How to Choose the Best Method for Retrieving the Last Inserted Identity Value?

Retrieving Last Identity: Comparing Methods

When retrieving the identity value of a primary key after insert, multiple methods are available. This article explores the advantages and limitations of each method to help you choose the most suitable one for your needs.

Overview of Methods

The following methods are commonly used:

• @@IDENTITY: Returns the last identity value generated for any table on the current connection.
• SCOPE_IDENTITY(): Returns the last identity value generated within the current scope, regardless of the table.
• OUTPUT Clause: Returns a table of all identity values generated by an insert statement.
• IDENT_CURRENT('Table'): Returns the last identity value generated for a specific table.

Method Comparison

@@IDENTITY is not scope-safe, as it can return the identity value generated by a different statement or trigger. SCOPE_IDENTITY() is scope-safe but returns the last identity value generated regardless of the table, which can be confusing in some cases.

The OUTPUT clause is advantageous for retrieving multiple identity values or additional columns, but it requires explicitly specifying which columns to return. IDENT_CURRENT('Table') is useful when you need to retrieve the identity value only for a specific table.

Scope-Safety Considerations

The OUTPUT clause is not scope-safe, as it returns a table rather than a single value. Therefore, it cannot be used in contexts where a single identity value is expected, such as when setting a primary key value in a foreign key relationship.

Conclusion

The choice of method depends on the specific requirements of your application. For scoped identity values, SCOPE_IDENTITY() is recommended; for non-scoped identity values or when retrieving multiple identity values, OUTPUT can be useful; and for retrieving identity values for a specific table, IDENT_CURRENT('Table') is suitable.

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