The CONNECTION_ID() function returns the unique connection ID for the current connection to the MySQL server. This ID is useful for identifying the connection in use by a specific query or session.
Syntax
CONNECTION_ID()
Parameters
- This function does not take any parameters.
Definition and Usage
- The
CONNECTION_ID()function returns a unique identifier (a numeric value) that corresponds to the current session or connection. - This value is automatically generated by the MySQL server when a connection is established.
Technical Details
- Works in: From MySQL 4.0.
- Return Type: An integer representing the unique connection ID for the current connection.
Example Usage
Example 1: Return the Current Connection ID
SELECT CONNECTION_ID();
This query will return the unique connection ID for the current MySQL session.
Example 2: Using CONNECTION_ID() in a Query
If you're monitoring or debugging, you can use the connection ID to track queries executed by specific sessions:
SELECT CONNECTION_ID(), User(), NOW();
This query returns the connection ID, the current user, and the current timestamp for the session.
Use Cases
- Connection Tracking: Useful for identifying and monitoring active connections to the database.
- Session Management: Can be used in logs or debugging to track the actions of specific sessions.