SQL Server SESSION_USER() Function

SQL Server SESSION_USER() Function

The SQL Server SESSION_USER() function returns the name of the current user for the session. This function is useful for identifying the user connected to the SQL Server instance during the session.

Syntax

SELECT SESSION_USER;

The SESSION_USER() function does not take any arguments.

Example SQL Server SESSION_USER() Function Queries

Let's look at some examples of SQL Server SESSION_USER() function queries:

1. Basic SESSION_USER() Example

SELECT SESSION_USER AS current_user;

This query returns the name of the current user for the session. The result will be:

current_user
--------------
username

2. Using SESSION_USER() in a Table

CREATE TABLE user_actions (
    action_id INT PRIMARY KEY,
    action_description VARCHAR(255),
    user_name VARCHAR(50) DEFAULT SESSION_USER
);
INSERT INTO user_actions (action_id, action_description) VALUES (1, 'Logged In');
SELECT * FROM user_actions;

This example creates a table named user_actions with a column that defaults to the session user. The result will be:

action_id  action_description  user_name
---------  -------------------  ---------
1          Logged In            username

3. SESSION_USER() with a Variable

DECLARE @current_user VARCHAR(50);
SET @current_user = SESSION_USER;
SELECT @current_user AS current_user;

This query uses a variable to store the session user's name and then returns it. The result will be:

current_user
--------------
username

Full Example

Let's go through a complete example that includes creating a table, inserting data, and using the SESSION_USER() function.

Step 1: Creating a Table

This step involves creating a new table named logs to store some sample data with user actions.

CREATE TABLE logs (
    log_id INT PRIMARY KEY,
    log_message VARCHAR(255),
    log_user VARCHAR(50) DEFAULT SESSION_USER
);

In this example, we create a table named logs with columns for log_id, log_message, and log_user.

Step 2: Inserting Data into the Table

This step involves inserting some sample data into the logs table.

INSERT INTO logs (log_id, log_message) VALUES (1, 'User logged in');
INSERT INTO logs (log_id, log_message) VALUES (2, 'User viewed a page');
INSERT INTO logs (log_id, log_message) VALUES (3, 'User logged out');

Here, we insert data into the logs table.

Step 3: Using the SESSION_USER() Function

This step involves using the SESSION_USER() function to retrieve the current user for each log entry.

SELECT log_id, log_message, log_user
FROM logs;

This query retrieves the log_id, log_message, and log_user for each row in the logs table. The result will be:

log_id  log_message        log_user
------  -------------      --------
1       User logged in     username
2       User viewed a page username
3       User logged out    username

Conclusion

The SQL Server SESSION_USER() function is a useful tool for identifying the current user for the session in the SQL Server database. Understanding how to use the SESSION_USER() function and its syntax is essential for effective user management and data processing in SQL Server.