Question

In my database table I have two columns that hold either 0 or 1.

I have type and Gender, where type means 0 => teacher and 1 => student and for gender: 0 => male and 1 => female.

How can I write a single sql query to get number of teachers, students, males and females?

Right now I have:

select COUNT(type) as teachers from my_table where type = 0; // Teachers
select COUNT(type) as students from my_table where type = 1; // Students
select COUNT(gender) as males from my_table where type = 0; // Males
select COUNT(gender) as females from my_table where type = 1; // Females

Can it be done in one query? If so, how?

Answer 1

This way you can do it in a single query. If you have only two types of data in your table then you don’t need to specify IN conditions in WHERE clause:

SELECT SUM(IF(type = 1, 1, 0)) as students,
       SUM(IF(type = 0, 1, 0)) as teachers,
       SUM(IF(gender = 1, 1, 0)) as females,
       SUM(IF(gender = 0, 1, 0)) as males
FROM my_table
WHERE type IN(0,1)
      AND gender IN(0,1);