Question

Suppose I have table Tab (id,, DeptName, Total, ...)

There are 4 possible values for Deptname: Dept1, Dept2, Dept3, Dept4.

Then I can issue SQL for grouping like this:

Select DeptName, Totaol = Sum(total) 
from Tab 
group by DeptName

Normally, the result is will have 4 rows based on the value of DeptName:

DeptName Total
Dept1    1234.09
Dept2    234.80
Dept3    34.34
Dept4    614.48

If there is no data for Dept2, the result will only has 3 rows:

Dept1    1234.09
Dept3    34.34
Dept4    614.48

What I want is the result always has 4 rows. If there is no data for Dept2, I want the result like:

Dept1    1234.09
Dept2    0
Dept3    34.34
Dept4    614.48

How to implement this request?

Answer 1

This seems right SQL Fiddle:

SELECT t2.DeptName, Total = COALESCE(Sum(total),0)
FROM Tab t1
RIGHT OUTER JOIN (SELECT 'Dept1' as DeptName UNION ALL
                  SELECT 'Dept2' UNION ALL
                  SELECT 'Dept3' UNION ALL
                  SELECT 'Dept4') t2 ON t2.DeptName = t1.DeptName
GROUP BY t2.DeptName