mysql group by to return a the min value and get the corresponding row data

Question

I have a table of data like so :

- PK_table - merchantName - price - Product
- 1        - argos        - 7     - 4
- 2        - comet        - 3     - 4
- 1        - Dixon        - 1     - 3
- 1        - argos        - 10    - 4

I wish to select the minimum price for a product and the corresponding merchant in mysql.

I tried:

SELECT Product, merchantName, min(price)
FROM a_table
GROUP BY product

however the result returned is incorrect since it chooses the first merchant name and not the corresponding merchant of the MIN.

how do you do it?

Answer 1

SELECT Merchant.Product, Merchant.Name, Merchant.Price
FROM a_table AS Merchant
JOIN
(
SELECT Product, MIN(Price) AS MinPrice
FROM a_table
GROUP BY Product
) AS Price
ON Merchant.Product = Price.Product
AND Merchant.Price = Price.MinPrice

Will return two rows if two merchants have the same low, low price.