Select rows where all criteria matches from a key value table

Question

I have the following query:

select *
    from user_interests
    join interests using(interest_id)
    where tag in('running', 'biking')
    and user_id != 1;

Note: The in() values are built dynamically using php, so their could be one value or 100 values, each passed in via user browser $_GET .

My user_interests table is pretty simple, as it is just a list of the interest_id and the user_id .

CREATE TABLE `user_interests` (
  `interest_id` INT(10) UNSIGNED NOT NULL,
  `user_id` INT(10) UNSIGNED NOT NULL,
  PRIMARY KEY (`interest_id`, `user_id`)
);

My interests table is a simple table that holds a list of different types of interests ( running , biking , etc.)

CREATE TABLE `interests` (
  `interest_id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  `tag` VARCHAR(50) NOT NULL,
  `category_id` TINYINT(3) UNSIGNED NOT NULL,
  PRIMARY KEY (`interest_id`),
  UNIQUE INDEX `tag` (`tag`)
);

Since each user can have many interests, how can I search the database for users that have all of the interests in the list. For the query above that would be running and biking . My query just gets people who have at least one of the above, how can I make it so it gets users who have all of the queried interests?

So if a user has 5 interests, and I pass in 2 and they have those 2 in their list of 5, their profile should be returned. If they only have 1 of the 2 passed in there profile should not be returned.

Here is a Fiddle: http://sqlfiddle.com/#!9/29ea2

Answer 1

I would try that

SELECT *
FROM user_interests
WHERE user_interests.user_id IN (
            SELECT ui.user_id
            FROM user_interests ui
            left join interests i using(interest_id)
            WHERE i.tag IN ($php_array)
                                ^ PHP
            and ui.user_id != 1
            GROUP BY ui.user_id
            HAVING COUNT(i.tag) >= count($php_array)
                                  ^ PHP
)

Fiddle