DBCC (Database Consistency Checker Commands) is used to check logical and physical

consistency of database structure.DBCC statements can fix and detect problems.They

are grouped in to four categories :-

– Maintenance commands like DBCC DBREINDEX , DBCC DBREPAR etc ,

– Miscellaneous commands like DBCC ROWLOCK , DBCC TRACEO etc ,

they are mainly used for maintenance tasks in SQL SERVER.

they are mainly used for enabling row-level locking or removing DLL from

memory.

they are mainly used for checking status of the database.

CHECKCATALOG etc , they perform validation operations on database.

– Status Commands like DBCC OPENTRAN , DBCC SHOWCONTIG etc ,

– Validation Commands like DBCC CHECKALLOC,DBCC

Note :- Check MSDN for list of all DBCC commands, it is very much possible specially

during DBA interviews they can ask in depth individual commands.

Below is a sample screen in which DBCC SHOWCONTIG command is run. DBCC

SHOWCONTIG is used to display fragmentation information for the data and indexes

of the specified table.In the sample screen “Customer” table is checked for fragmentation

information. If you look at the figure “Scan density” is 100 if everything isucontigious in

this image it is 95.36% which is decent percentage. So such type of useful information

can be collected by DBCC command and database performance and maintenance can be

improved.