I have three tables that are all inter-related with the following structure.
ModuleCategory Table:
+------------------+----------------+------------+
| ModuleCategoryID | ModuleCategory | RequireAll |
+------------------+----------------+------------+
| 90 | Cat A | YES |
| 91 | Cat B | NO |
+------------------+----------------+------------+
ModuleCategorySkill Table:
+------------------+---------+
| ModuleCategoryID | SkillID |
+------------------+---------+
| 90 | 1439 |
| 90 | 3016 |
| 91 | 1440 |
| 91 | 3016 |
+------------------+---------+
EmployeeSkill Table:
+---------+---------+
| EmpName | SkillID |
+---------+---------+
| Emp1 | 1439 |
| Emp1 | 3016 |
| Emp2 | 1440 |
| Emp2 | 3016 |
| Emp3 | 1439 |
| Emp4 | 3016 |
+---------+---------+
Desired Output:
+------------------+-------+
| ModuleCategory | Count |
+------------------+-------+
| Cat A | 1 |
| Cat B | 3 |
+------------------+-------+
I am trying to group by ModuleCategoryID's and get the count of employees which have the skills being tracked.
Normally, I can do the following query to obtain the numbers:
select mc.ModuleCategory, Count(*) as Count from ModuleCategory as mc
join ModuleCategorySkill as mcs on mc.ModuleCategoryID = mcs.ModuleCategoryID join EmployeeSkill as es on es.SkillID= mcs.SkillID
group by mc.ModuleCategoryID
However, I have a column RequireAll in the ModuleCategory table which if it is set to 'YES' should only count employees as 1 only if they have all the skills in the category. If it is set to NO then it can count each row normally and increase the count by the number of rows it groups by.
I can achieve this by writing separate queries for each modulecategoryID and using a having Count() > 1 (which will find me anyone that has all the skills for ModuleCategoryID 90). If there were 3 skills than I would have to change it to Having Count() > 2. If there isn't anyone that has all the skills specified, the count should be 0.
I need a dynamic way of being able to do this since there is a lot of data and writing one query for each ModuleCategoryID isn't the proper approach.
Also, I am using PHP so I can loop through and create a sql string that can help me achieve this. But I know I will run into performance issues on big tables with a lot of skills and modulecategoryID's.
Any guidance on how to achieve this is much appreciated.