Union of multiple sp_MSforeachdb result sets - sql

Question

I can successfully query the same table in multiple databases as follows:
DECLARE #command varchar(1000)
SELECT #command = 'select * from table'
EXEC sp_MSforeachdb #command
However, all of these results are, as expected, returned in different result windows. What's the easiest way to perform a union of all of these results?

Answer 1

Please stop using sp_MSforeachdb. For anything. Seriously. It's undocumented, unsupported, and spectacularly broken:
Making a more reliable and flexible sp_MSforeachdb
Execute a Command in the Context of Each Database in SQL Server
If you know that all databases have the same table (and that they all have the same structure!), you can do this:
DECLARE #sql NVARCHAR(MAX);
SET #sql = N'';
SELECT #sql = #sql + N'UNION ALL SELECT col1,col2 /*, etc. */
FROM ' + QUOTENAME(name) + '.dbo.tablename'
FROM sys.databases WHERE database_id > 4 AND state = 0;
SET #sql = STUFF(#sql, 1, 10, '');
EXEC sp_executesql #sql;
This ignores system databases and doesn't attempt to access any databases that are currently not ONLINE.
Now, you may want to filter this further, e.g. not include any databases that don't have a table called tablename. You'll need to nest dynamic SQL in this case, e.g.:
DECLARE #sql NVARCHAR(MAX);
SET #sql = N'DECLARE #cmd NVARCHAR(MAX);
SET #cmd = N'''';';
SELECT #sql = #sql + N'
SELECT #cmd = #cmd + N''UNION ALL
SELECT col1,col2 /*, etc. */ FROM '
+ QUOTENAME(name) + '.dbo.tablename ''
WHERE EXISTS (SELECT 1 FROM ' + QUOTENAME(name)
+ '.sys.tables AS t
INNER JOIN ' + QUOTENAME(name) + '.sys.schemas AS s
ON t.[schema_id] = s.[schema_id]
WHERE t.name = N''tablename''
AND s.name = N''dbo'');'
FROM sys.databases WHERE database_id > 4 AND state = 0;
SET #sql = #sql + N';
SET #cmd = STUFF(#cmd, 1, 10, '''');
PRINT #cmd;
--EXEC sp_executesql #cmd;';
PRINT #sql;
EXEC sp_executesql #sql;
This doesn't validate the column structure is compatible, but you'll find that out pretty quickly.

Answer 2

Another way to skin this cat is to use dynamic SQL:
DECLARE #sql varchar(max);
SELECT #sql = Coalesce(#sql + ' UNION ALL ', '') + 'SELECT list, of, columns FROM ' + QuoteName(name) + '.schema.table'
FROM sys.databases
;
PRINT #sql
--EXEC (#sql);

Answer 3

Had some collation issues and had to use
AND COLLATION_NAME = 'SQL_Latin1_General_CP1_CI_AS'