Question

I’m using CodeIgniter’s db class to create the query.

The query ends up looking like this;

    SELECT `user_id`, `firstname`, `lastname`, `email`, `school_id`, `country_id`
    FROM (`users`)
    WHERE `user_id` != '1'
    AND `firstname` =  'thomas'
    OR `lastname` =  'thomas'
    OR `email` =  'thomas'
    OR `firstname` =  'jefferson'
    OR `lastname` =  'jefferson'
    OR `email` =  'jefferson'

In this case a user has searched for “thomas jefferson” and the user’s own id is 1. So to make sure the user can’t search for himself it checks so that the user_id isn’t 1.

I know the query isn’t that good but it works perfectly for what I need it for, as well as me being too lazy to do it correctly.

The PHP-code behind this all is

    $this->db->select('user_id, firstname, lastname, email, school_id, country_id')->from('users');
    $this->db->where('user_id !=', $this->session->userdata('user_id'));
    for ($i = 0; $i < count($searchQuery); $i++) {
        if ($i == 0) {
            $this->db->where('firstname', $searchQuery[$i])->or_where('lastname', $searchQuery[$i])->or_where('email', $searchQuery[$i]);
        } else {
            $this->db->or_where('firstname', $searchQuery[$i])->or_where('lastname', $searchQuery[$i])->or_where('email', $searchQuery[$i]);
        }
    }
    $this->db->limit(10);
    $query = $this->db->get();

I’m 99% positive that the

    WHERE `user_id` != '1'
    AND(<-- this) `firstname` = ...

is wrong but I can’t seem to figure out a different way to do it.

Answer 1

Take a look at Operation Precedence in sql server.
In there you will find that AND operations are evaluated before OR operations.

That means your query is first evaluating the AND :

user_id != '1' AND firstname = 'thomas'

and then

OR blablablablabla (the rest of the query)

To make it correct it would be simply like this:

   SELECT `user_id`, `firstname`, `lastname`, `email`, `school_id`, `country_id`
    FROM (`users`)
    WHERE `user_id` != '1'
    AND (`firstname` =  'thomas'
    OR `lastname` =  'thomas'
    OR `email` =  'thomas'
    OR `firstname` =  'jefferson'
    OR `lastname` =  'jefferson'
    OR `email` =  'jefferson')