Query Which Indexes to Rebuild

SELECT 'ALTER INDEX [' + ix.name + '] ON [' + s.name + '].
[' + t.name + '] ' + CASE WHEN ps.avg_fragmentation_in_percent > 40
THEN 'REBUILD' ELSE 'REORGANIZE'
END + CASE WHEN pc.partition_count > 1 THEN ' PARTITION = ' + 
cast(ps.partition_number as nvarchar(max)) ELSE '' END
FROM sys.indexes AS ix INNER JOIN sys.tables t
       ON t.object_id = ix.object_id
INNER JOIN sys.schemas s
       ON t.schema_id = s.schema_id
INNER JOIN (SELECT object_id, index_id, avg_fragmentation_in_percent,
      partition_number FROM sys.dm_db_index_physical_stats (DB_ID(),
               NULL, NULL, NULL, NULL)) ps
       ON t.object_id = ps.object_id AND ix.index_id = ps.index_id
INNER JOIN (SELECT object_id, index_id, 
            COUNT(DISTINCT partition_number) 
              AS partition_count FROM sys.partitions
               GROUP BY object_id, index_id) pc
       ON t.object_id = pc.object_id AND ix.index_id = pc.index_id
WHERE  ps.avg_fragmentation_in_percent > 10 AND
   ix.name IS NOT NULL