JPA数据操作汇总，常用的数据操作方法都在这了

前言

写博客总结，最近公司进新人，写了个内部文档顺便整理了一下jap的数据操作demo

正文

第一种方式：

根据客户名称查询客户，使用jpql的形式查询，配置jpql语句，使用的@Query注解

@Query(value="from Customer where custName = ?1")
    public Customer findJpql(String custName);      

第二种方式：

使用sql的形式查询，

Query：配置sql查询

value：sql语句
nativeQuery：查询方式
  true：sql查询
  false：jpql查询      

@Query(value="select * from cst_customer where cust_name like ?1",nativeQuery = true)
    public List<Object [] > findSql(String name);      

第三种方式：

方法名的约定：

findBy: 查询
  对象种的属性名称（首字母大写）： 查询条件
  例如：数据库中的字段 cust_name  方法名：findByCustName
  默认情况： 默认使用的是等于的方式查询      

列举两种种特殊情况：

1.findBy  + 属性名称 + “查询方式（Like | isnull）”
方法名：findByCustNameLike
2.多条件查询
  findBy + 属性名 + “查询方式”   + “多条件的连接符（and|or）”  + 属性名 + “查询方式”      

第四种方式：

使用字符串进行拼接的方式，一定要注意引用的EntityManager的类

package com.demo.dao.imp;

import com.demo.dao.IFindByStr;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.persistence.EntityManager;
import java.math.BigInteger;
import java.util.List;

@Service
public class FindByStr implements IFindByStr {
    @Autowired
    private EntityManager entityManager;
    @Override
    public List findStr(){
        //查询语句string拼接结果
        StringBuffer sql = new StringBuffer("SELECT * " +"FROM cst_customer " +"where 1=1 ");
        //转换数据格式
        String sqlStr = sql.toString();
        //字符串传入到Query中
        javax.persistence.Query query = entityManager.createNativeQuery(sqlStr);
        //查询数据库
        List list = query.getResultList();
        return list;
    }
}      

下边就是贴的代码了

整体的结构是这样的，两个接口，一个实体类，一个实现类

package com.demo.dao;

import java.util.List;


public interface IFindByStr {
    //字符串拼接sql
    public List findStr();
}      

package com.demo.dao;

import com.demo.domain.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;

import java.math.BigInteger;
import java.util.List;

public interface CustomerDao extends JpaRepository<Customer,Long> ,JpaSpecificationExecutor<Customer> {

    @Query(value="from Customer where custName = ?1")
    public Customer findJpql(String custName);


    /**
     *  sql  ：update cst_customer set cust_name = ? where cust_id = ?
     *  jpql : update Customer set custName = ? where custId = ?
     */
    @Query(value = " update Customer set custName = ?2 where custId = ?1 ")
    @Modifying
    public void updateCustomer(long custId, String custName);

    @Query(value="select * from cst_customer where cust_name like ?1",nativeQuery = true)
    public List<Object [] > findSql(String name);


    public Customer findByCustName(String custName);

    public List<Customer> findByCustNameLike(String custName);

    //使用客户名称模糊匹配和客户所属行业精准匹配的查询
    public Customer findByCustNameLikeAndCustIndustry(String custName, String custIndustry);



}      

package com.demo.domain;

import javax.persistence.*;

@Entity
@Table(name="cst_customer")
public class Customer {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="cust_id")
    private Long custId;
    @Column(name="cust_address")
    private String custAddress;
    @Column(name="cust_industry")
    private String custIndustry;
    @Column(name="cust_level")
    private String custLevel;
    @Column(name="cust_name")
    private String custName;
    @Column(name="cust_phone")
    private String custPhone;
    @Column(name="cust_source")
    private String custSource;

    public Long getCustId() {
        return custId;
    }

    public void setCustId(Long custId) {
        this.custId = custId;
    }

    public String getCustAddress() {
        return custAddress;
    }

    public void setCustAddress(String custAddress) {
        this.custAddress = custAddress;
    }

    public String getCustIndustry() {
        return custIndustry;
    }

    public void setCustIndustry(String custIndustry) {
        this.custIndustry = custIndustry;
    }

    public String getCustLevel() {
        return custLevel;
    }

    public void setCustLevel(String custLevel) {
        this.custLevel = custLevel;
    }

    public String getCustName() {
        return custName;
    }

    public void setCustName(String custName) {
        this.custName = custName;
    }

    public String getCustPhone() {
        return custPhone;
    }

    public void setCustPhone(String custPhone) {
        this.custPhone = custPhone;
    }

    public String getCustSource() {
        return custSource;
    }

    public void setCustSource(String custSource) {
        this.custSource = custSource;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "custId=" + custId +
                ", custAddress='" + custAddress + '\'' +
                ", custIndustry='" + custIndustry + '\'' +
                ", custLevel='" + custLevel + '\'' +
                ", custName='" + custName + '\'' +
                ", custPhone='" + custPhone + '\'' +
                ", custSource='" + custSource + '\'' +
                '}';
    }
}      

结束