将多个SQL语句合并为一个

Question

如何在单个SQL语句中组合这些语句？

select city from station where city like 'a%';

select city from station where city like 'e%';

select city from station where city like 'i%';

select city from station where city like 'o%';

select city from station where city like 'u%'; 

Answer 1

显而易见的方法是union all:

select city from station where city like 'a%' union all
select city from station where city like 'e%' union all
. . . 

也许几乎同样明显的是:

where city like 'a%' or city like 'e%' or . . . 

您还可以使用其他方法,例如:

where left(city, 1) in ('a', 'e', 'i', 'o', 'u')

(注意:并非所有数据库都支持left().)

更典型的方法是某种形式的正则表达式,但该语法取决于数据库.