如何正确使用输出参数作为变量

Question

我有这个代码

DECLARE @columnName varchar(25)
DECLARE @cursor CURSOR
DECLARE @sql nvarchar(1000)
DECLARE @tableName as nvarchar(30)
DECLARE @PartNo as nvarchar(30)
DECLARE @value as integer

set @PartNo = 'partnumber'
set @tableName = 'sometable'

SET @cursor = CURSOR FOR 
                  SELECT c.name 
                  FROM sys.columns c 
                  INNER JOIN sys.tables t ON c.object_id = t.object_id 
                  WHERE c.object_id = (SELECT object_id FROM sys.tables 
                                       WHERE name  = @tableName)
                    AND c.name NOT IN ('something')

OPEN @cursor

FETCH NEXT FROM @cursor INTO @columnName

WHILE @@FETCH_STATUS = 0
BEGIN
    SET @sql = 'select sum('+@columnName+') from checktime where partNo = '''+@PartNo+''''

    EXEC sp_executesql @sql, N'@columnName varchar(25), @PartNo nvarchar(30), @value int OUTPUT',
                   @columnName,
                   @PartNo,
                   @value OUTPUT

    FETCH NEXT FROM @cursor INTO @columnName
END

CLOSE @cursor
DEALLOCATE @cursor

这段代码的问题是，即使我不想输出变量，它也已经输出了。我想使用这样的代码

 DECLARE @columnName varchar(25)
    DECLARE @cursor CURSOR
    DECLARE @sql nvarchar(1000)
    DECLARE @tableName as nvarchar(30)
    DECLARE @PartNo as nvarchar(30)
    DECLARE @value as integer

    set @PartNo = 'partnumber'
    set @tableName = 'sometable'
    SET @cursor = CURSOR FOR 
    select c.name from sys.columns c inner join sys.tables t on c.object_id = t.object_id 
    where c.object_id = (select object_id from sys.tables where name  = @tableName )
    and c.name not in ('something')

    OPEN @cursor

    FETCH NEXT

    FROM @cursor INTO @columnName
    WHILE @@FETCH_STATUS = 0
    BEGIN


    set @sql = 'select sum('+@columnName+') from checktime where partNo = '''+@PartNo+''''

    EXEC sp_executesql @sql, N'@columnName varchar(25), @PartNo nvarchar(30), @value int OUTPUT',
                       @columnName,
                       @PartNo,
                       @value OUTPUT

select case when @value > 0 then 'YEY' end 

    FETCH NEXT
    FROM @cursor INTO @columnName
    END

    CLOSE @cursor
    DEALLOCATE @cursor

我正在创建一个存储过程，用于搜索列名是否为 NULL，如果是，我会将其放入我的 select 语句中。我正在构建一个动态 SQL，其中输出将只生成所有不为空的表，但是这个任务，我将自己创建它，我只想知道如何操作 OUTPUT 变量。

Answer 1

J

在您的 sp_executesql 中，@value 参数未以任何方式使用。这是没用的。所以你可以修改你的初始如下

set @sql = 'select sum('+@columnName+'), 5 from CursorQ where partNo = '''+@PartNo+''' having sum('+@columnName+') > 0'
EXEC sp_executesql @sql, N'@columnName varchar(25), @PartNo nvarchar(30)',
                   @columnName,
                   @PartNo--, @value OUTPUT

你看我已经放置了一个带有 HAVING 子句的过滤条件

另一个选项是使用@value 参数。您可以修改脚本以使用@value，如下所示

set @sql = 'set @value = (select sum('+@columnName+') from CursorQ where partNo = '''+@PartNo+''')'
EXEC sp_executesql @sql, N'@columnName varchar(25), @PartNo nvarchar(30), @value int OUTPUT',
                   @columnName,
                   @PartNo, 
                   @value OUTPUT

                   if isnull(@value,0)>0
                    select @value where isnull(@value,0)>0

你可以意识到我将 SUM 值分配给输出然后在下面 SELECT 我使用了一个 IF 子句检查 @value 是否不为空且大于零（在 SELECT WHERE 子句是多余的，但您可以更喜欢使用 WHERE 而不是 IF)

如何正确使用输出参数作为变量

how to properly use output parameter as variable

tsql

sql-server

sql-server-2008-r2