Hibernate - Basic
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Here are a few ways to write more elaborate HQL queries: 1. Add WHERE clauses to filter results: String queryString = "from Student s where s.id = :id"; query.setParameter("id", 1111); 2. Join to related entities: String queryString = "select s from Student s join s.courses c"; 3. Use aggregation functions: String queryString = "select max(s.id) from Student s"; 4. Sort and paginate results: query.setFirstResult(10).setMaxResults(20); query.addOrder(Order.desc("name")); 5. Nest subqueries: String query
Hibernate - Basic
- 1. > Hiber t -Ba nae sic Present on 15th Feb 20 ed 12
- 2. @Before > OOPs Must > L w houtHiber t ife it nae 2
- 3. Definit ion > Obj R aiona M pping (OR )sol ion forJ V ect el t l a M ut AA > Itis apow ful high per ma obj /el t lper ence a quer ser ice er , for nce ectr aiona sist nd y v > M ps J V cl sses t daa se t bl a A A a o t ba a es > In E ish, pr ides t t getJ v obj s in a outofdaa se ngl ov ool o a a ect nd t ba 3
- 4. Obj M v R aiona M ect odel s el t l odel Relational Databases • Efficient data storage, retrieval and integrity of the data • Provide a “normalized” set of data 4
- 5. Obj - el t lmismach ectR aiona t > Ga ait r nul r y – Obj Or ed v Daa se T ect ient s. t ba ypes – UserDefined Col T (UDT ae notpora e - umn ypes ) r t bl Name UserID Password PAN City S tate Zip User Address LoginInfo Name City PAN Username State Password Zip 5
- 6. Obj - el t lmismach ectR aiona t > Inher a &Pol phism it nce ymor – Notsuppored in t r aiona model t he el t l – No pol phic quer ymor ies – Col ae stictyt umns r r l yped > Ident yM t it ismach – Obj Ident yv Obj E l y ect it s. ect quait – Differ obj s ca ma t t sa col orcol ent ect n p o he me umn umns – Daa se Ident yStaegies t ba it r t – Naur lKeys v sus Surogae Keys ta er r t 6
- 7. Obj - el t lmismach ectR aiona t > A t ssociaions – Obj R ences v sus F eign Keys ect efer er or – Dir ionait ofA t ect l y ssociaions – T bl a t ae aw ys one-o- nyorma t one a es ssociaions r l a t ma ny-o- – Obj a t ca be ma t ma ect ssociaions n ny-o- ny > Daat mismach t ype t 7
- 8. Obj - el t lma ectR aiona pping > T s/echniques t st e a r r e obj s fr adaa se ool t o or nd etiev ect om t ba > F om t code per iv itbeha es l av t lobj daa se r he spect e v ike irua ect t ba > Acompl e OR sol ion shoul pr ide: et M ut d ov – Ba CR funct l y sic UD ionait – A Obj - ient Quer F cil y n ectOr ed y a it – M ppingM a t suppor a et daa t – Ta ct lCa bil y r nsa iona pa it 8
- 9. W tHiber t offer ha nae s? > Decl r t e pr a aaiv ogr mming > Uses R ime R ect unt efl ion > Quer L ngua is SQLl y a ge -ike – Lev a pr a ’s knowedge er ges ogr mmer l > M ppings a – Defined a XM document ora a aions s L s s nnot t 9
- 10. Concept s > Configur t (cfg) aion > Session F ct y– cfg.buil a or dSessionF ct y() a or – is aca ofcompil ma che ed ppings forasingl daa se. e t ba – Is used t cr t Hiber t Sessions o eae nae > Session – sf.openSession() – Shor l ed t iv • T aybr bet een t a a t daast a empor r idge w he pp nd he t or ge – Pr ides CR oper t on Obj s ov UD aions ect – Wa aJ Connect /J EDaaSour r ps DBC ion 2E t ce – Ser es a afir l elobj ca v s st ev ect che 10
- 11. Concept s > Ta ct – session.beginTa ct r nsa ion r nsa ion() – itpr ides a r ct fr t underying impl aion (J JA ov bsta ion om he l ement t DBC, T ) – itis opt l iona 11
- 12. Lifecycl e > Ta r nsient – NotA t w h adaa se t bl ssociaed it t ba a e – Non-r nsa iona ta ct l > Per ed sist – Obj w h Daa se Ident y ect it t ba it – A t obj w aSession ssociaes ect ith – Ta ct l r nsa iona > Det ched a – no l ongerguaa eed t be in synch w h t daa se r nt o it he t ba 12
- 13. Achit ur r ect e Ima sour O’R IL Y ge ce E L 13
- 14. O/ M ppings R a > Hiber t M ppingdefine: nae a – Col t F d M ppings umn o iel a – Pr r Keyma &gener t Scheme imay pping aion – A t ssociaions – Colect l ions – Ca Setings ching t – Cust SQL om – A ma mor setings… nd ny e t 14
- 15. HBMma fil pping e > < hiber t ma nae- pping > pa ge= "com.t v nt in"> cka a a .doma > < cl ss na “St "> a me= udent > < id na "Id" col “ST NT t “l me= umn= UDE _ID" ype= ong"> > < gener t cl ss= "ident y" / aor a it > > </ id> > < pr t na “ST NT M “ / opery me= UDE _NA E > > < set na "cour t bl "ST NT me= ses" a e= UDE _COUR " ca de= "al SE sca l"> > < key col "ST NT / umn= UDE _ID" > > < ma t ma col "COUR _ID" ny-o- ny umn= SE > cl ss= “com.t v nt in.Cour / < / a a a .doma se" > set > < /a cl ss> > < / nae- pping> hiber t ma 15
- 16. A aion ba ma nnot t sed pping > @Entity > @Table( name = " students" ) > publ cl ss St { ic a udent @Id > @GeneratedValue > @Column( name = " student_id" ) > pr ae l st Id; iv t ong udent > @Column( name = " student_name" , nullable = false, length = 100) > pr ae St ingst Na iv t r udent me; > @ManyToMany( cascade = CascadeType.ALL) > @JoinTable( name = " student_course" , joinColumns = {@JoinColumn( name = " student_id" ) }, inverseJoinColumns = {@JoinColumn( name = " course_id" ) }) > pr ae Set Cour cour = newHa < Cour (0 iv t < se> ses shSet se> ); 16
- 17. Sa inga Obj v n ect > St st = newSt (); udent udent udent > POJ is cr t O eaed > ….. > St r aSession at > Session session = nul; l > Ta ct is st red r nsa ion at > Ta ct t = nul; r nsa ion x l > T obj is sa ed he ect v > ty{ r > T ta ct is commited he r nsa ion t > session = fa or ct y.openSession(); > t = session.beginTa ct x r nsa ion(); > T session is cl he osed > session.sa e(st ); v udent > t x.commit (); > } final { ly > session.cl ose(); > } 17
- 18. L dinga Obj oa n ect > St st = nul; udent udent l > St r aSession at > Session session = nul; l > POJ is l ded O oa > session = fa or ct y.openSession(); > PKa Obj Cl ss ae pr ided nd ect a r ov > ty{ r > T session is cl he osed > st = (St ) udent udent > session.get udent a id); (St .cl ss, > } final { ly > session.cl ose(); > } 18
- 19. Del inga Obj et n ect > Session session = nul; l > St r aSession at > Ta ct t = nul; r nsa ion x l > Ta ct is st red r nsa ion at > ty{ r > T obj is del ed he ect et > session = fa or ct y.openSession(); > T ta ct is commited he r nsa ion t > t = session.beginTa ct x r nsa ion(); > T session is cl he osed > session.del e(st ); et udent > t x.commit (); > … > } final { ly > session.cl ose(); > } 19
- 20. W kingw h Colect or it l ions > Ca r esentaparent-child/one-many r aionship usingmostoft a a a e n epr el t he v il bl J v Colect a a l ions > Per ence byr ch- bil y sist ea a it > No a sema ics t yourcolect dded nt o l ions > Aa a e Colect ma v il bl l ion ppings he t ba ppings ae defined byaforeign key t t ow paentent y > In t daa se ma r o he ning/ r it 20
- 21. Suppored A t t ssociaions > One-o- t one – M int ined w h For Keys in Daa se a a it eign t ba > One-o- ny/M ny-o- t ma a t one – Obj on t ‘one’ side ect he – Colect on t ma ‘side’ l ion he ny > M ny-o- a a t M ny – Use a‘mapping’ t bl in t daa se a e he t ba 21
- 22. A t At ibut ssociaions tr es > Inv se atibut used forbi- ect la t er tr e dir iona ssociaions > L zyL ding a oa – Configur perr aionship ed el t – Uses dyna pr a R ime mic oxies t unt > Ca dingSt es sca yl – “none” no oper t ae ca ded aions r sca – “al aloper t ae ca ded l” l aions r sca – E er oper t in Hiber t ha acorespondingca de st e v y aion nae s r sca yl 22
- 23. Hiber t Quer L ngua (HQL nae y a ge ) > A obj ified v sion ofSQL n ect er – Pol phic Quer ymor ies – Obj paa er in Quer ect r met s ies – Less v bose t n SQL er ha > Doesn’thide t pow ofSQL he er – SQLj Cat n pr s oins, resia oduct – Pr ect oj ions – A egaion (ma a g)a gr ggr t x, v nd ouping – Or ing der – Sub- ies quer 23
- 24. Hiber t Quer L ngua (HQL nae y a ge ) > Simpl HQLQuer est y – R ur alSt s et n l udent s e s s i o n = s e s s i o n F a c t o r y .openSession(); // query string – ‘Student’ refers to a Class not a Table String q u e r y S t r i n g = " f r o m S t u d e n t " ; // create, configure and execute the query List students = s e s s i o n .c r e a t e Q u e r y (q u e r y S t r i n g ).l i s t (); 24
- 25. Hiber t Quer L ngua (HQL nae y a ge ) > Amor el bor t HQLQuer e a ae y – R ur alst s w h st ids et n l udent it udent Student s t u d e n t = … s e s s i o n = s e s s i o n F a c t o r y .openSession(); // build a query string String q u e r y S t r i n g = “f r o m S t u d e n t a s s wh e r e s .s t u d e n t I d = :id ”; // create, configure and execute the query List students = s e s s i o n .createQuery(q u e r y S t r i n g ) .setObject(“id”, 12 2 2 2 ) .list(); 25
- 26. Hiber t Quer L ngua (HQL nae y a ge ) > Amor el bor t HQLQuer e a ae y – R ur alst s w h st ids et n l udent it udent Student s t u d e n t = … s e s s i o n = s e s s i o n F a c t o r y .openSession(); // build a query string String q u e r y S t r i n g = “f r o m S t u d e n t a s s wh e r e s .s t u d e n t I d in = :id l is t ”; // create, configure and execute the query List students = s e s s i o n .createQuery(q u e r y S t r i n g ) .setParameterList(“id l is t ”, <<l i s t o f i d >>) .list(); 26
- 27. Quer byCr er y it ia > Sa quer usingt Cr er A me y he it ia PI – R ur alst s w h st ids et n l udent it udent Student s t u d e n t = … s e s s i o n = s e s s i o n F a c t o r y .openSession(); // create and expression to match the given conference Expression e x p = Expression.eq(“studentId", 12 3 4 5 ); List addresses = session .createCriteria(S t u d e n t .class) .add(e x p ) .list(); 27
- 28. Quer byE mpl y xa e > R ur alst w h st id et n l udent it udent Student student = new Student(); student.setStudentId(12345); // create example object Example e x a m p l e = Example.create(s t u d e n t ) .ignoreCase() .enableLike(MatchMode.ANYWHERE); // create, configure and execute the query List matches = s e s s i o n .createCriteria(S t u d e n t .class) .add(e x a m p l e ).list(); 28
- 29. Inher a it nce > Suppor St aegies t rt – Singl t bl percl ss hier r eae a achy – J subcl sses oined a – Inher pr t fr super a it operies om cl sses 29
- 30. Singl t bl percl ss eae a > @E it nt y > @Inher a r t Inher a ype.SING E A E it nce(st aegy= it nceT L _T BL ) > @Discr t Col iminaor umn( > na "pl net me= a ype", > discr t T Discr t T iminaor ype= iminaor ype.STRING > ) > @Discr t V l iminaor aue("Pl ne") a > publ cl ss Pl ne { ... } ic a a > @E it nt y > @Discr t V l 3 ") iminaor aue("A 20 > publ cl ss A 20ext Pl ne { ... } ic a 3 ends a 30
- 31. J subcl sses oined a > @E it nt y > @Inher a r t Inher a ype.J D) it nce(st aegy= it nceT OINE > publ cl ss Boa impl s Ser l bl { ... } ic a t ement iaiza e > @E it nt y > publ cl ss F r ext Boa { ... } ic a ery ends t > @E it nt y > @Pr r oinCol imayKeyJ umn(na "BOA_ID") me= T > publ cl ss A ica a ext Boa { ... } ic a mer CupCl ss ends t 31
- 32. Inher fr super a it om cl sses > @M ppedSuper a a cl ss > publ cl ss Ba nt y{ ic a seE it > @Basic > @Tempor l empor l ype.T E A P) a(T aT IM ST M > publ Dae get a Updae(){ ... } ic t L st t > publ St ingget a Updaer { ... } ic r L st t () > ... > } > @E it cl ss Or ext Ba nt y{ nt y a der ends seE it > @Id publ Int get { ... } ic eger Id() > ... > } 32
- 33. Ca in Hiber t ching nae > 1stL el ev – Ta ct scoped ca pr ided byt Session. r nsa ion che ov he – Aw ys a a a e l a v il bl > 2nd L el ev – Pr scoped ca ocess che – Shaed byalSessions r l – Opt l iona – Pl bl impl aion, ca be cl er ugga e ement t n ust ed > Query – Use w h cae, pr e fir it r ofil st 33
- 34. Ca in Hiber t ching nae > @T bl me = "st s") a e(na udent @Ca bl chea e @Cache(usa = ge CacheConcurencyStaegy.R A R E r r t E D_W IT ) publ cl ss St { ic a udent 34
- 35. Lifecycl e 35
- 36. W t use? hy o > G sepaaion ofint aion t a t r oft a icaion ood r t egr t ier nd he est he ppl t > Independentofunderyingdaa se used l t ba > EfficientQuer forPer ma ies for nce – La Loa zy ding > L yer Design Pat n a ed ter > Aoid r ent t w v einv ing he heel > G communit suppor, l r pooloft l ood y t age aent 36
- 37. > T nk Y ha ou
Editor's Notes
- #3: 30 to 70% of developer time, maintenance
- #6: Granularity – Objects and tables are modeled at different level of granularity Table structure is often de-normalized for better performance Objects are more fined grained
- #8: Inheritance – Associations in java uni or bi, type of object impact association DB – no directionality, many to many relationship needs join table, id or FK impacts association Navigational differences
- #37: Lazy loading – OptionVolatility example