Question

I have a SQL Server 2005 database that stores data for multiple users. Each table that contains user-owned data has a column called OwnerID that identifies the owner; most but not all tables have this column.

I want to be able to count number of rows ‘owned’ by a user in each table. In other words, I want a query that returns the names of each table that contains an OwnerID column, and counts the number of rows in each table that match a given OwnerID value.

I can return just the names of the matching tables using this query:

SELECT OBJECT_NAME(object_id) [Table] FROM sys.columns 
    WHERE name = 'OwnerID' ORDER BY OBJECT_NAME(object_id);

That query returns a list of table names like this:

+---------+
|  Table  |
+---------+
| Alpha   |
| Beta    |
| Gamma   |
| ...     |
+---------+

But is it possible to write a query that can also count the number of rows in each table that match a given OwnerID? ie:

+---------+------------+
|  Table  |  RowCount  |
+---------+------------+
| Alpha   | 2042       |
| Beta    | 49         |
| Gamma   | 740        |
| ...     | ...        |
+---------+------------+

Note: The list of table names needs to be returned dynamically, it is not suitable to hard-code table names into this query.

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Edit: the answer…

(I can’t edit your answers yet but I can edit my own question so I’m putting it here…)

Damien_The_Unbeliever had essentially the correct answer, but SQL Server doesn’t allow string concatenation in an exec statement so I had to set the query prior to the exec statement. The final query is as follows:

DECLARE @OwnerID int;
SET @OwnerID = 1;

DECLARE @ForEachSQL varchar(100);
SET @ForEachSQL = 'INSERT INTO #t(TableName,RowsOwned) SELECT ''?'', COUNT(*) FROM ? WHERE OwnerID = ' + CONVERT(varchar(11), @OwnerID);

CREATE TABLE #t(TableName sysname, RowsOwned int);
EXEC sp_MSforeachtable @ForEachSQL, 
    @whereAnd = 'AND o.id IN (SELECT id FROM syscolumns where name=''OwnerID'')';
SELECT * FROM #t ORDER BY TableName;
DROP TABLE #t;

Answer 1

You can use sp_MSForeachtable, and the @whereand parameter, to specify a filter so you’re only working against tables with an OwnerID column. Create a temp table, and populate that for each matching table. Something like:

create table #t(tablename sysname,Cnt int)
sp_MSforeachtable 'insert into #t(tablename,Cnt) select ''?'',COUNT(*) from ?',@whereAnd='and o.id in (select id from syscolumns where name=''OwnerID'')'
select * from #t

Two major caveats to mention – first is that sp_MSforeachtable is “undocumented”, so you use it at your own risk – it could be suddenly removed from SQL Server by any kind of servicing, or in the next release.

The second is that, having a dynamic schema is usually a sign that something else has gone wrong in modelling – possibly attribute splitting (where sales for January and February are given different tables, even though they’re logically the same thing and should appear in the same table, with possibly an additional column to distinguish them)

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And, of course, you wanted to filter based on a particular clientID, so the query would be more like:

'insert into #t(tablename,Cnt) select ''?'',COUNT(*) from ? where OwnerID=' + @OwnerID

(Assuming @OwnerID is the owner sought, and is an int)