database fragmentation

frag.sql

SELECT name, avg_fragmentation_in_percent
FROM sys.dm_db_index_physical_stats (
       DB_ID(N'PrePurchasing')
     , OBJECT_ID('PrePurchasing')
     , NULL
     , NULL
     , NULL) AS a
JOIN sys.indexes AS b 
ON a.object_id = b.object_id AND a.index_id = b.index_id;