Вы можете изменить свой запрос следующим образом:
SELECT u.employee_id AS Employee_ID, u.user_name AS UserName,
COALESCE(pd.ctd_name, pp.ctd_name) AS PrimaryDeptOrProj,
r.region_name AS Region, ct.ctd_id, ct.ctd_name, SUM(tsdd.workhours)
FROM users u
LEFT JOIN category_type_details pd ON u.user_primary_department = pd.ctd_id
LEFT JOIN category_type_details pp ON u.user_primary_project = pp.ctd_id
LEFT JOIN regions r ON u.region_id = r.region_id
LEFT JOIN timesheets ts ON u.user_id = ts.timesheet_user
INNER JOIN timesheet_mr tsmr ON ts.timesheet_caller = tsmr.tsmr_id AND tsmr.tsmr_id = 14
INNER JOIN timesheet_details tsd ON ts.timesheet_id = tsd.tsd_timesheet_id
INNER JOIN timesheet_day_details tsdd ON tsd.tsd_id = tsdd.tsd_id
RIGHT OUTER JOIN category_type_details ct ON tsd.tsd_category_type_id = ct.ctd_id AND u.employee_id = "0079-P"
GROUP BY ct.ctd_id, u.user_id, u.employee_id, u.user_name,
COALESCE(pd.ctd_name, pp.ctd_name), r.region_name, ct.ctd_name
ORDER BY ct.ctd_id, u.user_id, u.employee_id, u.user_name,
COALESCE(pd.ctd_name, pp.ctd_name), r.region_name, ct.ctd_name;
Вы получили только 1 строку, поскольку условие в предложении WHERE
фильтрует все строки NULL
user_id для другой категории.
Для MySQL
вы можете опустить другие столбцы в предложении GROUP BY
:
SELECT u.employee_id AS Employee_ID, u.user_name AS UserName,
COALESCE(pd.ctd_name, pp.ctd_name) AS PrimaryDeptOrProj,
r.region_name AS Region, ct.ctd_id, ct.ctd_name, SUM(tsdd.workhours)
FROM users u
LEFT JOIN category_type_details pd ON u.user_primary_department = pd.ctd_id
LEFT JOIN category_type_details pp ON u.user_primary_project = pp.ctd_id
LEFT JOIN regions r ON u.region_id = r.region_id
LEFT JOIN timesheets ts ON u.user_id = ts.timesheet_user
INNER JOIN timesheet_mr tsmr ON ts.timesheet_caller = tsmr.tsmr_id AND tsmr.tsmr_id = 14
INNER JOIN timesheet_details tsd ON ts.timesheet_id = tsd.tsd_timesheet_id
INNER JOIN timesheet_day_details tsdd ON tsd.tsd_id = tsdd.tsd_id
RIGHT OUTER JOIN category_type_details ct ON tsd.tsd_category_type_id = ct.ctd_id AND u.employee_id = "0079-P"
GROUP BY ct.ctd_id, u.user_id
ORDER BY ct.ctd_id, u.user_id;