Question

I want to extract information from three tables which are linked by certain ids to each other. Can you please suggest me how can i do that. I tried but three tables is bit too complex. Here is what i am trying to do:

So basically from above three tables i want to match USER against respective PID showing the count of only specific SPEC type, e.g ROUND as shown in the example. (It can also happen that same PID is assinged to two different users like PID=1 for user AAA & BBB).

Can you please tell me how to go about it?

Answer 1

SELECT 
  t1.USER, 
  t1.PID, 
  COUNT(T3.SPEC) AS CountRound
FROM Table1 t1
  LEFT JOIN Table2 t2 ON t1.PID = t2.PID 
  LEFT JOIN Table3 t3 ON t2.LID = t3.LID AND t3.SPEC = 'ROUND'
GROUP BY
  t1.USER,
  t1.PID