Question

我有一个mysql查询，它从多行中减去金额，以在名为“Balance”的新列中显示新金额。我希望它只显示那些平衡＆gt;的记录。 '0'。见下文：

    SELECT 
visits.visit_id,
visits.payment_increments,
((visits.total - visits.paid) - SUM(payments.amount)) AS Balance,
schedule.schedule_date
FROM
visits
    LEFT OUTER JOIN
schedule ON visits.schedule_id = schedule.id
    LEFT OUTER JOIN
payments ON visits.visit_id = payments.visit_id
WHERE
Balance>'0'
GROUP BY visits.visit_id

有没有办法在WHERE语句中使用我的新列？现在，它显示的只是一个错误 - ＆gt;错误代码：1054'where子句'中的未知列'Balance'。

非常感谢任何帮助！

Answer 1

使用HAVING代替WHERE

GROUP BY ... HAVING Balance >0

注意： HAVING适用于非表格列。由于余额不是主表的列，所以这是一个虚构的列，因此它可以与HAVING一起使用，就像WHERE适用于表格列

一样

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Answer 2

  SELECT 
visits.visit_id,
visits.payment_increments,
((visits.total - visits.paid) - SUM(payments.amount)) AS Balance,
schedule.schedule_date
FROM
visits
    LEFT OUTER JOIN
schedule ON visits.schedule_id = schedule.id
    LEFT OUTER JOIN
payments ON visits.visit_id = payments.visit_id

GROUP BY visits.visit_id HAVING  Balance>'0'

Answer 3

您可以使用相同的SQL查询，只需提及完整列名称

即可

   SELECT 
   visits.visit_id,
   visits.payment_increments,
   ((visits.total - visits.paid) - SUM(payments.amount)) AS Balance,
   schedule.schedule_date
  FROM
     visits
    LEFT OUTER JOIN
   schedule ON visits.schedule_id = schedule.id
   LEFT OUTER JOIN
  payments ON visits.visit_id = payments.visit_id
WHERE
  ((visits.total - visits.paid) - SUM(payments.amount))>'0'
 GROUP BY visits.visit_id

在我的mysql where语句中使用“as column”

3 个答案: