急 如何别名列

[hcwdedw]

如 select a from tax
我想把 表里的a 字段 在select 选出
变为
select form tax group by 新定义的字段名

[LoveSQL]

select a as 别名 from tax group by a

[zheninchangjiang]

select newcol from (select a as newcol from tax) a group by newcol

[zjcxc]

select 新字段名=a from tax group by a

[hcwdedw]

谢谢
给分 我先测测