Thursday, October 27, 2011

GO - Batch Separator

GO is not a SQL Statement or SQL Command. It is just a Batch Separator used by SQL Client tools like SQL Server Management Studio, SQL CMD etc.,

Extract from MSDN

"GO is not a Transact-SQL statement; it is a command recognized by the sqlcmd and osql utilities and SQL Server Management Studio Code editor.
SQL Server utilities interpret GO as a signal that they should send the current batch of Transact-SQL statements to an instance of SQL Server. The current batch of statements is composed of all statements entered since the last GO, or since the start of the ad hoc session or script if this is the first GO."

In SSMS:

Though the default Batch Separator is GO we can change it as well! Just go to Tools > Options >Query Execution > SQL Server > General > Batch Separator.



Let's change our Batch Separator as "Done". Please note that it would take effect only from the next SQL Query window which we open. We can't use it directly in any of the already opened Query windows.



In a new query window lets try to use our Batch Separator "Done" to see it working.



In my personal experience changing the Batch Separator is fun as long as we do it in our local boxes or to confuse our friends :) 

I would strongly suggest we stick with the default Batch Separator GO while generating scripts for deployment (or) sharing with other developers. Reason being, if we generate the scripts with this new Batch Separator "Done" then the place where it is run would throw up errors! Because the destination box still has the Batch Separator as 'GO'.

Now lets revert the batch separator to 'GO' and then try the same script. If you had expected an error to be thrown you would be surprised!


It has taken 'DONE' as an Alias name :)

This is one another good reason to use proper alias names ourself in the scripts. Now if we add an alias name ourself and check the same script it would throw the syntax error as expected.



Apart from this since SQL Server 2005 onwards we can use a positive integer value after GO and make that batch to execute that many times. I have used this many times in my previous posts. If you are looking for an working example check out this.


In SQLCMD:


Lets use the same example of printing the current datetime using SQLCMD utility. Goto Command prompt and type SQLCMD. Check out the below screenshot where I have connected using Windows Authentication and used a batch separator for printing current datetime.


Now if we need to change the Batch Separator for this utility as well then we need to make use of -c for it as shown in the below screenshot.


The Batch Separator 'Done' will work only as long as this current connection is open. If you close this command prompt and reopen it again you could see that it has gone back to the default batch separator 'GO'.

To know complete list of options for SQLCMD check out this MSDN article.

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