Question 63816 in PhpMyAdmin Question posted in
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The Sum of people that have same age in SQL? – Phpmyadmin

I’m taking a SQL class and I need help with a question.

I have the following table on a phpmyadmin server

patient (id, age)

with a total of 100 patients

I’m told to find the sum of people that have same age using SQL.

I wrote this query:

SELECT COUNT(age) 
FROM patient 
HAVING (COUNT(age) > 1);

but it returns 100 as a result and when I did this query and found the number of patients who have the same age for each age and calculated the count manually I found 78 and I checked it manually and it’s indeed 78.

SELECT COUNT(*) 
FROM patient 
GROUP BY age 
HAVING (COUNT(*) > 1);

What’s wrong with my code?

Tags:

2

Answers


  1. 0

    Start with a subquery that gets the counts of people with each age. Then filter this to counts more than 1 so it’s just people with the same age.

    Then in the main query you use SUM() to add all these counts together, to get the total number of patients.

    SELECT SUM(count)
FROM (
    SELECT COUNT(*) AS count
    FROM patient
    GROUP BY age
    HAVING count > 1
) AS x
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  2. 0 
        select age, count(*) from patient group by age;
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