# 14.5\. select子句 `select` 子句选择将哪些对象与属性返 回到查询结果集中. 考虑如下情况: ``` select mate from Cat as cat inner join cat.mate as mate ``` 该语句将选择`mate`s of other `Cat`s。（其他猫的配偶） 实际上, 你可以更简洁的用以下的查询语句表达相同的含义: ``` select cat.mate from Cat cat ``` 查询语句可以返回值为任何类型的属性，包括返回类型为某种组件(Component)的属性: ``` select cat.name from DomesticCat cat where cat.name like 'fri%' ``` ``` select cust.name.firstName from Customer as cust ``` 查询语句可以返回多个对象和（或）属性，存放在 `Object[]`队列中, ``` select mother, offspr, mate.name from DomesticCat as mother inner join mother.mate as mate left outer join mother.kittens as offspr ``` 或存放在一个`List`对象中, ``` select new list(mother, offspr, mate.name) from DomesticCat as mother inner join mother.mate as mate left outer join mother.kittens as offspr ``` 也可能直接返回一个实际的类型安全的Java对象, ``` select new Family(mother, mate, offspr) from DomesticCat as mother join mother.mate as mate left join mother.kittens as offspr ``` 假设类`Family`有一个合适的构造函数. 你可以使用关键字`as`给“被选择了的表达式”指派别名: ``` select max(bodyWeight) as max, min(bodyWeight) as min, count(*) as n from Cat cat ``` 这种做法在与子句`select new map`一起使用时最有用: ``` select new map( max(bodyWeight) as max, min(bodyWeight) as min, count(*) as n ) from Cat cat ``` 该查询返回了一个`Map`的对象，内容是别名与被选择的值组成的名-值映射。