org.hibernate.exception.GenericJDBCException：无法插入：

Question

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).
log4j:WARN Please initialize the log4j system properly.
Hibernate: insert into purchase_details (date, total_quantity, total_weight, type) values (?, ?, ?, ?)
HE:org.hibernate.exception.GenericJDBCException: could not insert: [com.focus.beans.PurchaseDetailsList]

已创建表，但值未插入表中...我该如何解决此问题？

package com.focus.beans;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

import lombok.Getter;
import lombok.Setter;



@Entity
@Table(name = "purchase_details")
public class PurchaseDetailsList {
    @Id @GeneratedValue
    @Column (name="type_id")
    @Getter @Setter private String type_id;
    
    @Column (name = "type")
    @Getter @Setter private String type; 

    @Column(name = "date")
    @Getter @Setter private String date;
    
    @Column (name = "total_quantity")
    @Getter @Setter private String totalquantity;
    
    @Column (name = "total_weight")
    @Getter @Setter private String totalweight;
}

这是我的bean类......表被创建并被重定向到下一页，但是我们输入的值没有插入到数据库中。

MyController.class

package com.focus.controller;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.focus.beans.PurchaseDetailsList;
import com.focus.dao.Dao;

public class PurchaseDetail extends HttpServlet {
    private static final long serialVersionUID = 1L;

    PrintWriter out = null;
    boolean flag;
    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        Dao dao = Dao.getInstance();
        
        PurchaseDetailsList pdl = new PurchaseDetailsList();
        
        pdl.setType(request.getParameter("types"));
        pdl.setDate(request.getParameter("date"));
        pdl.setTotalquantity(request.getParameter("totalquantity"));
        pdl.setTotalweight(request.getParameter("totalweight"));
        //System.out.println("Am arun");
        
        flag =  dao.persist(pdl);
            response.getWriter();
            response.sendRedirect("JSP/PurchaseDetailsListForm.jsp");
    }
}

但是给定的值没有插入到表中，并且抛出异常：

org.hibernate.exception.GenericJDBCException: could not insert:

我该如何修复它？

Answer 1

如果你查看生成的休眠查询

Hibernate: insert into purchase_details (date, total_quantity, total_weight, type) values (?, ?, ?, ?)

primary key

未正确填充，您已使用

@GeneratedValue

来映射您的

primary key

，而没有任何

strategy

。 因此默认情况下

Hibernate

使用策略

AUTO

。

来自 Hibernate 文档

AUTO - either identity column, sequence or table depending on the underlying DB

因此

hibernate

根据您使用的数据库选择策略。

可以尝试使用

sequence generator

@Id
@GeneratedValue(strategy=GenerationType.AUTO, generator="purchase_seq")
@SequenceGenerator(name="purchase_seq", sequenceName="PURCHASE_SEQ")
private String type_id;

其中

PURCHASE_SEQ

是您应创建数据库的序列的名称。