Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

Chapter 11: Writing Scripts and Batches
330
Variable Purpose Comments
@@REMSERVER Used only in stored
procedures. Returns
the value of the
server that called the
stored procedure.
@@ROWCOUNT One of the most
used system functions.
Returns the
number of rows
affected by the last
statement.
SCOPE_IDENTITY Similar to @@IDEN-
TITY, but returns the
last identity inserted
within the current
session and scope.
@@SERVERNAME Returns the name
of the local server
that the script is
running from.
@@TRANCOUNT Returns the number
of active transactions
— essentially
the transaction nesting
level — for the
current connection.
@@VERSION Returns the current
version of SQL
Server as well as the
date, processor, and
O/S architecture.
Handy when you want the sproc to behave differently
depending on the remote server (often a
geographic location) from which it was called.
Still, in this era of .NET, I would question
whether anything needing this variable might
have been better written using other functionality
found in .NET.
Commonly used in non runtime error checking.
For example, if you try to DELETE a row using a
WHERE clause, and no rows are affected, then that
would imply that something unexpected happened.
You can then raise an error manually.
Very useful for avoiding issues where a trigger or
nested stored procedure has performed additional
inserts that have overwritten your
expected identity value.
Can be changed by using sp_addserver and
then restarting SQL Server, but rarely required.
A ROLLBACK TRAN statement decrements
@@TRANCOUNT to 0 unless you are using save
points. BEGIN TRAN increments @@TRANCOUNT by
1, COMMIT TRAN decrements @@TRANCOUNT by 1.
Unfortunately, this doesn’t return the information
into any kind of structured field arrangement, so
you have to parse it if you want to use it to test
for specific information. Also be sure to check out
the xp_msver extended stored procedure.
Don’t worry if you don’t recognize some of the terms in a few of these. They will become clear in due
time, and you will have this table or Appendix A to look back on for reference at a later date. The thing
to remember is that there are sources you can go to in order to find out a whole host of information
about the current state of your system and your activities.