Aggregate Functions

Aggregate functions can be used with the GROUP BY clause.

Minimum / Maximum

The MIN keyword is used to find the minimum value in a field, and MAX is used to find the maximum. These work for both numeric and text values.

Find the dob of the oldest and youngest pet.

SELECT MIN(dob), MAX(dob)
    FROM Pet;

Average

SELECT AVG(cost)
    FROM Vaccine;

Sum

SELECT SUM(cost)
    FROM Vaccination, Vaccine
    WHERE vaccination.vaxID = vaccine.vaxID
        AND pet_id = 14;

Count

Count the number of records in a table that meet the condition.

SELECT COUNT(*)
    FROM Pet
    WHERE species = "Rabbit";