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Executing a stored procedure in another database with parameters

I need to get the table column names that are in another database. A script is running for the active database, but I need to run it with a different database in the same server instance:

SELECT @ColumnList = 
    CASE
        WHEN @ColumnList IS NULL THEN name
        WHEN @ColumnList IS NOT NULL THEN @ColumnList + ',' + name
    END
FROM sys.columns
WHERE object_id = Object_Id(@TableName);

Here's the problem ... the database is unknown at compile time. It is passed to the stored procedure at runtime. Therefore, I see no alternative but to use dynamic sql. I used to try to use a Use [DBName]script in dynamic sql, but I always ran into problems until I realized that I could do this:

SET @SQL = 'SELECT Foo FROM Bar'
SET @sp_executesql = quotename(@DatabaseName) + '..sp_executesql'
EXECUTE @sp_executesql @SQL

But it’s hard for me to figure out how to do this with the script I mentioned above. My first attempt looked like this:

-- @DatabaseName and @TableName are parameters of the 
-- stored procedure containing this script

DECLARE @ColumnList nvarchar(max),
        @SQL nvarchar(max),
        @sp_executesql nvarchar(max) = quotename(@DatabaseName) + '..sp_executesql';
SET @SQL = 
'SELECT @ColumnList = 
    CASE
        WHEN @ColumnList IS NULL THEN name
        WHEN @ColumnList IS NOT NULL THEN @ColumnList + '','' + name
    END
FROM sys.columns
WHERE object_id = Object_Id(@TableName);'

EXECUTE @sp_executesql @SQL,
        N'@ColumnList = nvarchar(max) OUT, @TableName = sysname',
        @ColumnList, @TableName

, @ColumnList . ?

+3
2

, , :

-- I assume these are parameters, so declaring them separately:
DECLARE 
    @DatabaseName SYSNAME = N'db_name',
    @TableName SYSNAME = N'table_name';

DECLARE 
    @sql NVARCHAR(MAX), 
    @columnList NVARCHAR(MAX);

SELECT @sql = N'SELECT @ColumnList = COALESCE(@ColumnList + '','', '''') 
    + c.name
    FROM [$db$].sys.columns AS c
    INNER JOIN [$db$].sys.tables AS o
    ON c.[object_id] = o.[object_id]
    WHERE o.name = @TableName;';

SET @sql = REPLACE(@sql, '$db$', @DatabaseName);

EXEC sp_executesql @sql, 
    N'@ColumnList NVARCHAR(MAX) OUTPUT, @TableName SYSNAME',
    @ColumnList OUTPUT, @TableName;

SELECT @ColumnList
+2

= @params OUT OUTPUT @ColumnList.

:

EXECUTE @sp_executesql @SQL,
        N'@ColumnList nvarchar(max) OUT, @TableName sysname',
        @ColumnList OUT, @TableName

:

EXECUTE @sp_executesql @SQL,
        N'@ColumnList = nvarchar(max) OUT, @TableName = sysname',
        @ColumnList, @TableName
+1

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