If using an older version of SQL Server,
DBCC SHOWCONTIG
Newer versions should use the dm_db_index_physical_stats
DECLARE @db_id SMALLINT;
DECLARE @object_id INT;
SET @db_id = DB_ID(N'AdventureWorks');
SET @object_id = OBJECT_ID(N'Production.Customers');
IF @object_id IS NULL
BEGIN
PRINT N'Invalid object';
END
ELSE
BEGIN
SELECT IPS.Index_type_desc,
IPS.avg_fragmentation_in_percent,
IPS.avg_fragment_size_in_pages,
IPS.avg_page_space_used_in_percent,
IPS.record_count,
IPS.ghost_record_count,
IPS.fragment_count,
IPS.avg_fragment_size_in_pages
FROM sys.dm_db_index_physical_stats(@db_id, @object_id, NULL, NULL , 'DETAILED') AS IPS;
END
GO
Reference