SESSION_USER (Transact-SQL)

Artikkeli
09/03/2024

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)

SESSION_USER returns the user name of the current context in the current database.

Transact-SQL syntax conventions

Syntax

SESSION_USER

Return Types

nvarchar(128)

Remarks

Use SESSION_USER with DEFAULT constraints in either the CREATE TABLE or ALTER TABLE statements, or use it as any standard function. SESSION_USER can be inserted into a table when no default value is specified. This function takes no arguments. SESSION_USER can be used in queries.

If SESSION_USER is called after a context switch, SESSION_USER will return the user name of the impersonated context.

Examples

A. Using SESSION_USER to return the user name of the current session

The following example declares a variable as nchar, assigns the current value of SESSION_USER to that variable, and then prints the variable with a text description.

DECLARE @session_usr NCHAR(30);  
SET @session_usr = SESSION_USER;  
SELECT 'This session''s current user is: '+ @session_usr;  
GO

This is the result set when the session user is Surya:

--------------------------------------------------------------
This session's current user is: Surya

(1 row(s) affected)

B. Using SESSION_USER with DEFAULT constraints

The following example creates a table that uses SESSION_USER as a DEFAULT constraint for the name of the person who records receipt of a shipment.

USE AdventureWorks2022;  
GO  
CREATE TABLE deliveries3  
(  
 order_id INT IDENTITY(5000, 1) NOT NULL,  
 cust_id  INT NOT NULL,  
 order_date SMALLDATETIME NOT NULL DEFAULT GETDATE(),  
 delivery_date SMALLDATETIME NOT NULL DEFAULT   
    DATEADD(dd, 10, GETDATE()),  
 received_shipment NCHAR(30) NOT NULL DEFAULT SESSION_USER  
);  
GO

Records added to the table will be stamped with the user name of the current user. In this example, Wanida, Sylvester, and Alejandro verify receipt of shipments. This can be emulated by switching user context by using EXECUTE AS.

EXECUTE AS USER = 'Wanida'  
INSERT deliveries3 (cust_id)  
VALUES (7510);  
INSERT deliveries3 (cust_id)  
VALUES (7231);  
REVERT;  
EXECUTE AS USER = 'Sylvester'  
INSERT deliveries3 (cust_id)  
VALUES (7028);  
REVERT;  
EXECUTE AS USER = 'Alejandro'  
INSERT deliveries3 (cust_id)  
VALUES (7392);  
INSERT deliveries3 (cust_id)  
VALUES (7452);  
REVERT;  
GO

The following query selects all information from the deliveries3 table.

SELECT order_id AS 'Order #', cust_id AS 'Customer #',   
   delivery_date AS 'When Delivered', received_shipment   
   AS 'Received By'  
FROM deliveries3  
ORDER BY order_id;  
GO

Here's the result set.

Order #   Customer #  When Delivered       Received By
--------  ----------  -------------------  -----------
5000      7510        2005-03-16 12:02:14  Wanida
5001      7231        2005-03-16 12:02:14  Wanida
5002      7028        2005-03-16 12:02:14  Sylvester
5003      7392        2005-03-16 12:02:14  Alejandro
5004      7452        2005-03-16 12:02:14  Alejandro

(5 row(s) affected)

Examples: Azure Synapse Analytics and Analytics Platform System (PDW)

C: Using SESSION_USER to return the user name of the current session

The following example returns the session user for the current session.

SELECT SESSION_USER;

Jaa