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

DATALENGTH
The DATALENGTH function returns the number of bytes used to represent expression as an integer. It is
especially useful with varchar, varbinary, text, image, nvarchar, and ntext data types because
these data types can store variable-length data. The syntax is as follows:
DATALENGTH()
@@ERROR
Returns the error code for the last T-SQL statement that ran on the current connection. If there is no
error, then the value will be zero.
If you’re going to be writing stored procedures or triggers, this is a bread-and-butter kind of system
function — you pretty much can’t live without it.
The thing to remember with @@ERROR is that its lifespan is just one statement. This means that, if you
want to use it to check for an error after a given statement, then you either need to make your test the
very next statement, or you need to move it into a holding variable. In general, I recommend using
ERROR_NUMBER() in a TRY…CATCH block unless you need to support pre-SQL Server 2005 code.
A listing of all the system errors can be viewed by using the sys.messages system table in the master
database.
To create your own custom errors, use sp_addmessage.
FORMATMESSAGE
The FORMATMESSAGE function uses existing messages in sysmessages to construct a message. The
syntax is as follows:
FORMATMESSAGE(, [,...n])
Where msg_number is the ID of the message in sysmessages.
FORMATMESSAGE looks up the message in the current language of the user. If there is no localized version
of the message, the U.S. English version is used.
GETANSINULL
The GETANSINULL function returns the default nullability for a database as an integer. The syntax is as
follows:
GETANSINULL([‘’])
Apendix A: System Functions
The database parameter is the name of the database for which to return nullability information.
When the nullability of the given database allows NULL values and the column or data type nullability is
not explicitly defined, GETANSINULL returns 1. This is the ANSI NULL default.
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