add a column in MySQL rank by deal by day - mysql

Question

I am just learning MySQL. I need to find out rank of deals by day. Here I am adding the corresponding MYSQL query for my requirement that currently ranks all sales highest to lowest by day. Please help me to add a column that gives the rank to the deal highest to lowest and resetting the next day.
Here is my current working query,..
single day with title, price
SELECT
DATE(order_items.created_at) AS the_day,
order_items.deal_id,
SUM(order_items.item_total) AS daily_total,
SUM(order_items.qty) AS units_sold,
deals.price,
deals.title
FROM
order_items JOIN deals ON order_items.deal_id = deals.id
WHERE
order_items.created_at >= '2016-01-01 00:00:00' AND order_items.created_at < '2016-01-30 00:00:00'
AND
order_items.status=1
AND
order_items.paid=1
GROUP BY
order_items.deal_id
ORDER BY
the_day,
daily_total DESC;

Answer 1

The easiest way to do is that:
Use your existing SQL - I guess you need to update your SQL, make sure any non-aggregated columns in select should be in group by as well
Use PHP to loop (1-5), it works for multiple days
If you are happy to get top 5 for a single day, you can add limit 5 at end of your SQL
If you need top 5 results for each day in multiple days in one SQL, you need to update SQL to be more complicated. And here is a hint to use row id see example:
select increment counter in mysql
OK - Since you updated your question to return top 1 result per day, this is easier:
Step 1: get each day, each deal, report:
SELECT deal_id, date(created_at) ymd, sum(item_total) daily_total, sum(qty) units_sold
FROM order_items
WHERE substr(created_at,1,7) = '2016-01'
AND status = 1
AND paid = 1
GROUP BY 1,2
Step 2: Find the best deal of each day from step 1:
SELECT aa.ymd, max(aa.daily_total) max_total
FROM (
SELECT deal_id, date(created_at) ymd, sum(item_total) daily_total, sum(qty) units_sold
FROM order_items
WHERE substr(created_at,1,7) = '2016-01'
AND status = 1
AND paid = 1
GROUP BY 1,2
) as aa
GROUP BY 1;
Please note that max(item_total) not necessary same row as max(unit_sold), so you need to choose one, and cannot run togather
Step 3: Join step 2 with step 1 and deals to find out the rest of information:
SELECT aa.*, deals.price, deal.title
FROM (
SELECT aa.ymd, max(aa.daily_total) max_total
FROM (
SELECT deal_id, date(created_at) ymd, sum(item_total) daily_total, sum(qty) units_sold
FROM order_items
WHERE substr(created_at,1,7) = '2016-01'
AND status = 1
AND paid = 1
GROUP BY 1,2
) as aa
GROUP BY 1
) as bb
JOIN (
SELECT deal_id, date(created_at) ymd, sum(item_total) daily_total, sum(qty) units_sold
FROM order_items
WHERE substr(created_at,1,7) = '2016-01'
AND status = 1
AND paid = 1
GROUP BY 1,2
) as aa ON bb.ymd = aa.ymd and bb.max_total = aa.daily_total
JOIN deals ON aa.deal_id = deals.id
ORDER BY aa.ymd, aa.max_total