How to Get Index Fragmentation in SQL Server

Write below query to find Index fragmentation.
 
  SELECT ps.database_id, ps.OBJECT_ID,object_name(ps.object_id) AS [TableName],
 ps.index_id, b.name,
 ps.avg_fragmentation_in_percent
 FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL, NULL, NULL) AS ps
 INNER JOIN sys.indexes AS b ON ps.OBJECT_ID = b.OBJECT_ID
 AND ps.index_id = b.index_id
 WHERE ps.database_id = DB_ID() and b.name is not null
 ORDER BY ps.avg_fragmentation_in_percent desc
 GO
 
 It will return TableName, IndexId ,  Name ,Index Fragmentation.
 
 Now we can easily read the fragmentation and rebuild , reorganize indexes to get high performance.
 
 If Index fragmentation is more than 20 it is totally disable for sql table. I think this is a good practice to get fragmentation percentage and rebuild , reorganize indexes.