Coding Cheatsheets - Learn to Code

INNER JOIN (or just JOIN) The most frequently used clause is INNER JOIN. This produces a set of records which match in both the user and course tables, i.e. all users who are enrolled on a course: SELECT user.name, course.name FROM `user`INNER JOIN `course` on user.course = course.id; Result: user.name course.name Alice HTML5 Bob HTML5 Carline CSS3 David MySQL LEFT JOIN What if we require a list of all students and their courses even if they’re not enrolled on one? A LEFT JOIN produces a set of records which matches every entry in the left table (user) regardless of any matching entry in the right table (course): SELECT user.name, course.name FROM `user` LEFT JOIN `course` on user.course = course.id; Result: user.name course.name Alice HTML5 Bob HTML5 Emma (NULL) RIGHT JOIN Perhaps we require a list all courses and students even if no one has been enrolled? A RIGHT JOIN produces a set of records which matches every entry in the right table (course) regardless of any matching entry in ...

Join in codeigniter Join 3 tables by codeigniter $query = ee()->db->select('b.id,b.rec_date,b.status,b.member_id, b.merchant_name, b.order_number, b.shipping_company, b.tracking_number,b.optional_service, b.inspected, c.first_name, c.last_name, c.mailbox_number,d.group_title as membership') ->from('exp_incoming_order b') ->order_by('b.id','desc') ->join('exp_members c', 'b.member_id=c.member_id and '.$whereCond) ->join('exp_member_groups d', 'd.group_id=c.group_id') ->limit($this->perpage, $rownum) ->get();