最大和计数查询

Question

I'm trying to make a query with max and count like this one: (taken from http://www.w3resource.com/sql/aggregate-functions/max-count.php )

SELECT MAX (mycount)   
FROM (SELECT agent_code,COUNT(agent_code) mycount   
FROM orders   
GROUP BY agent_code);  

this query returns a column with the name 'MAX(MYCOUNT)' with the max value: '7',the simple change I want is that I would like to get the agent code of the one who got the maximum, instead of the max records of agent code.

tried to do this in some ways but no luck so far, hope you can help me to do this right.

Answer 1

If you don't have to worry about a tie for two agents having the max number of orders, then you can try the following:

SELECT agent_code, COUNT(*) AS mycount
FROM orders
GROUP BY agent_code
ORDER BY COUNT(*) DESC
LIMIT 1

If you do have to worry about a tie for the max number of orders, and you want all ties, then you can use a subquery:

SELECT agent_code, COUNT(*) AS mycount
FROM orders
GROUP BY agent_code
HAVING COUNT(*) = (SELECT MAX(t.mycount) FROM
                   (SELECT COUNT(*) AS mycount FROM orders GROUP BY agent_code) t)

Answer 2

You can use order by and limit :

SELECT agent_code, COUNT(agent_code) as mycount   
FROM orders   
GROUP BY agent_code
ORDER BY mycount DESC
LIMIT 1;