SQL:动态变量名 [英] SQL: Dynamic Variable Names

问题描述

我试图在存储过程中设置名称为动态的变量:

I am attempting to set variables whose names are dynamic in a stored procedure:

DECLARE @var01 varchar(50)  
DECLARE @var02 varchar(50) 
...
DECLARE @var30 varchar(50)
DECLARE @sql = varchar(max) 

DECLARE @loopcnter INT      

-- (Inside some loop where the loopcounter increments each iteration)
...
SET @sql = 'SET @var0'+CAST(@loopcntr AS Varchar)+'= '''+'somevalue'+''''
-- e.g.) SET @var01= 'somevale'
EXEC (@sql)

这不起作用，因为变量是在与动态 sql 不同的范围内声明的.

This doesn't work because the variables are declared in a different scope to that of the dynamic sql.

以这种方式动态设置变量的正确方法是什么?

What is the correct way to dynamically set variables in this manner?

推荐答案

好吧，它不漂亮，但你可以这样做:

Well, it is not pretty, but you can do:

if @loopcntr = 1
    set var01 = 'somevalue'
else if @loopcntr = 2
    set var02 = 'whatever'
else if . . .

这应该足够令人不快，您可能会想到替代方案.哦，这是一个很好的.定义一个表变量并为每个值添加行:

This should be sufficiently unpleasant that you might think of alternatives. Oh, here's a good one. Define a table variable and just add rows in for each value:

declare @vars table (
    id int identity(1, 1),
    loopcntr int,
    value varchar(255)
);

. . .
-- inside the loop
    insert into @vars(loopcntr, value)
        select @loopcntr, 'whatever';

当你想得到一个变量时，你可以这样做:

When you want to get a variable, you can do:

declare @var varchar(255);
select @var = value from @vars where loopcntr = <the one I want>;

这篇关于SQL:动态变量名的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！