【发布时间】：2015-10-09 04:00:05
【问题描述】：
我有两个实体类 Category 和 Events。我需要加入两个表并获取与给定条件匹配的所有记录
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;
如何将此 sql 查询转换为 hql 并获取数据？我在下面尝试但没有得到结果？我对休眠很陌生
用于休眠映射的事件实体类
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;
}
}
类别实体
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;
}
}
获取类别方法
public List<Object[]> getCategoryList(int id) throws SQLException, ClassNotFoundException, IOException {
List<Object[]> groupList = null;
try {
Session session = sessionFactory.getCurrentSession();
Query query = session.createQuery("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;
}
【问题讨论】：
-
您可以使用休眠条件，并且有一个用于获取连接的属性。
-
@Darshan，请帮我做这件事。 :(
-
您的映射错误，您认为 JDBC 不是休眠，您映射的是对象而不是 id。在您的
Event中，您应该有一个Category对象而不是一个 id。 -
如果您不介意，请提供答案，以便我清楚地了解映射方式。
标签： java mysql spring hibernate