Question

我绝对是hibernate的新手，这实际上让我烦恼。即使查询正确，它也可以找到该表。这个问题可以解决什么问题？

这是我的dao中错误仍然存在的部分------------------------------------ --------------------------------

@Override
    public void emptyCart() {

        Session session = HibernateUtil.getSessionFactory().openSession();
        Transaction transaction = session.beginTransaction();

        String sqlQuery = "DELETE from ShoppingCart";
        Query query = session.createQuery(sqlQuery);

        query.executeUpdate();

        transaction.commit();
        session.close();
    }

下面是stacktrace ------------------------------------------- -------------------------------------------------- ----------

 SEVERE: Servlet.service() for servlet [appServlet] in context with path [/NutsAboutCandyWebProject] threw exception [Request processing failed; nested exception is org.hibernate.exception.SQLGrammarException: could not execute statement] with root cause
    com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'db_nutsaboutcandy.shopping_cart_shopping_cart' doesn't exist
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
        at com.mysql.jdbc.Util.getInstance(Util.java:386)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1054)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4237)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4169)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2617)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2778)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2825)
        at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2156)
        at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2441)
        at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2366)
        at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2350)
        at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:187)
        at org.hibernate.hql.internal.ast.exec.BasicExecutor.doExecute(BasicExecutor.java:109)
        at org.hibernate.hql.internal.ast.exec.DeleteExecutor.execute(DeleteExecutor.java:121)
        at org.hibernate.hql.internal.ast.QueryTranslatorImpl.executeUpdate(QueryTranslatorImpl.java:445)
        at org.hibernate.engine.query.spi.HQLQueryPlan.performExecuteUpdate(HQLQueryPlan.java:374)
        at org.hibernate.internal.SessionImpl.executeUpdate(SessionImpl.java:1286)
        at org.hibernate.internal.QueryImpl.executeUpdate(QueryImpl.java:118)
        at com.nutsaboutcandywebproject.dao.SQLShoppingCartDataAccess.emptyCart(SQLShoppingCartDataAccess.java:61)
        at com.nutsaboutcandywebproject.service.ServiceFacadeImpl.emptyCart(ServiceFacadeImpl.java:221)
        at com.nutsaboutcandywebproject.controller.OrderController.orderSuccessful(OrderController.java:209)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:690)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:945)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:928)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:539)
        at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:300)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:724)

ShoppingCart实体

package com.nutsaboutcandywebproject.model;

import java.io.Serializable;
import java.util.List;

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

@Entity
@Table(name = "shopping_cart", catalog = "db_nutsaboutcandy")
public class ShoppingCart implements Serializable {

    private static final long serialVersionUID = 1L;

    private Integer cartId;
    private Integer userId;
    private Integer productId;
    private Integer sizeId;
    private Integer numberOfItems;


    private List<ShoppingCart> cart;

    @ElementCollection
    public List<ShoppingCart> getCart() {
        return cart;
    }

    public void setCart(List<ShoppingCart> cart) {
        this.cart = cart;
    }

    public ShoppingCart(){
        super();
    }

    public ShoppingCart(Integer cartId, Integer userId, Integer productId,
            Integer sizeId, Integer numberOfItems) {
        super();
        this.cartId = cartId;
        this.userId = userId;
        this.productId = productId;
        this.sizeId = sizeId;
        this.numberOfItems = numberOfItems;
    }

    @Id
    @GeneratedValue
    @Column(name="cart_id", nullable = false)
    public Integer getCartId() {
        return cartId;
    }

    public void setCartId(Integer cardId) {
        this.cartId = cardId;
    }

    @Column(name="user_id", nullable = false)
    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }



    @Column(name="product_id", nullable = false)
    public Integer getProductId() {
        return productId;
    }

    public void setProductId(Integer productId) {
        this.productId = productId;
    }


    @Column(name="size_id", nullable = false)
    public Integer getSizeId() {
        return sizeId;
    }

    public void setSizeId(Integer sizeId) {
        this.sizeId = sizeId;
    }

    @Column(name = "number_of_items", nullable = false)
    public Integer getNumberOfItems() {
        return numberOfItems;
    }

    public void setNumberOfItems(Integer numberOfItems) {
        this.numberOfItems = numberOfItems;
    }

}

Answer 1

你有什么是HQL查询，而不是SQL查询。所以ShoppingCart是实体名称，而不是表名。 HQL从不使用表名和列名。它总是使用实体名称及其字段名称。

您告诉Hibernate每个购物车都包含购物车列表。这不是现实。

要获取所有购物车的列表，请执行HQL查询：

select c from ShoppingCart c

并且Hibernate将查询数据库并返回购物车列表。

Answer 2

即使我遇到同样的问题。我在配置文件中设置了“hibernate.hbm2ddl.auto = update”。

hibernate.hbm2ddl.auto创建SessionFactory时，自动验证或将架构DDL导出到数据库。使用create-drop，当SessionFactory显式关闭时，将删除数据库模式。

e.g。验证|更新|创建|创建降

所以可能的选项列表是，

验证：验证架构，不对数据库进行任何更改。更新：更新架构。 create：创建架构，销毁以前的数据。 create-drop：在会话结束时删除模式。

使用hibernate表不存在

2 个答案: