计算重复记录

Question

Suppose I have a table named studens.

I want to count how many students who received duplicated scores at least 2 times. Please help me, thanks.

The result that I expect is: Jonh have 100 score 2 times, James have 80 scores 2 times, Julia has 50 scores 2 times. So the amount of students who receive duplicated score at least 2 times is 3 (Jonh, Jam, and Julia).

Answer 1

select count(*) from
(
    select name
    from your_table
    group by name, score
    having count(*) > 1
) x