Returning Identity Value in SQL Server: @@IDENTITY Vs SCOPE_IDENTITY Vs IDENT_CURRENT
- by Arefin Ali
We have some common misconceptions on returning the last inserted identity value from tables. To return the last inserted identity value we have options to use @@IDENTITY or SCOPE_IDENTITY or IDENT_CURRENT function depending on the requirement but it will be a real mess if anybody uses anyone of these functions without knowing exact purpose. So here I want to share my thoughts on this. @@IDENTITY, SCOPE_IDENTITY and IDENT_CURRENT are almost similar functions in terms of returning identity value. They all return values that are inserted into an identity column. Earlier in SQL Server 7 we used to use @@IDENTITY to return the last inserted identity value because those days we don’t have functions like SCOPE_IDENTITY or IDENT_CURRENT but now we have these three functions. So let’s check out which one responsible for what. IDENT_CURRENT returns the last inserted identity value in a particular table. It never depends on a connection or the scope of the insert statement. IDENT_CURRENT function takes a table name as parameter. Here is the syntax to get the last inserted identity value in a particular table using IDENT_CURRENT function. SELECT IDENT_CURRENT('Employee') Both the @@IDENTITY and SCOPE_IDENTITY return the last inserted identity value created in any table in the current session. But there is little difference between these two i.e. SCOPE_IDENTITY returns value inserted only within the current scope whereas @@IDENTITY is not limited to any particular scope. Here are the syntaxes to get the last inserted identity value using these functions SELECT @@IDENTITY SELECT SCOPE_IDENTITY() Now let’s have a look at the following example. Suppose I have two tables called Employee and EmployeeLog. CREATE TABLE Employee ( EmpId NUMERIC(18, 0) IDENTITY(1,1) NOT NULL, EmpName VARCHAR(100) NOT NULL, EmpSal FLOAT NOT NULL, DateOfJoining DATETIME NOT NULL DEFAULT(GETDATE()) ) CREATE TABLE EmployeeLog ( EmpId NUMERIC(18, 0) IDENTITY(1,1) NOT NULL, EmpName VARCHAR(100) NOT NULL, EmpSal FLOAT NOT NULL, DateOfJoining DATETIME NOT NULL DEFAULT(GETDATE()) ) I have an insert trigger defined on the table Employee which inserts a new record in the EmployeeLog whenever a record insert in the Employee table. So Suppose I insert a new record in the Employee table using following statement: INSERT INTO Employee (EmpName,EmpSal) VALUES ('Arefin','1') The trigger will be fired automatically and insert a record in EmployeeLog. Here the scope of the insert statement and the trigger are different. In this situation if I retrieve last inserted identity value using @@IDENTITY, it will simply return the identity value from the EmployeeLog because it’s not limited to a particular scope. Now if I want to get the Employee table’s identity value then I need to use SCOPE_IDENTITY in this scenario. So the moral is always use SCOPE_IDENTITY to return the identity value of a recently created record in a sql statement or stored procedure. It’s safe and ensures bug free code.
