Question

I don’t think this is possible but I wanted to make sure.

Lets say I wanted to get the average age of users assuming some conditions.

SELECT avg(age) as avg_a FROM users where something something;

Now the say the client wants to get average age, average age for male and average age for female.

so something like

SELECT avg(age) as avg_a, avg(age where female) avg_f, avg(age where male) avg_m FROM users where something something;

Is something like this even possible or even wise?

How would I go about doing it? Or should I just run 3 queries every time?

Answer 1

Yes, you can use a case statement within your aggregation function. See:

SELECT
    avg(age) avg_age,
    avg(case when gender = 'M' then age end) male_avg_age,
    avg(case when gender = 'F' then age end) female_avg_age
FROM users;