概述
- HQL（Hibernate Query Language）提供更加丰富灵活、强大的查询功能
- HQL 语句形式：select .... from .... where .... group by .... having .... order by ....
- 最简单的 HQL 只需要一个 FROM 就可以够成
- HQL 对大小写敏感，关键字不区分大小写
- HQL 是面向对象的查询语言
HQL 语句参考：
from Card
from Card where cardName = 'DOTA'
from Card where cardName like '%林%'
from Card c where c.createDate > '2011-08-08'
from Card c where c.createDate between '2011-08-08' and '2022-11-11'
from Card c where c.createDate between '2011-08-08' and '2022-11-11' and c.cardname like '%林%'
update Card as c set c.createDate = '2011-03-03' where c.cardType.cardTypeId = 3
delete from Card c where c.createDate = '2011-03-04'
select c.cardName from Card c where c.cardType.cardTypeId = 1
- 多个属性查询，其中cardTypeName直接通过card对象的cardType获取，省去SQL必须的多表连接
select c.cardName,c.cardType.cardTypeName,c.createDate from Card as c where c.cardType.cardTypeId=1
select new Card(c.cardName,c.createDate) from Card as c
select count(*),max(c.createDate) from Card as c
from Card as c order by c.createDate desc
from Card as c group by c.cardType.cardTypeId
select c.cardType from Card as c
select c.cardType from Card as c where c.cardType.cardTypeId=:id
from Card as c inner join c.cardType
from CardType as c left join c.cards
from CardType as c right join c.cards
from CardType as c where (select count(*) from c.cards>0)
