Question

I have a MySQL DB with three tables: categories (can be subcategories), items and item_categories (because item can belong to several categories).

SQL code:

CREATE TABLE `categories` (
`id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
`parent_id` INT NOT NULL ,
`name` TEXT NOT NULL
)

CREATE TABLE `items` (
`id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
`cat_id` INT,
`title` TEXT NOT NULL ,
`price` VARCHAR( 10 ) NOT NULL
)

CREATE TABLE `item_categories` (
`id` INT NOT NULL AUTO_INCREMENT ,
`item_id` INT NOT NULL ,
`cat_id` INT NOT NULL ,
PRIMARY KEY (`id`)
)

So the question is: for a list of categories how to get count of offers?

Answer 1

SELECT COUNT(*) cnt, cat_id
FROM item_categories
WHERE cat_id IN (1, 2, 3)
GROUP BY cat_id

Where (1, 2, 3) is a list of categories you’re interested about