Question

I have some data from an evaluation. Possible values are (1,2,3,4,5) and are stored in a table, for each question 1 column.

Table evaluation:

f1 f2 q3 ...
1  5  2
2  4  3
.
.
.

I want to generate for 2 columns 1 matrix:

How often is f1=1 when q3=1?
How often is f1=1 when q3=2?
...
How often is f1=5 when q3=5?

So it will be in my case a 5*5 matrix.
How can I solve this with mysql properly?

My first (working) attempt is to brute force it with 25 unions like:

SELECT count(0) FROM evaluation where q3 = 1 and f2 = 1
union all
SELECT count(0) FROM evaluation where q3 = 1 and f2 = 2
union all
...
union all
SELECT count(0) FROM evaluation where q3 = 5 and f2 = 5

But how can it be done in a nice way?

Answer 1

SELECT f1, count(f1), f3
FROM evaluation
GROUP BY f3, f1

would give you the f1 counts for all values of f3.