When working with SQL Server, it is common to have tables with identity columns that automatically generate unique values for each new row. These identity values are useful for various purposes, such as maintaining data integrity and referencing related records. In this article, we will explore three different functions in SQL Server that can be used to retrieve the last identity value generated.

@@IDENTITY

The first function we will discuss is @@IDENTITY. This function returns the last identity value produced on a connection, regardless of the table that produced the value, and regardless of the scope of the statement that produced the value. It is important to note that @@IDENTITY is limited to the current session, but not limited to the current scope. This means that if you have a trigger on a table that causes an identity to be created in another table, @@IDENTITY will return the identity that was created last, even if it was the trigger that created it.

SCOPE_IDENTITY()

The second function we will explore is SCOPE_IDENTITY(). This function also returns the last identity value produced on a connection, but it is limited to the current scope. This means that it will return the last identity value that you explicitly created, rather than any identity that was created by a trigger or a user-defined function. SCOPE_IDENTITY() is useful when you want to retrieve the identity value generated within the same scope as your statement.

IDENT_CURRENT(‘tablename’)

The third function we will look at is IDENT_CURRENT('tablename'). This function returns the last identity value produced in a specific table, regardless of the connection that created the value or the scope of the statement that produced the value. Unlike the previous two functions, IDENT_CURRENT is not limited by scope and session; it is limited to a specified table. This function is particularly useful when you need to retrieve the identity value generated for a specific table in any session and any scope.

It is important to choose the appropriate function based on your specific requirements. If you want to retrieve the last identity value regardless of the table or scope, @@IDENTITY is the right choice. If you want to limit the retrieval to the current scope, SCOPE_IDENTITY() is the function to use. And if you need to retrieve the identity value for a specific table, IDENT_CURRENT('tablename') is the function you should use.

In conclusion, understanding SQL Server identity values and how to retrieve them is crucial when working with databases. By using the appropriate function, you can ensure accurate retrieval of the last identity value generated, based on your specific requirements.