I have two entity class Category and Events.I need to join both the tables and fetch all records which matching the given condition
我的SQL查询
SELECT * FROM category c inner join `events` e on e.category_i=c.category_id where c.parent_category_id=1;
我怎么能把这个SQL查询转换为hql并获取数据？我试过下面但没有得到结果？对休眠来说非常新
Events entity class for hibernate mapping
import java.io.Serializable;
import java.util.Date;
import javax.persistence.*;
/**
* The persistent class for the user database table.
*
*/
@Entity
@Table(name = "events")
public class Events implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "event_id")
private int eventId;
@Column(name = "event_name")
private String eventName;
@Column(name = "event_description")
private String eventDescription;
@Column(name = "category_i")
private Integer categoryI;
public Integer getCategoryI() {
return categoryI;
}
public void setCategoryI(Integer categoryI) {
this.categoryI = categoryI;
}
@Column(name = "is_trending_event")
private Integer isTrendingEvent;
@Column(name = "image_url")
private String imageUrl;
private Integer status;
@Column(name = "created_date")
@Temporal(javax.persistence.TemporalType.DATE)
private Date createdDate;
@Column(name = "last_updated_date")
@Temporal(javax.persistence.TemporalType.DATE)
private Date lastUpdatedDate;
public Date getCreatedDate() {
return createdDate;
}
public void setCreatedDate(Date createdDate) {
this.createdDate = createdDate;
}
public Date getLastUpdatedDate() {
return lastUpdatedDate;
}
public void setLastUpdatedDate(Date lastUpdatedDate) {
this.lastUpdatedDate = lastUpdatedDate;
}
public int getEventId() {
return eventId;
}
public void setEventId(int eventId) {
this.eventId = eventId;
}
public String getEventName() {
return eventName;
}
public void setEventName(String eventName) {
this.eventName = eventName;
}
public String getEventDescription() {
return eventDescription;
}
public void setEventDescription(String eventDescription) {
this.eventDescription = eventDescription;
}
public Integer getIsTrendingEvent() {
return isTrendingEvent;
}
public void setIsTrendingEvent(Integer isTrendingEvent) {
this.isTrendingEvent = isTrendingEvent;
}
public String getimageUrl() {
return imageUrl;
}
public void setimageUrl(String imageUrl) {
this.imageUrl = imageUrl;
}
public Integer getStatus() {
return status;
}
public void setStatus(Integer status) {
this.status = status;
}
}
Category entity
import java.io.Serializable;
import java.util.Date;
import javax.persistence.*;
/**
* The persistent class for the user database table.
*
*/
@Entity
@Table(name = "category")
public class Category implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "category_id")
private int categoryId;
@Column(name = "category_name")
private String categoryName;
@Column(name = "parent_category_id")
private Integer parentCategoryId;
@Column(name = "created_date")
@Temporal(javax.persistence.TemporalType.DATE)
private Date createdDate;
@Column(name = "last_updated_date")
@Temporal(javax.persistence.TemporalType.DATE)
private Date lastUpdatedDate;
@ManyToOne
@JoinTable(name="events",joinColumns = @JoinColumn(name="category_i"))
private Events events;
public int getCategoryId() {
return categoryId;
}
public void setCategoryId(int categoryId) {
this.categoryId = categoryId;
}
public String getCategoryName() {
return categoryName;
}
public void setCategoryName(String categoryName) {
this.categoryName = categoryName;
}
public Integer getParentCategoryId() {
return parentCategoryId;
}
public void setParentCategoryId(Integer parentCategoryId) {
this.parentCategoryId = parentCategoryId;
}
public Date getCreatedDate() {
return createdDate;
}
public void setCreatedDate(Date createdDate) {
this.createdDate = createdDate;
}
public Date getLastUpdatedDate() {
return lastUpdatedDate;
}
public void setLastUpdatedDate(Date lastUpdatedDate) {
this.lastUpdatedDate = lastUpdatedDate;
}
}
Fetch category method
public ListsqlException,ClassNotFoundException,IOException {
Listcreatequery("select e from Category e inner join e.events where e.parentCategoryId=1");
//query.setParameter("id",id);
groupList = query.list();
} catch (Exception e) {
}
return groupList;
}
最佳答案
在使用ORM工具时,您需要考虑Java对象.
从您的问题我认为您尝试编写的查询将类似于：
public Listcreatequery("select c from Category c join fetch c.events where c.parentCategory.categoryId = 1");
//query.setParameter("id",id);
groupList = query.list();
return groupList;
}
为此,您需要更新类模型,如下所示：
import java.io.Serializable;
import java.util.Date;
import javax.persistence.*;
@Entity
@Table(name = "events")
public class Event implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "event_id")
private int eventId;
@Column(name = "event_name")
private String eventName;
@Column(name = "event_description")
private String eventDescription;
@ManyToOne
@JoinColumn(name = "category_i")
private Category category;
@Column(name = "is_trending_event")
private Integer isTrendingEvent;
@Column(name = "image_url")
private String imageUrl;
private Integer status;
@Column(name = "created_date")
@Temporal(javax.persistence.TemporalType.DATE)
private Date createdDate;
@Column(name = "last_updated_date")
@Temporal(javax.persistence.TemporalType.DATE)
private Date lastUpdatedDate;
...
}
和
import java.io.Serializable;
import java.util.Date;
import javax.persistence.*;
@Entity
@Table(name = "category")
public class Category implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "category_id")
private int categoryId;
@Column(name = "category_name")
private String categoryName;
@ManyToOne
@JoinColumn(name="parent_category_id")
private Category parentCategory;
@Column(name = "created_date")
@Temporal(javax.persistence.TemporalType.DATE)
private Date createdDate;
@Column(name = "last_updated_date")
@Temporal(javax.persistence.TemporalType.DATE)
private Date lastUpdatedDate;
@OnetoMany(mappedBy="category")
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