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

When the editing tool encounters a GO statement, it sees it as a flag to terminate that batch, package it
up, and send it as a single unit to the server — without including the GO. That’s right, the server itself has
absolutely no idea what GO is supposed to mean.
If you try to execute a GO command in a pass-through query using ODBC, OLE DB, ADO, ADO.NET,
SqlNativeClient, or any other access method, you’ll get an error message back from the server. The GO is merely
an indicator to the tool that it is time to end the current batch, and time, if appropriate, to start a new one.
Errors in Batches
Errors in batches fall into two categories:
❑ Syntax errors
❑ Runtime errors
If the query parser finds a syntax error, processing of that batch is cancelled immediately. Since syntax
checking happens before the batch is compiled or executed, a failure during the syntax check means
none of the batch will be executed — regardless of the position of the syntax error within the batch.
Runtime errors work quite a bit differently. Any statement that has already executed before the runtime
error was encountered is already done, so anything that statement did will remain intact unless it is part
of an uncommitted transaction. (Transactions are covered in Chapter 14, but the relevance here is that
they imply an all or nothing situation.) What happens beyond the point of the runtime error depends on
the nature of the error. Generally speaking, runtime errors terminate execution of the batch from the
point where the error occurred to the end of the batch. Some runtime errors, such as a referentialintegrity
violation, will only prevent the offending statement from executing — all other statements in
the batch will still be executed. This later scenario is why error checking is so important — we will cover
error checking in full in our chapter on stored procedures (Chapter 12).
When to Use Batches
Batches have several purposes, but they all have one thing in common — they are used when something
has to happen either before or separately from everything else in your script.
Statements That Require Their Own Batch
There are several commands that absolutely must be part of their own batch. These include:
❑ CREATE DEFAULT
❑ CREATE PROCEDURE
❑ CREATE RULE
❑ CREATE TRIGGER
❑ CREATE VIEW
Chapter 11: Writing Scripts and Batches
If you want to combine any of these statements with other statements in a single script, then you will
need to break them up into their own batch by using a GO statement.
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