Question

I want to subtract between two rows of different table:

I have created a view called leave_taken and table called leave_balance.

I want this result from both table:

leave_taken.COUNT(*) - leave_balance.balance

and group by leave_type_id_leave_type

Code of both table

—————–View Leave_Taken———–

CREATE ALGORITHM = UNDEFINED DEFINER=`1`@`localhost` SQL SECURITY DEFINER 
VIEW `leave_taken` 
AS 
   select 
     `leave`.`staff_leave_application_staff_id_staff` AS `staff_leave_application_staff_id_staff`,
     `leave`.`leave_type_id_leave_type` AS `leave_type_id_leave_type`,
     count(0) AS `COUNT(*)` 
   from 
   (
      `leave` 
      join `staff` on((`staff`.`id_staff` = `leave`.`staff_leave_application_staff_id_staff`))
   ) 
   where (`leave`.`active` = 1) 
   group by `leave`.`leave_type_id_leave_type`;

—————-Table leave_balance———-

CREATE TABLE IF NOT EXISTS `leave_balance` (
  `id_leave_balance` int(11) NOT NULL AUTO_INCREMENT,
  `staff_id_staff` int(11) NOT NULL,
  `leave_type_id_leave_type` int(11) NOT NULL,
  `balance` int(3) NOT NULL,
  `date_added` date NOT NULL,
  PRIMARY KEY (`id_leave_balance`),
  UNIQUE KEY `id_leave_balance_UNIQUE` (`id_leave_balance`),
  KEY `fk_leave_balance_staff1` (`staff_id_staff`),
  KEY `fk_leave_balance_leave_type1` (`leave_type_id_leave_type`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;

——- Table leave ———-

CREATE TABLE IF NOT EXISTS `leave` (
  `id_leave` int(11) NOT NULL AUTO_INCREMENT,
  `staff_leave_application_id_staff_leave_application` int(11) NOT NULL,
  `staff_leave_application_staff_id_staff` int(11) NOT NULL,
  `leave_type_id_leave_type` int(11) NOT NULL,
  `date` date NOT NULL,
  `active` int(11) NOT NULL DEFAULT '1',
  `date_updated` date NOT NULL,
  PRIMARY KEY (`id_leave`,`staff_leave_application_id_staff_leave_application`,`staff_leave_application_staff_id_staff`),
  KEY `fk_table1_leave_type1` (`leave_type_id_leave_type`),
  KEY `fk_table1_staff_leave_application1` (`staff_leave_application_id_staff_leave_application`,`staff_leave_application_staff_id_staff`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=32 ;

Answer 1

Well, I still don’t think you’ve provided enough information. It would be very helpful to have some sample data and your expected output (in tabular format). That said, I may have something you can start working with. This query finds all staff members, calculates their current leave (grouped by type), and determines the difference between that and their balance by leave type. Take a look at it, and more importantly (perhaps) the sqlfiddle here that I used which has the sample data in it (very important to determining if this is the correct path for your data).

SELECT
    staff.id_staff,
    staff.name,
    COUNT(`leave`.id_leave) AS leave_count,
    leave_balance.balance,
    (COUNT(`leave`.id_leave) - leave_balance.balance) AS leave_difference,
    `leave`.leave_type_id_leave_type AS leave_type
  FROM
    staff
    JOIN `leave` ON staff.id_staff = `leave`.staff_leave_application_staff_id_staff
    JOIN leave_balance ON
      (
        staff.id_staff = leave_balance.staff_id_staff
        AND `leave`.leave_type_id_leave_type = leave_balance.leave_type_id_leave_type
      )
  WHERE 
    `leave`.active = 1
  GROUP BY
    staff.id_staff, leave_type;

Good luck!