Search notes:

SQL Server: @@-variables

@@fetch_status

After fetching from a cursor, @@fetch_status is 0 if a record was fetched and non 0 otherwise.

See @@options

@@rowcount stores how many recores were affected or read in the most recent sql statement.

update tq84_foo set col_1 = @col_val where id = @foo_id;
if @@rowcount = 0
   print 'No rows were updated'

The Oracle equivalent for @@rowcount seems to be %rowcount.

@@servername stores the name of the server. This is the value that is needed for the -S option in sqlcmd.exe to connect to a specific instance.

Compare with serverproperty('ServerName') and @@servicename.

@@servicename returns the name of the registry key below HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server under which an instance is running.

Note: for non default services, the Windows service that runs on behalv of the instance is prefixed with MSSQL$.

For the default instance, both values, @@serivcename and the name of the Windows service are equal: MSSQLSERVER.

Compare with @@servername.

@@spid stores the current session id.

@@spid can be joined to the column spid in sys.sysprocesses.

@@trancount counts the nested transactions.

@@version returns the version of the currently installed SQL Server.