DBCC stands for database consistency checker. We use these commands to check the consistency of the databases. Example, maintenance, validation task and status checks.

DBCC CHECKALLOC - Check consistency of disk allocation. DBCC CHECKCATALOG - Check catalog consistency DBCC CHECKCONSTRAINTS - Check integrity of table constraints. DBCC CHECKDB - Check allocation, and integrity of all objects. DBCC CHECKFILEGROUP - Check all tables and indexed views in a filegroup. DBCC CHECKIDENT - Check identity value for a table. DBCC CHECKTABLE - Check integrity of a table or indexed view. DBCC CLEANTABLE - Reclaim space from dropped variable-length columns. DBCC dllname - Unload a DLL from memory. DBCC DROPCLEANBUFFERS - Remove all clean buffers from the buffer pool. DBCC HELP - Help for DBCC commands. DBCC INPUTBUFFER - Display last statement sent from a client to a database instance. DBCC OPENTRAN - Display information about recent transactions. DBCC OUTPUTBUFFER - Display last statement sent from a client to a database instance. DBCC PROCCACHE - Display information about the procedure cache DBCC SHOW_STATISTICS - Display the current distribution statistics DBCC SHRINKDATABASE - Shrink the size of the database data and log files. DBCC SHRINKFILE - Shrink or empty a database data or log file. DBCC SQLPERF - Display transaction-log space statistics. Reset wait and latch statistics. DBCC TRACE - Enable or Disable trace flags DBCC UPDATEUSAGE - Report and correct page and row count inaccuracies in catalog views DBCC USEROPTIONS - Return the SET options currently active DBCC deprecated commands

[http://sqltutorials.blogspot.com/2008/07/list-of-dbcc-in-sql-server-2005.html]