Question

I have a table that looks somewhat like this:

id  value
1   0
1   1
1   2
1   0
1   1
2   2
2   1
2   1
2   0
3   0
3   2
3   0

Now for each id, I want to count the number of occurences of 0 and 1 and the number of occurences for that ID (the value can be any integer), so the end result should look something like this:

id  n0  n1  total
1   2   2   5
2   1   2   4
3   2   0   3

I managed to get the first and last row with this statement:

SELECT id, COUNT(*) FROM mytable GROUP BY id;

But I’m sort of lost from here. Any pointers on how to achieve this without a huge statement?

Answer 1

With MySQL, you can use SUM(condition):

SELECT   id, SUM(value=0) AS n0, SUM(value=1) AS n1, COUNT(*) AS total
FROM     mytable
GROUP BY id

See it on sqlfiddle.