbo.getSum('2020/9/2') total

注意returns后面加的是数据类型