MySQL的加入任何回報，如果沒有數據

Question

public function getUserList() { 
     $sql = "SELECT users.id, users.name, about.profile_img, user_game_info.at_game, SUM(user_img.likes) AS likes FROM users 
       JOIN about ON users.id = about.uid 
       JOIN user_game_info ON about.uid = user_game_info.uid 
       INNER JOIN user_img ON user_game_info.uid = user_img.uid"; 
     $query = $this->db->query($sql, PDO::FETCH_ASSOC); 
     if ($query->rowCount()) { 
      $userList = $query->fetchAll(); 
      return $userList; 
     } 
     return false;  
    } 

它的工作原理，但如果我的user_img沒有UID，我想告訴喜歡數0 該查詢返回只有img_user有UID，如果沒有它沒沒有任何回報。

這僅適用於user_img。例如，查詢必須爲UID 3.返回0，因爲user_img沒有UID = 3，但它不返回任何數據UID 3.

Answer 1

OK我已經更新了SQL再試一次：

您需要左連接：

$sql = ' 
SELECT u.id, u.name, a.profile_img, ugi.at_game, SUM(ifnull(i.likes,0)) AS likes 
FROM users u 
LEFT JOIN about a ON u.id = a.uid 
LEFT JOIN user_game_info ugi ON u.id = ugi.uid 
LEFT JOIN user_img i ON u.id = i.uid 
GROUP BY 1';