mysql - 从单个表中检索数据以与mysql中的另一个表进行比较

Question

SELECT *
FROM `room_type`
WHERE h_id='$h_id'
  AND `rt_oc` >= '$tperson'
  AND `rt_num` <
    (SELECT COUNT(`check_out`)
     FROM `room_info`
     WHERE `h_id`='$h_id'
       AND
       LEFT JOIN `room_type` ON room_type.rt_type=room_info.room_type));

这里我想从表 1 中选择数据，它将比较表 2 中相同列值的总和的列值。

Answer 1

WHERE `h_id`='$h_id'
       AND
       LEFT JOIN

这行不通，需要像这样更新子查询:

(SELECT COUNT(`check_out`)
     FROM `room_info`
     LEFT JOIN `room_type` ON room_type.rt_type=room_info.room_type
     WHERE `h_id`='$h_id')

顺便说一句，你有 )); 在查询的末尾 - 检查它。

SELECT *
FROM `room_type`
WHERE h_id='$h_id'
  AND `rt_oc` >= '$tperson'
  AND `rt_num` <
    (SELECT COUNT(`check_out`)
     FROM `room_info`
     LEFT JOIN `room_type` ON room_type.rt_type=room_info.room_type
     WHERE `h_id`='$h_id')