有条件和的内连接

Question

So I have 3 tables, where I need to get the sum of the price column grouped by the day_of_week column, and only return the sum for the day_of_week , that has the lowest sum.

In other words, all the venues have a number of services, and through those services, they have available_days and a price. So the price for a given day for the venue, is the sum of it's services price for a given day. I need the sum for a given day, that is the lowest, eg the lowest price of the week.

This is my query so far:

SELECT * , SUM( ad.price ) AS venue_price
FROM venues AS v
JOIN services AS s ON v.id = s.serviceable_id
JOIN available_days AS ad ON s.id = ad.available_id
WHERE ad.available_type =  'Service'
AND s.type =  'basic'
AND ad.available =1
GROUP BY ad.day_of_week
HAVING venue_price < 500000
ORDER BY venue_price
LIMIT 1

Here is a fiddle: http://sqlfiddle.com/#!2/37ee20/1/0

This works when I have one venue, but the problem is that it should get ALL the venues, that have a venue_price under 500000. How do i get it to only select the available_days entry with the lowest price, without limiting it to only one venue?

Answer 1

If you need record with lowest sum, lets sort it by price and set LIMIT to 1 :

SELECT * , SUM( ad.price ) AS price
FROM venues AS v
JOIN services AS s ON v.id = s.serviceable_id
JOIN available_days AS ad ON s.id = ad.available_id
WHERE ad.available_type =  'Service'
AND s.type =  'basic'
AND ad.available = 1
ORDER BY price ASC
LIMIT 1