Question

I am doing a formula to make some statistics in SQL, but I do not know how to improve a query I am working on…

I made a sqlfiddle so you can understand me better

So I have 3 tables and I need to solve a formula varying the indexes, i,j…

i j
---
1 1
1 2
1 3
2 1
2 2
2 3
3 1
3 2
3 3

and then do some sqrt and pow. I want the result in a table but I do not know how to generalize all those long queries into one…

Answer 1

This appears to just need a couple of CROSS JOINs:

SELECT  ((N.n*M1.m)-(S1.s*S2.s)) / 
               (SQRT((N.n*M2.m)-(pow(S1.s,2))) * SQRT((N.n*M3.m)-(pow(S2.s,2))))
FROM N
CROSS JOIN sums as S1
CROSS JOIN sums as S2
JOIN mults as M1
     ON M1.i = S1.i
     AND M1.j = S2.i
JOIN mults as M2
     ON M2.i = S1.i
     AND M2.j = S1.i
JOIN mults as M3
     ON M3.i = S2.i
     AND M3.j = S2.i;

(I’ve modified the Fiddle to include this. Thanks for providing one!).

However, your overall design is a little suspicious to me; what exactly are you attempting to accomplish?