20. Hibernate Hibernate Query Language

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Nguyn Hong Anh nhanh@fit.hcmus.edu.vn H KHTN - 2012
Ni dung trnh by
Hibernate Query Language (HQL)
HQL from
HQL select
HQL aggregate function
HQL where
HQL - Expression
HQL order by
HQL group by & having
HQL sub query 2

JDBC - SQL
JDBC s dng cc cu lnh SQL thc hin truy vn d liu truy vn d liu v cc thao tc cp nht nh thm, xa, sa trn bng d liu.
thao tc tt cc cu lnh SQL cn quan tm n cc bng, cc dng, cc ct v mi quan h gia cc bng v c bit l h qun tr c s d liu ang lm vic.
Kt qu tr v ca cu lnh truy vn l danh sch cc dng d liu.
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Hibernate - HQL
Hibernate cung cp cc API cho php thc hin tc thao tc cp nht nh thm, xa, sa.
Hibernate cung cp ngn ng truy vn rt mnh c gi l Hibernate Query Language (HQL).
HQL c lp h qun tr c s d liu v c Hibernate thng dch sang SQL tng ng trong qu trnh thc thi.
HQL l ngn ng truy vn theo hng i tng. Kt qu truy vn l i tng
Hibernate s dng cc lp i tng v cc thuc tnh thay cho cc bng v cc ct.
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HQL Phn bit hoa thng
HQL khng phn bit thng hoa ngoi tr
Tn cc lp i tng
Cc thuc tnh trong lp i tng
V d 2 cu truy vn ging nhau
select s from Sach s SELECT s FROM Sach s
Select s From Sach s SELECT s FROM Sach s
V d 2 cu truy vn khc nhau
select s from sach s SELECT s FROM Sach s
Select s From SACH s SELECT s FROM Sach s
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HQL Mnh from
Ly tt c c i tng danh mc
from DanhMuc
select dm from DanhMuc dm
select dm from DanhMuc as dm
Ly tt c i tng sch
from Sach
select s from Sach s
select s from Sach as s
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HQL Mnh from ly tt c i tng
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String hql = "from Sach"; Query query = session.createQuery(hql); List ds=query.list();

HQL Mnh from - phn trang
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String hql = "from Sach"; Query query = session.createQuery(hql); query.setFirstResult(3); query.setMaxResults(5); List ds=query.list();
- Ly t v tr th n (tnh t 0) setFirstResult (int n) - ly ti a m i tng setMaxResults (int m) - Tng t trong MYSQL LIMIT N, M

HQL - join
cross join
inner join hoc join
left join hoc left outer join
right join hoc right outer join
left join fetch hoc left outer join fetch
right join fetch hoc right outer join fetch
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HQL cross join
Thc hin tch cartesian (cn gi l cross join)
from Sach, DanhMuc
from Sach s, DanhMuc dm
select s,dm from Sach s, DanhMuc dm
Kt qu tr v l mt ArrayList
S lng phn t = s lng danh mc * s lng sch
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HQL cross join
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String hql = "from Sach s, DanhMuc dm"; Query query = session.createQuery(hql); ArrayList ds = query.list(); for(int i=0; i

HQL inner join
S lng danh mc: 4
S lng sch: 10 (u thuc danh mc)
inner join
from DanhMuc dm
inner join dm.sachs
Kt qu
S lng: 10
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HQL left join
S lng danh mc: 4 (2 danh mc khng c sch)
Left join
from DanhMuc dm
left join dm.sachs
Kt qu
S lng: 12
2 danh mc khng c
sch no thuc v
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HQL right join
S lng danh mc: 4
Right join
from DanhMuc dm
right join dm.sachs
Kt qu
S lng: 10
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HQL left join fetch
S lng danh mc: 4 (c
Left join fetch
from Sach s left join fetch
s.danhMuc
Kt qu
S lng: 10
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HQL right join fetch
S lng danh mc: 4 (c
right join fetch
from Sach s right join fetch
s.danhMuc
Kt qu
S lng: 10
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HQL - select
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String hql = "select s.danhMuc from Sach s"; Query query = session.createQuery(hql); List ds=query.list();

HQL - select
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String hql = "select s.danhMuc.tenDanhMuc from Sach s";
Query query = session.createQuery(hql);
List ds=query.list();

HQL - select
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String h ="select s.maSach, s.tenSach, s.danhMuc from Sach s"; Query query = session.createQuery(h); List ds=query.list(); for(int i=0; i

HQL - select
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String hql ="select distinct s.danhMuc.tenDanhMuc from Sach s"; Query query = session.createQuery(hql); List ds=query.list();

HQL - select
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package pojo; public class MyClass { private String maSach; private String tenSach; private DanhMuc danhMuc; public MyClass() { } public MyClass(String maSach, String tenSach, DanhMuc danhMuc) { this.maSach = maSach; this.tenSach = tenSach; this.danhMuc = danhMuc; } //Getters & Setters }

HQL - select
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String hql = "select new pojo.MyClass (s.maSach, s.tenSach, s.danhMuc) from Sach s"; Query query = session.createQuery(hql); List ds=query.list(); for(int i=0; i

HQL - Aggregate functions
avg
min
max
count
sum
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HQL - Aggregate functions
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String hql = " select avg(s.giaBan) as GiaTrungBinh," + " count(*) as SoLuongDauSach," + " min(s.giaBan) as GiaBanThapNhat," + " max(s.giaBan) as GiaBanCaoNhat, " + " sum(s.soLuong) as TongSoLuongSach " + " from Sach s"; Query query = session.createQuery(hql); Object[] objs = (Object[]) query.uniqueResult(); double giaTrungBinh=(Double)objs[0]; long soLuongDauSach=(Long)objs[1]; double giaBanThapNhat=(Double)objs[2]; double giaBanCaoNhat=(Double)objs[3]; long tongSoLuongSach=(Long)objs[4];

HQL - where
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String tenSach="Java"; String hql = "from Sach s where s.tenSach like :tenSach"; Query query = session.createQuery(hql); query.setString("tenSach", "%"+tenSach+"%"); ArrayList ds=query.list();
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String tenDanhMuc="Java"; String giaBan=20000; String hql="from Sach s where s.danhMuc.tenDanhMuc=:tenDanhMuc and s.giaBan>:giaBan" Query query = session.createQuery(hql); query.setString("tenDanhMuc", tenDanhMuc); query.setString("giaBan", giaBan); ArrayList ds=query.list();

HQL - Expression
+, -, *, /
=, >=,

HQL - Expression
concat(...,...)
current_date(), current_time(), current_timestamp()
second(...), minute(...), hour(...), day(...), month(...), year(...)
substring(), trim(), lower(), upper(), length(), locate(), abs(), sqrt(), bit_length(), mod()
coalesce() , nullif()
str(), ...
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HQL order by
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String tenSach="Java"; Str

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