Question

考虑以下代码：

SELECT SUM(w.valor),
SUM(CASE WHEN w.tipo = '+' THEN w.valor ELSE 0 END) AS total_credit,
SUM(CASE WHEN w.tipo = '-' THEN w.valor ELSE 0 END) AS total_debit,
w.clientUNIQUE,
c.client as cclient
FROM wallet AS w
LEFT JOIN clients AS c ON w.clientUNIQUE = c.clientUNIQUE
WHERE w.status='V'
GROUP BY w.clientUNIQUE
ORDER BY total_credit-total_debit

我尝试计算两个别名计算值的差异以进行排序，但我收到以下错误：

参考＆＃39; total_credit＆＃39;不支持（参考群组功能）

我做错了什么以及如何使用两个别名之间的差值来订购结果？

Answer 1

您无法在同一个选择表达式中按别名引用列，因此有2个选项...

重复order by（yuk）中的表达式：

ORDER BY
  SUM(CASE WHEN w.tipo = '+' THEN w.valor ELSE 0 END) AS total_credit -
  SUM(CASE WHEN w.tipo = '-' THEN w.valor ELSE 0 END) AS total_debit

大脑更容易维护（DRY），通过子查询订购：

select * from (
  <your query without the ORDER BY>
) q
ORDER BY total_credit - total_debit

如何计算排序的两个别名的差异

1 个答案: