SQL Server CURRENT_USER() Function

The CURRENT_USER() function in SQL Server is a useful tool for identifying the currently logged-in user executing a query. This function helps track user activity and enforce security policies and is often used in auditing scenarios. In this article, We will learn about SQL Server CURRENT_USER() Function in detail.

SQL Server CURRENT_USER() Function

• The CURRENT_USER() function in SQL Server returns the name of the current user that is executing the query.
  
• It identifies the SQL Server login under which the current session is running.
  
• This function is often used to track or log the activities of the user or to enforce security measures based on user identity.

Syntax

CURRENT_USER() function syntax is:

SELECT CURRENT_USER;

The function will return the username associated with the SQL Server login for the current session.

Examples of SQL Server CURRENT_USER() Function

Let's look at a few examples of the CURRENT_USER() function in SQL Server.

Example 1:

Using CURRENT_USER () function and getting the current user’s name.

SELECT CURRENT_USER AS logged_in_user;

Output:

Here, CURRENT_USER() returns the name AdminUser, which is the identity of the user executing the query

Example 2:

Using CURRENT_USER as a default value in the below example and getting the output.

Query:

CREATE TABLE user01 (
    user_id int IDENTITY(100, 2) NOT NULL,
    customer_id int NOT NULL,
    user_name char(50) NOT NULL DEFAULT CURRENT_USER
);

INSERT INTO user01 (customer_id)
VALUES (101), (102);

Displaying the contents of the table -

SELECT * FROM user01;  

Output :

Here, firstly we need to create a table then insert values into it then generate the required output using CURRENT_USER function as a default value.

Note: For running above code use SQL server compiler, you can also use an online compiler.\

Example 3:

Using CURRENT_USER () function and impersonating user 'Geek'.

SELECT CURRENT_USER;

EXECUTE AS USER = 'Geek'; 

SELECT CURRENT_USER;   

Output :

nidhi
Geek

Here, we are impersonating user as 'Geek', then calling CURRENT_USER function to get the current user's name.

Example 4:

Using CURRENT_USER () function for impersonating user 'Geek' then again reverting the code to get the previous current user.

SELECT CURRENT_USER;  
EXECUTE AS USER = 'Geek';  
SELECT CURRENT_USER;   
REVERT;
SELECT CURRENT_USER;

Output :

nidhi
Geek
nidhi

Conclusion

The CURRENT_USER() function is an important feature in SQL Server, enabling users to determine the identity under which queries are executed. It is valuable for auditing, security, and tracking purposes, making it a frequently used function in database management. From getting the current user's name to impersonating users in a controlled environment, CURRENT_USER() serves many practical purposes in managing user sessions effectively.