声明标量变量 SQL

Question

我的问题是我想在我的更新查询中使用这个局部变量，有没有办法做到这一点？

 DECLARE @listStr VARCHAR(MAX)
    SELECT @listStr = COALESCE(@listStr+''',''' , '') + cast(int_guid as varchar(max)) 
    FROM ex_in
    SELECT '''' + @listStr + ''''

更新查询

update dbo.ex_in
SET    int_action = CASE WHEN int_action = 120 THEN 110 WHEN int_action = 220 THEN 210 ELSE int_action END
WHERE  int_action IN (120,220)
       AND int_guid in(@listStr)

Answer 1

不，因为字符串变量上的 in 不符合您的预期。

但是，为什么要为变量烦恼呢？只要做：

update dbo.ex_in
    SET int_action = (CASE WHEN int_action = 120 THEN 110 WHEN int_action = 220 THEN 210 ELSE int_action END)
    WHERE int_action IN (120, 220) AND
          int_guid in (SELECT int_guid FROM ex_in);

当然，既然我写了这个，in逻辑就没有必要了，因为两个查询都在同一个table上，没有过滤。只需使用：

update dbo.ex_in
    SET int_action = (CASE WHEN int_action = 120 THEN 110 WHEN int_action = 220 THEN 210 ELSE int_action END)
    WHERE int_action IN (120, 220);

Answer 2

我能想到的做你想做的唯一方法是使用动态 SQL，像这样：

DECLARE @sql varchar(MAX);

SET @sql = '
UPDATE dbo.ex_in
SET    int_action = CASE WHEN int_action = 120 THEN 110 
                         WHEN int_action = 220 THEN 210 
                         ELSE int_action 
                    END;
WHERE  int_action IN (120,220)
       AND int_guid IN (' + @listStr + ')
';

EXEC @sql;

声明标量变量 SQL

Declare scalar variable SQL

sql

sql-server

variables

scalar

declare