mysql - 一列的多个别名

Question

我知道我可以为列指定一个临时别名。例如:

select foo, length(foo) as bar from my_table

而且我知道我可以使用这些别名来获取它们的值:

select foo, length(foo) as bar from my_table order by bar asc

但有时我想让我的查询结果更具可读性，当别名中有空格时，我不能在查询的其余部分使用它的值:

select foo, length(foo) as "Foo's length" from my_table order by ? asc

有没有一种方法可以为查询定义一个别名，并在结果中看到一个别名？

Answer 1

为什么这行不通:

select foo, length(foo) as `Foo's length`
from my_table
order by `Foo's length` asc;

或者，使用带有列引用的旧式 order by:

select foo, length(foo) as `Foo's length`
from my_table
order by 2 asc;

或者，重复表达式:

select foo, length(foo) as `Foo's length`
from my_table
order by length(foo) asc;