PostgreSQL-别名列和HAVING

本文介绍了PostgreSQL-别名列和HAVING的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

SELECT
CASE WHEN SUM(X.Count)*3600 is null THEN  '0'
            ELSE
            SUM(X.Count)*3600
       END AS PJZ,
       X.Mass
FROM X
WHERE X.Mass > 2000
HAVING ((X.Mass / PJZ * 100) - 100) >= 10;

获取：错误：»pjz«列不存在。

Getting: ERROR: Column »pjz« doesn't exists.

我该怎么做？

推荐答案

将其包装到派生表中：

SELECT CASE
          WHEN PJZ = 0 THEN 100
          ELSE PJZ
       END as PJZ,
       mass
FROM (
    SELECT CASE
             WHEN SUM(X.Count)*3600 is null THEN '0'
             ELSE SUM(X.Count)*3600
           END AS PJZ,
           X.Mass
    FROM X
    WHERE X.Mass > 2000
    GROUP BY X.mass
) t
WHERE PJZ = 0
   OR ((X.Mass / PJZ * 100) - 100) >= 10;

（请注意，我添加了缺少的组，否则查询将无效）

(Note that I added the missing group by as otherwise the query would not be valid)

这篇关于PostgreSQL-别名列和HAVING的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！