I have three tables:
table "package" ----------------------------------------------------- package_id int(10) primary key, auto-increment package_name varchar(255) price decimal(10,2) table "zones" ------------------------------------------------------ zone_id varchar(32) primary key (ex of data: A1, Z2, E3, etc) table "package_zones" ------------------------------------------------------ package_id int(10) zone_id varchar(32)
What I'm trying to do is return all the information in package table PLUS a list of zones for that package. I want the list of zones sorted alphabetically and comma separated.
So the output I'm looking for is something like this...
+------------+---------------+--------+----------------+ | package_id | package_name | price | zone_list | +------------+---------------+--------+----------------+ | 1 | Red Package | 50.00 | Z1,Z2,Z3 | | 2 | Blue Package | 75.00 | A2,D4,Z1,Z2 | | 3 | Green Package | 100.00 | B4,D1,D2,X1,Z1 | +------------+---------------+--------+----------------+
I know I could do something in PHP with the presentation layer to get the desired result. The problem is, I would like to be able to sort zone_list ASC or DESC or even use" WHERE zone_list LIKE" and so on. In order to do that, I need this done in MYSQL.
I have NO idea how to even begin to tackle this. I tried using a subquery, but it kept complaining about multiple rows. I tried to concat the multiple rows into a single string, but evidently MySQL doesn't like this.
Thanks in advance.
UPDATE!
Here is the solution for those who are interested.
SELECT `package`.*, GROUP_CONCAT(`zones`.`zone` ORDER BY `zones`.`zone` ASC SEPARATOR ',' ) as `zone_list` FROM `package`, `package_zones` LEFT JOIN (`zones`,`ao_package_zones`) ON (`zones`.`zone_id` = `package_zones`.`zone_id` AND `package_zones`.`package_id` = `package`.`package_id`) GROUP BY `ao_package`.`package_id`
The GROUP_CONCAT() function in MySQL is used to concatenate data from multiple rows into one field. This is an aggregate (GROUP BY) function which returns a String value, if the group contains at least one non-NULL value.
You may use the IN, ANY, or ALL operator in outer query to handle a subquery that returns multiple rows. Contents: Using IN operator with a Multiple Row Subquery. Using NOT IN operator with a Multiple Row Subquery.
A single-row subquery is used when the outer query's results are based on a single, unknown value. Although this query type is formally called "single-row," the name implies that the query returns multiple columns-but only one row of results.
by using the GROUP_CONCAT() function and a GROUP BY call. here's an example query
SELECT p.package_id, p.package_name, p.price, GROUP_CONCAT(pz.zone_id SEPARATOR ',') as zone_list FROM package p LEFT JOIN package_zone pz ON p.package_id = pz.package_id GROUP BY p.package_id
you should still be able to order by zone_id s (or zone_list), and instead of using LIKE
, you can use WHERE zp.zone_id = 'Z1'
or something similar.
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