MySQL中or语句用法示例

$sql = 'SELECT 
        * 
      FROM 
        `vvt_spread_doubleegg_exchange_award` AS p
      WHERE
        p.`act_type` = 4 or p.`act_type` = 5
      AND
        p.`user_id` = ' .$user_id
      ;

 $sql = 'SELECT * FROM `vvt_spread_doubleegg_exchange_award` AS p WHERE p.`act_type` = 4;
 $sql = 'SELECT * FROM `vvt_spread_doubleegg_exchange_award` AS p WHERE p.`act_type` = 5 AND p.`user_id` = ' .$user_id;

$sql = 'SELECT 
        * 
      FROM 
        `vvt_spread_doubleegg_exchange_award` AS p
      WHERE
        （p.`act_type` = 4 or p.`act_type` = 5）
      AND
        p.`user_id` = ' .$user_id
      ;