HQL语句

HQL语句的语法

1.from子句

from Person

表明从Person持久化类中选出全部的实例。

推荐：from Person as p

2.select子句

select from Person as p

select .firstName from Person as p

select new list(, p.address) from Person as p

select new ClassTest(, p.address) from Person as p (有前提)

select as personName from Person as p

select new map( as personName) from Person as p (与new map()结合更普遍)

3.聚集函数

avg,count,max,min,sum

select count(*) from Person

select max(p.age) from Person as p

select || "" || p.address from Person as p

4.多态查询

from Person as p

from ng.Object o

from Named as n

5.where子句

from Person where name like "tom%"

from Person as p where like "tom%"

from Cat cat where like "kit%"

select * from cat_table as table1 cat_table as table2 where table1.mate =

table2.id and like "kit%"

from Foo foo where foo.bar.baz.customer.address.city like "fuzhou%"

from Cat cat, Cat rival where cat.mate = rival.mate

select cat, mate

from Cat cat, Cat mate

where cat.mate = mate

from Cat as cat where cat.id = 123

from Cat as cat where cat.mate.id = 69

from Person as person

where person.id.country = 'AU'

and person.id.medicareNumber = 123456

from Account as account

where account.owner.id.country = 'AU'

and account.owner.id.medicareNumber = 123456

from Cat cat where cat.class = DomesticCat

from Account as a where .firstName like "dd%" // 正确

from Account as a where like "dd%" // 错误

6.表达式

from DomesticCat cat where between 'A' and 'B'

from DomesticCat cat where in ('Foo', 'Bar', 'Baz')

from DomesticCat cat where not between 'A' and 'B'

from DomesticCat cat where not in ('Foo', 'Bar', 'Baz')

from DomesticCat cat where is null

from Person as p where p.address is not null

true 1, false 0

from Cat cat where cat.alive = true

from Cat cat where cat.kittens.size > 0

from Cat cat where size(cat.kittens) > 0

from Calendar cal where maxelement(cal.holidays) > current date

from Order order where maxindex(order.items) > 100

from Order order where minelement(order.items) > 10000

//操作集合元素

select mother from Cat as mother, Cat as kit

where kit in elements(foo.kittens)

//p的name属性等于集合中某个元素的name属性

select p from NameList list, Person p

where = some elements(s)

//操作集合元素

from Cat cat where exists elements(cat.kittens)

from Player p where 3 > all elements(p.scores)

from Show show where 'fizard' in indices(show.acts)

//items是有序集合属性，items[0]代表第一个元素

from Order order where order.items[0].id = 1234

//holidays是map集合属性，holidays[national day]是代表其中第一个元素

select person from Person person, Calendar calendar

where calendar.holidays['national day'] = person.birthDay

and person.nationality.calendar = calendar

//下面同时使用list集合和map集合属性

select item from Item item, Order order

where order.items[order.deliveredItemIndices[0]] = item and order.id = 11 select item from Item item, Order order

where order.items[maxindex(order.items)] = item and order.id = 11

select item from Item item, Order order

where order.items[size(order.items) - 1] = item