I am having the following 2 tables in my database:
product_price
CREATE TABLE `product_price` (
`asin` varchar(10) NOT NULL,
`date` date NOT NULL,
`price` decimal(7,2) NOT NULL DEFAULT '0.00',
PRIMARY KEY (`asin`,`date`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
product_info
CREATE TABLE `product_info` (
`asin` varchar(10) NOT NULL,
`name` varchar(200) DEFAULT NULL,
`brand` varchar(50) DEFAULT NULL,
`part_number` varchar(50) DEFAULT NULL,
`url` text,
`image` text,
PRIMARY KEY (`asin`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
I want to find the products which its price has been reduced between a start date and a end date.
I am using the following query right now which works:
$query = "SELECT pi.*, prev.price AS 'old_price', curr.price, ROUND((100.0*(curr.price - prev.price) / prev.price),0) As PercentDiff FROM product_price As curr
JOIN product_price As prev ON curr.date = '".$end_date."' AND prev.date = '".$start_date."'
JOIN product_info pi ON curr.asin = pi.asin WHERE curr.asin = prev.asin HAVING PercentDiff < 0 ORDER BY PercentDiff";
But the problem is that table product_price has not has a record if the price has not changed.
Eg for example
asin date price
AAAAAAAAA 2018-07-17 7
AAAAAAAAA 2018-07-15 6
start_date= "2018-07-16" end_date="2018-07-17"
I want it to have it in my results as price was reduced.
How i had to change my query??
I tried to change prev.date = '".$start_date."' to prev.date <= '".$start_date."'
But returns all the records and not the closest one as i want.
Here is some sample data from product_price:
+------------+------------+--------+
| asin | date | price |
+------------+------------+--------+
| B000GBKDB4 | 2018-07-02 | 38.66 |
| B000GBKDCI | 2018-07-02 | 72.98 |
| B000GBKFLW | 2018-07-02 | 33.27 |
| B000GBKFMG | 2018-07-02 | 63.45 |
| B000GBLZEI | 2018-07-02 | 34.90 |
| B000GBLZEI | 2018-07-04 | 21.31 |
| B000GBLZEI | 2018-07-05 | 20.24 |
| B000GBLZEI | 2018-07-06 | 18.41 |
| B000GBLZEI | 2018-07-08 | 17.49 |
| B000GBLZEI | 2018-07-09 | 15.79 |
| B000GBLZEI | 2018-07-11 | 14.84 |
| B000GBLZEI | 2018-07-16 | 14.29 |
Still not very clear what you are after but this should select the correct prices applicable for a pair of dates. 2018-07-03 to 2018-07-07 that don't appear in the product_price table.
Hopefully this will set you on the right track.
SELECT *,
(SELECT price
FROM product_price
WHERE product_price.asin = product_info.asin AND
product_price.date <= '2018-07-03'
ORDER BY product_price.date DESC
LIMIT 1) AS start_price,
(SELECT price
FROM product_price
WHERE product_price.asin = product_info.asin AND
product_price.date <= '2018-07-07'
ORDER BY product_price.date DESC
LIMIT 1) AS end_price
FROM product_info
WHERE asin = 'B000GBLZEI'
Following on from your comment, you could use a temporary table like this
CREATE TEMPORARY TABLE IF NOT EXISTS price_changes (
asin VARCHAR(10),
start_price DECIMAL(7,2),
end_price DECIMAL(7,2));
TRUNCATE price_changes;
INSERT INTO price_changes
SELECT asin,
(SELECT price
FROM product_price
WHERE product_price.asin = product_info.asin AND
product_price.date <= '2018-07-03'
ORDER BY product_price.date DESC
LIMIT 1) AS start_price,
(SELECT price
FROM product_price
WHERE product_price.asin = product_info.asin AND
product_price.date <= '2018-07-07'
ORDER BY product_price.date DESC
LIMIT 1) AS end_price
FROM product_info;
SELECT *,
ROUND((100.0 * (end_price - start_price) / start_price), 0) AS price_difference
FROM product_info
JOIN price_changes ON
price_changes.asin = product_info.asin;
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