SQL Server十进制变量分配？ [英] SQL Server decimal variable assignment?

问题描述

我正在尝试编写一个存储过程，但是我得到了意外的除以0的异常。

I'm trying to write a stored procedure and I'm getting unexpected divide by 0 exceptions.

我将其范围缩小到以下示例。

I've narrowed it down to the following example.

为什么要这样做：

    declare @A decimal;
    declare @B decimal;
    declare @C decimal;

    set @A = 4;
    set @B = 9;
    set @C = @A/@B 

    select @A/@B as 'Expected'
    select @C as 'Wut'

导致此结果？

    Expected
    ---------------------------------------
    0.4444444444444444444

    (1 row(s) affected)

    Wut
    ---------------------------------------
    0

    (1 row(s) affected)

推荐答案

问题是您尚未为十进制类型指定比例。来自 MSDN ：

The problem is that you haven't specified a scale for the decimal type. From MSDN:

s（scale）

将要存储在右边的小数位数小数点的从p中减去此数字可确定小数点左边的最大位数。小数位数必须是0到p之间的值。仅在指定精度的情况下才能指定比例。 默认比例为0 ；因此，0< = s< = p。

The number of decimal digits that will be stored to the right of the decimal point. This number is substracted from p to determine the maximum number of digits to the left of the decimal point. Scale must be a value from 0 through p. Scale can be specified only if precision is specified. The default scale is 0; therefore, 0 <= s <= p.

因此，当您尝试存储 @ A / @ B 返回到 @C ，小数部分被截断。

So when you try to store @A/@B back into @C, the fractional part gets truncated.

注意：

declare @A decimal(18, 3);
declare @B decimal(18, 3);
declare @C decimal(18, 3);

set @A = 4;
set @B = 9;
set @C = @A/@B 

select @A/@B -- 0.44444444444444444444
select @C    -- 0.444

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