SQL USER

What is the SQL USER keyword?

Returns the name of the database user currently connected to the session.

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Compatible dialects for SQL USER: PostgreSQL, MySQL, SQL Server, Oracle, SQLite

SQL USER Full Explanation

USER is a scalar SQL function/keyword that yields the identifier of the account under which the current session is running. It is frequently used for auditing, row-level security, and conditional logic. Depending on the DBMS, USER may be a reserved word (Oracle, PostgreSQL) or a built-in function that can be invoked with or without parentheses (MySQL, SQL Server). In Standard SQL it is synonymous with CURRENT_USER, but some systems make minor distinctions: SESSION_USER follows initial logon credentials while USER/CURRENT_USER may change after SET ROLE or SET SESSION AUTHORIZATION. USER never requires arguments and returns a string (or database identifier) typed as VARCHAR or identifier, limited by the maximum username length of the given system.

SQL USER Syntax

-- Standard form
SELECT USER;

-- Callable form (vendor specific)
SELECT USER();

SQL USER Parameters

Example Queries Using SQL USER

-- Show current user in a troubleshooting session
SELECT USER;

-- Insert audit trail with acting user
INSERT INTO audit_log(event_time, actor, action)
VALUES (CURRENT_TIMESTAMP, USER, 'deleted record');

-- Conditional logic based on user
SELECT CASE WHEN USER = 'admin' THEN 'full' ELSE 'limited' END AS access_level;

Expected Output Using SQL USER

Each query returns a single string column containing the username of the session (e
g
, "alice" or "alice@localhost" in MySQL)

Use Cases with SQL USER

Record the actor in audit tables
Enforce row-level security policies
Display connection diagnostics in client apps
Build conditional branches in stored procedures depending on the invoker

Common Mistakes with SQL USER

Confusing USER with SESSION_USER or SYSTEM_USER, which may differ after role changes
Adding arguments (e.g., USER('alice')) – USER takes none
Forgetting parentheses in DBMSs that require them (MySQL USER()) or adding them where they are not allowed (Oracle USER())
Expecting the host portion in PostgreSQL/Oracle, which only return the username (MySQL includes host)

First Introduced In

SQL-92 Standard

Frequently Asked Questions

What does USER return?

It returns the username under which the current SQL session is executing, usually a VARCHAR.

How is USER different from SESSION_USER?

SESSION_USER remains fixed to the login identity, while USER/CURRENT_USER may change after SET ROLE or similar statements.

Do I need parentheses after USER?

Oracle and PostgreSQL: no. MySQL and SQL Server: yes (USER()).

Can I use USER in a WHERE clause?

Yes. For example: `SELECT * FROM orders WHERE created_by = USER;`