Query two db using group by and display detail information

Question

I have two tables
1: itemInfo

product_id  brand   name    category 
1   Garden  Goodcake    cake

2: itemRecord

record_id sh         


        

Answer 1

JOIN them:

SELECT r.product_id, i.brand, i.name, i.category, DATE_FORMAT( r.inputTime, '%e-%b' ) AS inputTime, r.shopType, r.price AS minimum_price, r.record_id
FROM (  SELECT *
        FROM itemRecord
        WHERE product_id = '1'
        ORDER BY price ASC, inputTime DESC) AS r
INNER JOIN itemInfo As i
ON r.product_id = i.product_id
WHERE i.id = r.product_id
GROUP BY DATE(r.inputTime)
LIMIT 0, 7

Explanation:

I do an inner query which renders the table order by price ASC instead of the default, lets say id ASC. When you GROUP BY the rows, it uses the columns from the first row by default, which in this case is the one with lowest price.

Your solution didn't work since it might aswell have chosen the first id and not the lowest price row. The only column which was correct was the MIN( r.price ), but as you noticed that function did not affect the other columns in the result.