使用了微软提供的不公开的存储过程sp_MSforeachtable
EXEC sp_MSforeachtable'INSERT INTO #temp (TableName,RowsCnt,ReservedSpace,DataSpace,CombinedIndexSpace,UnusedSpace) EXEC sp_spaceused ''?'',FALSE'
SELECT TableName,UnusedSpace
FROM #temp
ORDER BY TableName
DROP TABLE #temp