MYSQL, dynamic rows to columns [duplicate]

Answer 1

This is often called a pivot. There's no way to do a pivot without hard-coding one column per distinct value. This means you need to know the set of distinct values before you write the SQL query.

SELECT u.user_id, u.user_name,
  COALESCE(MAX(IF(u_p.prod=1, 1, 0), 0) AS `u_p_prod=1`,
  COALESCE(MAX(IF(u_p.prod=2, 1, 0), 0) AS `u_p_prod=2`,
  COALESCE(MAX(IF(u_p.prod=3, 1, 0), 0) AS `u_p_prod=3`,
  COALESCE(MAX(IF(u_p.prod=4, 1, 0), 0) AS `u_p_prod=4`
FROM user AS u
LEFT OUTER JOIN u_p ON u.user_id = u_p.u_p_user
GROUP BY u.user_id;