Can you explain what the CallableStatement interface is and in what cases it is used in working with databases?

CallableStatement is an interface in Java JDBC used to call stored procedures and functions in a database. It extends the PreparedStatement interface and allows passing parameters, as well as retrieving output parameters and return values.

Main use cases of CallableStatement:

• Calling stored procedures that perform complex logic on the database side.
• Retrieving output parameters from a procedure.
• Executing procedures with multiple parameters (input, output, and input-output).

Example of usage:

CallableStatement cs = connection.prepareCall("{call getUserName(?, ?)}");
cs.setInt(1, userId); // input parameter
cs.registerOutParameter(2, Types.VARCHAR); // output parameter
cs.execute();
String userName = cs.getString(2);

Thus, CallableStatement is convenient for integration with business logic implemented in the database.