Java 使用布尔函数从中选择
我正在尝试用JavaEE开发一个应用程序。下面是我想要实现的类图的一部分: 下面是hibernate类的实现:Java 使用布尔函数从中选择,java,hibernate,many-to-many,jpql,Java,Hibernate,Many To Many,Jpql,我正在尝试用JavaEE开发一个应用程序。下面是我想要实现的类图的一部分: 下面是hibernate类的实现: @Entity @Table(name = "t_enseignant") public class Enseignant extends User implements Serializable { private static final long serialVersionUID = 1L; private String specialite; priva
@Entity
@Table(name = "t_enseignant")
public class Enseignant extends User implements Serializable {
private static final long serialVersionUID = 1L;
private String specialite;
private List<Module> modules;
public Enseignant() {
}
public Enseignant(String nom, String prenom, String email, String login, String password, String specialite) {
super(nom, prenom, email, login, password);
this.setSpecialite(specialite);
}
public String getSpecialite() {
return specialite;
}
public void setSpecialite(String specialite) {
this.specialite = specialite;
}
@OneToMany(mappedBy = "enseignant")
public List<Module> getModules() {
return modules;
}
public void setModules(List<Module> modules) {
this.modules = modules;
}
}
@Entity
@Table(name = "t_classe")
public class Classe implements Serializable {
private static final long serialVersionUID = 1L;
private int id;
private String niveau;
private int nbreEtudiant;
private List<Module> modules;
public Classe() {
}
public Classe(String niveau, int nbreEtudiant) {
this.niveau = niveau;
this.nbreEtudiant = nbreEtudiant;
}
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
public int getId() {
return id;
}
...
@延斯
@Entity
@Table(name = "t_module")
public class Module implements Serializable {
private static final long serialVersionUID = 1L;
private ModulePk modulePk;
private String nomModule;
private int nbreHeure;
private Enseignant enseignant;
private Classe classe;
public Module() {
}
public Module(String nomModule, int nbreHeure, Enseignant enseignant, Classe classe) {
this.nomModule = nomModule;
this.nbreHeure = nbreHeure;
this.enseignant = enseignant;
this.classe = classe;
this.modulePk = new ModulePk(enseignant.getId(), classe.getId());
}
@EmbeddedId
public ModulePk getModulePk() {
return modulePk;
}
public void setModulePk(ModulePk modulePk) {
this.modulePk = modulePk;
}
public String getNomModule() {
return nomModule;
}
public void setNomModule(String nomModule) {
this.nomModule = nomModule;
}
public int getNbreHeure() {
return nbreHeure;
}
public void setNbreHeure(int nbreHeure) {
this.nbreHeure = nbreHeure;
}
@ManyToOne
@JoinColumn(name = "idEnseignant", referencedColumnName = "id", insertable = false, updatable = false)
public Enseignant getEnseignant() {
return enseignant;
}
public void setEnseignant(Enseignant enseignant) {
this.enseignant = enseignant;
}
@ManyToOne
@JoinColumn(name = "idClasse", referencedColumnName = "id", insertable = false, updatable = false)
public Classe getClasse() {
return classe;
}
public void setClasse(Classe classe) {
this.classe = classe;
}
}
这是ModulePK类
@Embeddable
public class ModulePk implements Serializable {
private static final long serialVersionUID = 1L;
private int idEnseignant;
private int idClasse;
public ModulePk() {
}
public ModulePk(int idEnseignant, int idClasse) {
this.setIdEnseignant(idEnseignant);
this.setIdClasse(idClasse);
}
...
@延斯
@Entity
@Table(name = "t_module")
public class Module implements Serializable {
private static final long serialVersionUID = 1L;
private ModulePk modulePk;
private String nomModule;
private int nbreHeure;
private Enseignant enseignant;
private Classe classe;
public Module() {
}
public Module(String nomModule, int nbreHeure, Enseignant enseignant, Classe classe) {
this.nomModule = nomModule;
this.nbreHeure = nbreHeure;
this.enseignant = enseignant;
this.classe = classe;
this.modulePk = new ModulePk(enseignant.getId(), classe.getId());
}
@EmbeddedId
public ModulePk getModulePk() {
return modulePk;
}
public void setModulePk(ModulePk modulePk) {
this.modulePk = modulePk;
}
public String getNomModule() {
return nomModule;
}
public void setNomModule(String nomModule) {
this.nomModule = nomModule;
}
public int getNbreHeure() {
return nbreHeure;
}
public void setNbreHeure(int nbreHeure) {
this.nbreHeure = nbreHeure;
}
@ManyToOne
@JoinColumn(name = "idEnseignant", referencedColumnName = "id", insertable = false, updatable = false)
public Enseignant getEnseignant() {
return enseignant;
}
public void setEnseignant(Enseignant enseignant) {
this.enseignant = enseignant;
}
@ManyToOne
@JoinColumn(name = "idClasse", referencedColumnName = "id", insertable = false, updatable = false)
public Classe getClasse() {
return classe;
}
public void setClasse(Classe classe) {
this.classe = classe;
}
}
这是ModulePK类
@Embeddable
public class ModulePk implements Serializable {
private static final long serialVersionUID = 1L;
private int idEnseignant;
private int idClasse;
public ModulePk() {
}
public ModulePk(int idEnseignant, int idClasse) {
this.setIdEnseignant(idEnseignant);
this.setIdClasse(idClasse);
}
...
您忘记了使用
:
来指示命名参数,因此您使用了idEnseignant=idEnseignant
而不是idEnseignant=:idEnseignant
以下是更正后的代码:
boolean exists = false;
String jpql = "select case when (count(m) > 0) then true else false end from Module m where m.idEnseignant=:idEnseignant and m.idClasse=:idClasse";
TypedQuery<Boolean> query = entityManager.createQuery(jpql, Boolean.class);
query.setParameter("idEnseignant", enseignant.getId());
query.setParameter("idClasse", classeToValidate.getId());
exists = query.getSingleResult();
return exists
boolean exists=false;
String jpql=“选择case when(count(m)>0),然后选择true或false结束模块m,其中m.idEnseignant=:idEnseignant和m.idClasse=:idClasse”;
TypedQuery query=entityManager.createQuery(jpql,Boolean.class);
setParameter(“idEnseignant”,enseignant.getId());
setParameter(“idClasse”,classeToValidate.getId());
exists=query.getSingleResult();
回报存在
您忘记了使用:
来指示命名参数,因此您使用了idEnseignant=idEnseignant
而不是idEnseignant=:idEnseignant
以下是更正后的代码:
boolean exists = false;
String jpql = "select case when (count(m) > 0) then true else false end from Module m where m.idEnseignant=:idEnseignant and m.idClasse=:idClasse";
TypedQuery<Boolean> query = entityManager.createQuery(jpql, Boolean.class);
query.setParameter("idEnseignant", enseignant.getId());
query.setParameter("idClasse", classeToValidate.getId());
exists = query.getSingleResult();
return exists
boolean exists=false;
String jpql=“选择case when(count(m)>0),然后选择true或false结束模块m,其中m.idEnseignant=:idEnseignant和m.idClasse=:idClasse”;
TypedQuery query=entityManager.createQuery(jpql,Boolean.class);
setParameter(“idEnseignant”,enseignant.getId());
setParameter(“idClasse”,classeToValidate.getId());
exists=query.getSingleResult();
回报存在
在模块
实体中,您将模块pk
定义为主键。有两种可能使用此id:
- 创建
类的实例,并将其传递给实体管理器的ModulePk
方法(在查询中不是这样),或者find()
- 要在JPQL查询中使用它,必须遍历嵌入的id类。在您的情况下,请按如下方式使用:
String jpql = "select case when (count(m) > 0) then true else false end from Module m where m.modulePk.idEnseignant = :idEnseignant and m.modulePk.idClasse = :idClasse";
模块
实体中,您将模块pk
定义为主键。有两种可能使用此id:
- 创建
类的实例,并将其传递给实体管理器的ModulePk
方法(在查询中不是这样),或者find()
- 要在JPQL查询中使用它,必须遍历嵌入的id类。在您的情况下,请按如下方式使用:
String jpql = "select case when (count(m) > 0) then true else false end from Module m where m.modulePk.idEnseignant = :idEnseignant and m.modulePk.idClasse = :idClasse";