MySQL: Special Price Scenario

Databases
1

I am working on a hotel booking engine. There is a special price scenario where the customer will see a special price based on the dates the admin defines.

If the date the customer is booking a hotel room falls on the date range specified, the price they will see is what the admin has defined.

So if the admin defines prices for a date rage from 1st Jan to 31st Jan in the following way,

1st Jan 2011 to 15th Jan 2011 = $100 / per day
16th Jan 2011 to 16th Jan 2011 = $500 / per day
17th Jan 2011 to 31st Jan 2011 = $100 / per day


CREATE TABLE `special_prices` (
  `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  `date_start` DATE DEFAULT NULL,
  `date_end` DATE DEFAULT NULL,
  `special_price` DECIMAL(10,2) DEFAULT NULL,
  `status_id` TINYINT(4) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MYISAM AUTO_INCREMENT=4 DEFAULT CHARSET=latin1


INSERT INTO `mydb`.`special_prices`(`id`,`date_start`,`date_end`,`special_price`,`status_id`) VALUES ( NULL,'2011-01-1','2011-01-15','100','1');

INSERT INTO `mydb`.`special_prices`(`id`,`date_start`,`date_end`,`special_price`,`status_id`) VALUES ( NULL,'2011-01-16','2011-01-16','500','1');

INSERT INTO `mydb`.`special_prices`(`id`,`date_start`,`date_end`,`special_price`,`status_id`) VALUES (NULL,'2011-01-17','2011-01-31','100','1');

When I run the following query:


SELECT
  `id`,
  `date_start`,
  `date_end`,
  `special_price`
FROM `special_prices`
WHERE date_start >= '2011-01-12' AND date_end <= '2011-01-18'

The result I get:

id	date_start	date_end	special_price	
2	2011-01-16	2011-01-16	500.00

Ideally the query should fetch all the 3 rows since they meet my query. Does anyone of you know why is this happening?

Any help is appreciated.

2

Date_start of the first row is smaller than ‘2011-01-12’ and thus doesn’t meet the WHERE condition.
Date_end of the 3rd row is bigger than '‘2011-01-18’ and thus doesn’t meet the WHERE condition.

What you want is all rows where Date_start <= ‘2011-01-18’ AND Date_end >= ‘2011-01-12’ , that way you also get the rows that are only partially in the date range you specified in the WHERE clause.

3

Hi Guido,

Thanks for the reply. Now I get all the three records. However, it does not meet what I am actually looking for.

According the rates as mentioned above, can the query calculate the date difference and return the price accordingly?

This is the query what I am running to achieve my goal:


SELECT
  `id`,
  `date_start`,
  `date_end`,
  `special_price`,
  `status_id`,
  (DATEDIFF('2011-01-18','2011-01-12')+1)*special_price AS DD
FROM `special_prices`
WHERE date_start &lt;= '2011-01-18' AND date_end &gt;= '2011-01-12'

This is the result I get:


    id  date_start  date_end    special_price  status_id     DD  
------  ----------  ----------  -------------  ---------  -------
     1  2011-01-01  2011-01-15         100.00          1   700.00
     2  2011-01-16  2011-01-16         500.00          1  3500.00
     3  2011-01-17  2011-01-31         100.00          1   700.00

Where as the DD column should return the prices as

$400 ($100 * 4 days, 12th to 15th)
$500 ($500 *1 day, 16th to 16th)
$200 ($100 * 2 days, 17th to 18th)

Wondering if this can be done?

Many thanks