Beginning Microsoft SQL Server 2008 ... - S3 Tech Training
Beginning Microsoft SQL Server 2008 ... - S3 Tech Training Beginning Microsoft SQL Server 2008 ... - S3 Tech Training
Appendix A: System Functions HOST_ID The HOST_ID function returns the ID of the workstation. The syntax is as follows: HOST_ID() HOST_NAME The HOST_NAME function returns the name of the workstation. The syntax is as follows: HOST_NAME() IDENT_CURRENT The IDENT_CURRENT function returns the last identity value created for a table, within any session or scope of that table. This is exactly like @@IDENTITY and SCOPE_IDENTITY; however, this has no limit to the scope of its search to return the value. The syntax is as follows: IDENT_CURRENT(‘’) The table_name is the table for which you wish to find the current identity. IDENT_INCR The IDENT_INCR function returns the increment value specified during the creation of an identity column in a table or view that has an identity column. The syntax is as follows: IDENT_INCR(‘’) The table_or_view parameter is an expression specifying the table or view to check for a valid identity increment value. IDENT_SEED The IDENT_SEED function returns the seed value specified during the creation of an identity column in a table or a view that has an identity column. The syntax is as follows: IDENT_SEED(‘’) The table_or_view parameter is an expression specifying the table or view to check for a valid identity increment value. @@IDENTITY 642 Returns the last identity value created by the current connection.
If you’re using identity columns and then referencing them as a foreign key in another table, you’ll find yourself using this one all the time. You can create the parent record (usually the one with the identity you need to retrieve), then select @@IDENTITY to know what value you need to relate child records to. If you perform inserts into multiple tables with identity values, remember that the value in @@IDENTITY will only be for the last identity value inserted — anything before that will have been lost, unless you move the value into a holding variable after each insert. Also, if the last column you inserted into didn’t have an identity column, then @@IDENTITY will be set to NULL. IDENTITY The IDENTITY function is used to insert an identity column into a new table. It is used only with a SELECT statement with an INTO table clause. The syntax is as follows: Where: ISNULL IDENTITY([, , ]) AS ❑ data type is the data type of the identity column. ❑ seed is the value to be assigned to the first row in the table. Each subsequent row is assigned the next identity value, which is equal to the last IDENTITY value plus the increment value. If neither seed nor increment is specified, both default to 1. ❑ increment is the increment to add to the seed value for successive rows in the table. ❑ column name is the name of the column that is to be inserted into the new table. The ISNULL function checks an expression for a NULL value and replaces it with a specified replacement value. The syntax is as follows: ISNULL(, ) ISNUMERIC The ISNUMERIC function determines whether an expression is a valid numeric type. The syntax is as follows: NEWID ISNUMERIC() The NEWID function creates a unique value of type uniqueidentifier. The syntax is as follows: NEWID() Apendix A: System Functions 643
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Appendix A: System Functions<br />
HOST_ID<br />
The HOST_ID function returns the ID of the workstation. The syntax is as follows:<br />
HOST_ID()<br />
HOST_NAME<br />
The HOST_NAME function returns the name of the workstation. The syntax is as follows:<br />
HOST_NAME()<br />
IDENT_CURRENT<br />
The IDENT_CURRENT function returns the last identity value created for a table, within any session or<br />
scope of that table. This is exactly like @@IDENTITY and SCOPE_IDENTITY; however, this has no limit to<br />
the scope of its search to return the value.<br />
The syntax is as follows:<br />
IDENT_CURRENT(‘’)<br />
The table_name is the table for which you wish to find the current identity.<br />
IDENT_INCR<br />
The IDENT_INCR function returns the increment value specified during the creation of an identity column<br />
in a table or view that has an identity column. The syntax is as follows:<br />
IDENT_INCR(‘’)<br />
The table_or_view parameter is an expression specifying the table or view to check for a valid identity<br />
increment value.<br />
IDENT_SEED<br />
The IDENT_SEED function returns the seed value specified during the creation of an identity column in a<br />
table or a view that has an identity column. The syntax is as follows:<br />
IDENT_SEED(‘’)<br />
The table_or_view parameter is an expression specifying the table or view to check for a valid identity<br />
increment value.<br />
@@IDENTITY<br />
642<br />
Returns the last identity value created by the current connection.
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