Negative unused space

I wrote simple script to check space used by tables:

CREATE TABLE #SpaceUsed(
TableName NVARCHAR(128),
NoOfRows INT,
Reserved NVARCHAR(18),
Data NVARCHAR(18),
Index_Size NVARCHAR(18),
Unused NVARCHAR(18)
)
GO
sp_msforeachtable "INSERT INTO #SpaceUsed EXEC sp_spaceused '?'"

SELECT * FROM #SpaceUsed

SELECT
CAST(Sum(CAST(Replace(Reserved,' KB','') AS INT)) AS NVARCHAR) + ' KB' AS TotalReserved,
CAST(Sum(CAST(Replace(Data,' KB','') AS INT)) AS NVARCHAR) + ' KB' AS TotalData,
CAST(Sum(CAST(Replace(Index_Size,' KB','') AS INT)) AS NVARCHAR) + ' KB' AS TotalIndex_Size,
CAST(Sum(CAST(Replace(Unused,' KB','') AS INT)) AS NVARCHAR) + ' KB' AS TotalUnused
FROM #SpaceUsed

DROP TABLE #SpaceUsed

and one of results looks strange to me:

TableName NoOfRows Reserved Data Index_Size Unused
--------------------------------------- ---- ------ ------ ------ ------
T_TableXX 50081 38024 KB 37432 KB 640 KB -48 KB

Anyone know reason of such result (negative value of unused space)?Use this :

CREATE TABLE #SpaceUsed(
TableName NVARCHAR(128),
NoOfRows INT,
Reserved NVARCHAR(18),
Data NVARCHAR(18),
Index_Size NVARCHAR(18),
Unused NVARCHAR(18)
)
GO
sp_msforeachtable "INSERT INTO #SpaceUsed EXEC sp_spaceused '?' ,@.updateusage='True'"

SELECT * FROM #SpaceUsed

SELECT
CAST(Sum(CAST(Replace(Reserved,' KB','') AS INT)) AS NVARCHAR) + ' KB' AS TotalReserved,
CAST(Sum(CAST(Replace(Data,' KB','') AS INT)) AS NVARCHAR) + ' KB' AS TotalData,
CAST(Sum(CAST(Replace(Index_Size,' KB','') AS INT)) AS NVARCHAR) + ' KB' AS TotalIndex_Size,
CAST(Sum(CAST(Replace(Unused,' KB','') AS INT)) AS NVARCHAR) + ' KB' AS TotalUnused
FROM #SpaceUsed

DROP TABLE #SpaceUsed|||Works fine. Thanx :)|||Originally posted by MST78
Anyone know reason of such result (negative value of unused space)? It happends all of the time if you don't regularly update your statistics. You can update a single table using UPDATE STATISTICS (http://msdn.microsoft.com/library/en-us/tsqlref/ts_ua-uz_1mpf.asp), or get them all at once if you have the time using DBCC UPDATEUSAGE (http://msdn.microsoft.com/library/en-us/tsqlref/ts_dbcc_24rp.asp).

-PatP