MySQL provides various information functions that allow you to retrieve details about the database server, user sessions, and other relevant information. Here’s an overview of some of the key information functions:
| Function | Description |
|---|---|
| CONNECTION_ID() | Returns the unique connection identifier for the current session. Useful for identifying different connections in a multi-user environment. |
| CURRENT_ROLE() | Returns the current active role for the user in the current session. Roles are used for managing user privileges and permissions. |
| CURRENT_USER() | Returns the username and hostname of the MySQL account that the MySQL server uses to authenticate the current client. This function can be used to identify the current user, which can be helpful for troubleshooting purposes. |
| DATABASE() | Returns the current database name as a string. This function can be used to determine the current database that the user is working in. |
| SCHEMA() | Synonym for DATABASE(). |
| USER() | Returns the username and hostname of the current MySQL account. This function is a synonym for CURRENT_USER() and can be used interchangeably with that function. |
| SESSION_USER() | Synonym for USER(). Returns the user name and host name for the MySQL account used to establish the current session. |
| SYSTEM_USER() | Synonym for USER(). Returns the operating system user name under which the MySQL server is executing. |
| VERSION() | Returns the version of the MySQL server. |
These information functions can be useful for monitoring and logging activities, as well as for dynamic query generation based on the current context of the database server or user session. Keep in mind that the availability of certain functions might depend on the MySQL server version, and some functions might require specific privileges for execution. Always refer to the MySQL documentation for detailed and version-specific information.