MySQL子查询问题

Question

To make this example simple, lets pretend my table has the following attributes.

Table

ID: Int
Amount: Int
nameId: Int

Records Ex

ID: 1
Amount: 2
nameId: 3

ID: 2
Amount: 2
nameId: 3

ID: 3
Amount: 1
nameId: 3

Currently I have the following query.

SELECT DISTINCT(amount) FROM server.`inventory` where nameid = 558

It gives me

Amount 1
Amount 2

Straight forward, it selects a unique records base on amount. However, how can I also include in my query so that it counts how many id's are using that amount with nameid 558

So the output should be

Amount 1, Used 1
Amount 2, Used 2

Answer 1

This is an aggregation query. You want group by and count() :

SELECT amount, COUNT(*)
FROM server.inventory 
WHERE nameid = 558
GROUP BY amount;