Вот ваш запрос. переместите AND tbl_overtime_paid.status = 0
в left join
. добавление этого в where
предложение будет фильтровать все на основе этого критерия
SELECT DISTINCT tbl_user.firstname,
tbl_user.middlename,
tbl_user.lastname,
tbl_user.name_ext,
sum(coalesce(tbl_overtime_paid.amount_paid,0)),
sum(coalesce(t1.salary,0)),
sum(coalesce(t1.salary,0)+coalesce(tbl_overtime_paid.amount_paid,0))
FROM tbl_user
INNER JOIN
(SELECT sum(salary) as salary, employee_id from tbl_salary_daily
WHERE `status` = 0
group by employee_id) as t1 on tbl_user.employee_id = t1.employee_id
LEFT JOIN tbl_overtime_paid ON tbl_overtime_paid.employee_id = t1.employee_id AND tbl_overtime_paid.`status` = 0
GROUP BY tbl_user.firstname,
tbl_user.middlename,
tbl_user.lastname,
tbl_user.name_ext