Attendance Report in MySql

Question

I want to write a query to generate attendance report of employee. First I will tell you how the presence of employee is stored in my database.

I have following tables.<

Answer 1

Here is a long way that should work as expected:

SELECT
    Employee.emp_Name,
    '2011' AS `Year`,
    'Dec' AS `Month`,
    CASE (
        IF(
            DATE('1-12-2011') < DATE(Employee.Joining_Date)),
            '0' --Not joined yet
            IF (
                (SELECT COUNT(*) FROM Holiday WHERE DATE('1-12-2011') = DATE(Holiday.date)) = 1,
                '1', --National Holiday
                IF (
                    (SELECT COUNT(*) FROM Leave WHERE DATE('1-12-2011') > DATE(Leave.to_Date) AND DATE('1-12-2011') < DATE(Leave.from_Date) AND Leave.Emp_Id = Employee.emp_id) = 1,
                    '2', --On Leave
                    IF(
                        (SELECT COUNT(*) FROM Doctor WHERE DATE('1-12-2011') > DATE(Doctor.Call_Date) AND Doctor.call_Done_By = Employee.emp_id) = 1 OR 
                        (SELECT COUNT(*) FROM Chemist WHERE DATE('1-12-2011') > DATE(Chemist.Call_Date) AND Chemist.call_Done_By = Employee.emp_id) = 1,
                        '3' --Visit Doctor or Chemist
                        '4' --Employee was at work
                    )
                )
            )
        )
    )
        WHEN 0 THEN 'N/A' --Not joined yet
        WHEN 1 THEN 'L' --National Holiday
        WHEN 2 THEN 'L' --On Leave
        WHEN 3 THEN 'S' --Visit Doctor or Chemist
        ELSE 'Y' --Employee was at work
    END AS `1`, --first day of month
    ... AS `2`, --repeat for second day of the month till max day of current month replace '1-12-2011' with each different day of month
    ...
    ... AS `30`
FROM
    Employee

My suggestion is to create a view that does the if statement for each employee that way your code will be easier to maintain. Please keep in mind that this is pseudo code that might need some some changing to run.

Hope this helps.