1.hibernate中檢索主要有以下：
lazy=true|false|extra
fetch=select subselect join迫切的左外鏈結
batch-size 檢索的數量
cascade="all" 級聯操作
2.第一種lazy的使用：
2.1 classes.hbm.xml
hibernate:
select
student0_.id as id1_1_0_,
student0_.name as name2_1_0_,
student0_.class_id as class_id3_1_0_
from
student student0_
where
student0_.id=?
hibernate:
select
classes0_.id as id1_0_0_,
classes0_.name as name2_0_0_
from
classes classes0_
where
classes0_.id=?
hibernate:
select
stus0_.class_id as class_id3_0_1_,
stus0_.id as id1_1_1_,
stus0_.id as id1_1_0_,
stus0_.name as name2_1_0_,
stus0_.class_id as class_id3_1_0_
from
student stus0_
where
stus0_.class_id=?
student [id=1, name=tom, cls=classes [id=1, name=大資料0302]]
2.2 使用lazy="true"時，效果如下;
hibernate:
select
student0_.id as id1_1_0_,
student0_.name as name2_1_0_,
student0_.class_id as class_id3_1_0_
from
student student0_
where
student0_.id=?
hibernate:
select
classes0_.id as id1_0_0_,
classes0_.name as name2_0_0_
from
classes classes0_
where
classes0_.id=?
student [id=1, name=tom, cls=classes [id=1, name=大資料0302]]
2.3 使用lazy="extra"時，效果如下;
hibernate:
select
student0_.id as id1_1_0_,
student0_.name as name2_1_0_,
student0_.class_id as class_id3_1_0_
from
student student0_
where
student0_.id=?
hibernate:
select
classes0_.id as id1_0_0_,
classes0_.name as name2_0_0_
from
classes classes0_
where
classes0_.id=?
student [id=1, name=tom, cls=classes [id=1, name=大資料0302]]
3 第二種 fetch的使用
3.1 classes.hbm.xml
3.2fetch="join"時：
hibernate:
select
student0_.id as id1_1_0_,
student0_.name as name2_1_0_,
student0_.class_id as class_id3_1_0_
from
student student0_
where
student0_.id=?
hibernate:
select
classes0_.id as id1_0_1_,
classes0_.name as name2_0_1_,
stus1_.class_id as class_id3_0_3_,
stus1_.id as id1_1_3_,
stus1_.id as id1_1_0_,
stus1_.name as name2_1_0_,
stus1_.class_id as class_id3_1_0_
from
classes classes0_
left outer join
student stus1_
on classes0_.id=stus1_.class_id
where
classes0_.id=?
student [id=1, name=tom, cls=classes [id=1, name=大資料0302]]
3.2fetch="select"時：
ibernate:
select
student0_.id as id1_1_0_,
student0_.name as name2_1_0_,
student0_.class_id as class_id3_1_0_
from
student student0_
where
student0_.id=?
hibernate:
select
classes0_.id as id1_0_0_,
classes0_.name as name2_0_0_
from
classes classes0_
where
classes0_.id=?
student [id=1, name=tom, cls=classes [id=1, name=大資料0302]]
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