To be able to execute SQL statements in a database instance, you have to have opened a database session.
To open a database session, log on to a database instance as a database user with a user name and password, using either a database tool or an interface. When you open a database session, you can override some properties, including the following:
? SQL mode
? Cache limit
? Timeout value
? Isolation level
Later, you terminate the database session with the corresponding command, or the database system terminates the database session when the timeout value is exceeded.
The database system starts a user task for each database session. You can configure the maximum number of user tasks, and thereby the maximum number of database sessions, by using the MAXUSERTASKS general database parameter.
When configuring these database parameters, please note that database tools open and close database sessions implicitly for specific actions.
SQL Studio, Opening a Database Session
Web SQL Studio, Logging on to a Database Instance
Database Manager GUI, Displaying Database Sessions
Database Manager CLI, SQL Access to the Database Instance
Concepts of the Database System, General Database Parameters