Generic query for multicriteria search - part I: USE_CONCAT (OR Expansion)

You have a multicriteria search screen on the EMPLOYEE table where you can enter an employee id, a department id, a manager id or a job id. Either you put the value you want to filter on, or you leave it null when you don't want to filter on it. How will you code that? You can build the query on the fly with dynamic SQL or use a generic query like this one:

       SELECT *
       FROM employees
       WHERE (job_id = NVL(:job_id, job_id))
       AND (department_id = NVL(:department_id, department_id))
       AND (manager_id = NVL(:manager_id, manager_id))
       AND (employee_id = NVL(:employee_id, employee_id))

This is good for the code maintainability, but having a one-fit-all query will not be optimial for each cases. Markus Winand (every database developer should read his book) describes the danger ot that in his website: Use The Index, Luke