MySQL：如何将当前 select 语句中创建的两个字段的结果相加？

Question

我正在创建一个 MySQL 视图表，所以到目前为止我的代码看起来像这样：

CREATE VIEW `myview`
AS SELECT
    (do some stuff here) AS `Revenue1`,
    (do some more here)  AS `Revenue2`
FROM ...

现在我想添加一个列是这两个字段的总和，所以我尝试了这个：

CREATE VIEW `myview`
AS SELECT
    (do some stuff here) AS `Revenue1`,
    (do some more here)  AS `Revenue2`,
    (`Revenue1` + `Revenue2`) AS `TotalRevenue`
FROM ...

但这会导致错误提示 Revenue1 字段未知。如何添加这两个字段并将结果作为新列获取？

Answer 1

你必须重复以下内容：

CREATE VIEW `myview`
AS SELECT
    (do some stuff here) AS `Revenue1`,
    (do some more here)  AS `Revenue2`,
    ((do some stuff here) + (do some more here)) AS `TotalRevenue`
FROM ...

或创建第二个视图：

CREATE VIEW `myview_Two`
AS SELECT
    `Revenue1`,
    `Revenue2`,
    `Revenue1` + `Revenue2` AS `TotalRevenue`
FROM myview

Answer 2

我认为这应该可行：

CREATE VIEW `myview` 
AS 
  SELECT 
       (do some stuff here) AS `Revenue1`,     
       (do some more here)  AS `Revenue2`,     
       (do some stuff here) + (do some more here) AS `TotalRevenue`
  FROM ...