在使用左外连接的 SQL 查询中需要帮助

Question

I am trying to get the employee's details who have taken leaves and who haven't taken leaves using the below query, but it is not returning the employee's names who have not taken any leaves.

Any help would be appreciated.

SELECT distinct paf.employee_number,PAF.FULL_NAME,aba.absence_attendance_type_id
           FROM 
                per_all_assignments_f ass,
                per_all_people_f paf,
                per_absence_attendances aba
          WHERE     1 = 1
          AND ass.assignment_number  = paf.employee_number
          
                AND aba.person_id(+) = ass.person_id
                AND aba.absence_attendance_type_id =28074
                AND ass.business_group_id = 134
                AND TRUNC (SYSDATE) BETWEEN TRUNC (ass.effective_start_date)
                                        AND TRUNC (ass.effective_end_date)
                AND TRUNC (SYSDATE) BETWEEN TRUNC (paf.effective_start_date)
                                        AND  nvl(paf.effective_end_date, trunc(sysdate))    
                and paf.current_employee_flag = 'Y'
                order by paf.employee_number;

Answer 1

Please try this:

SELECT distinct paf.employee_number,PAF.FULL_NAME,aba.absence_attendance_type_id
       FROM 
            per_all_assignments_f ass 
            inner join per_all_people_f paf on ass.assignment_number  = paf.employee_number
            Left Join per_absence_attendances aba on aba.person_id = ass.person_id
            and aba.absence_attendance_type_id =28074
      WHERE               
            ass.business_group_id = 134
            AND TRUNC (SYSDATE) BETWEEN TRUNC (ass.effective_start_date)
                                    AND TRUNC (ass.effective_end_date)
            AND TRUNC (SYSDATE) BETWEEN TRUNC (paf.effective_start_date)
                                    AND  nvl(paf.effective_end_date, trunc(sysdate))    
            and paf.current_employee_flag = 'Y'
            order by paf.employee_number;

Answer 2

Thanks for helping me..

I have used below query to get all the employee's name

SELECT distinct paf.employee_number,PAF.FULL_NAME,aba.absence_attendance_type_id
       FROM 
            per_all_assignments_f ass,
            per_all_people_f paf,
            per_absence_attendances aba
      WHERE     1 = 1
      AND ass.assignment_number  = paf.employee_number
      
            AND aba.person_id(+) = ass.person_id
            AND aba.absence_attendance_type_id (+)= 28074
            AND ass.business_group_id = 134
            AND TRUNC (SYSDATE) BETWEEN TRUNC (ass.effective_start_date)
                                    AND TRUNC (ass.effective_end_date)
            AND TRUNC (SYSDATE) BETWEEN TRUNC (paf.effective_start_date)
                                    AND  nvl(paf.effective_end_date, trunc(sysdate))    
            and paf.current_employee_flag = 'Y'
            order by paf.employee_number;

Adding (+) in this line "aba.absence_attendance_type_id (+)= 28074" worked for me.

And the query provided by @Kazi Mohammad Ali Nur is also working. Thank you again. Now I understood the issue and the use of left outer join specially when multiple conditions are required to filter the data.

Sample Output:

Emp no	Name	Attendence Id
1	John	123
2	Poly	123
3	Sopra
4	Cali	123