mysql - 引用 mySQL 查询组件

Question

有没有办法在同一查询中引用 MySQL 查询的各个部分？

例如:

SELECT 50000 AS starting_principle, .065*50000 AS interest, 
    principle + interest AS principle_plus_interest

查询集中的第三列 principle_plus_interest 给我一个错误。除了编写 50000 + .065*50000 AS principle_plus_interest 之外，还有其他编码方法吗？

Answer 1

您不能在 select 列表(或 where 子句)中引用别名。解决此问题的一种方法是使用子查询:

SELECT starting_principle, 
       interest, 
       principle + interest AS principle_plus_interest 
FROM   (SELECT 50000 AS starting_principle, .065*50000 AS interest
        FROM   some_table) t