在MySQL SELECT语句中,派生字段如何利用SELECT列表中另一个字段的值？

Question

例如,运行以下查询时:

SELECT
 'tim' AS first_name
,first_name || ' example' AS full_name;

我希望结果如下:

first_name, full_name
tim       , tim example

相反,我收到以下错误:

Unknown column 'first_name' in 'field list'.

有没有办法可以引用另一列？

谢谢
Turgs

Answer 1

不,您必须重复它或使用派生表.

select *, concat(first_name,  ' example') as full_name
 from (
select
 'tim' as first_name ) as t