目录
[一 介绍](#一 介绍)
[二 Mybatis的入门](#二 Mybatis的入门)
[2.1 快速入门](#2.1 快速入门)
[2.1.1 准备SpringBoot工程](#2.1.1 准备SpringBoot工程)
[2.1.2 创建数据库mybatis以及对应库表user](#2.1.2 创建数据库mybatis以及对应库表user)
[2.1.3 创建User实体类](#2.1.3 创建User实体类)
[2.1.4 配置application.properties数据库连接信息](#2.1.4 配置application.properties数据库连接信息)
[2.1.5 编写sql语句(注解方式)](#2.1.5 编写sql语句(注解方式))
[2.1.6 测试运行](#2.1.6 测试运行)
[2.1.7 配置SQL提示](#2.1.7 配置SQL提示)
[2.2 JDBC介绍(了解)](#2.2 JDBC介绍(了解))
[2.2.1 JDBC 介绍](#2.2.1 JDBC 介绍)
[2.2.2 jdbc与Mybatis对比](#2.2.2 jdbc与Mybatis对比)
[2.3 数据库连接池(了解)](#2.3 数据库连接池(了解))
[2.3.1 概念](#2.3.1 概念)
[2.3.2 mybatis切换Druid(德鲁伊)连接池](#2.3.2 mybatis切换Druid(德鲁伊)连接池)
[2.3.3 总结](#2.3.3 总结)
[2.4 lombok](#2.4 lombok)
[三 Mybatis的基础操作](#三 Mybatis的基础操作)
[3.1 准备工作](#3.1 准备工作)
[3.1.1 数据脚本在mybatis表执行脚本](#3.1.1 数据脚本在mybatis表执行脚本)
[3.1.2 创建一个springboot项目](#3.1.2 创建一个springboot项目)
[3.1.3 application.properties配置](#3.1.3 application.properties配置)
[3.1.4 创建对应实体类Emp](#3.1.4 创建对应实体类Emp)
[3.1.5 准备Mapper接口EmpMapper](#3.1.5 准备Mapper接口EmpMapper)
[3.2 日志输出](#3.2 日志输出)
[3.2.1 性能高](#3.2.1 性能高)
[3.2.2 更安全](#3.2.2 更安全)
[3.3 删除](#3.3 删除)
[3.3.1 EmpMapper接口添加 删除方法](#3.3.1 EmpMapper接口添加 删除方法)
[3.3.2 新增测试方法](#3.3.2 新增测试方法)
[3.4 新增](#3.4 新增)
[3.4.1 EmpMapper接口添加 新增方法](#3.4.1 EmpMapper接口添加 新增方法)
[3.4.2 新增测试方法](#3.4.2 新增测试方法)
[3.4.3 主键返回](#3.4.3 主键返回)
[3.4.4 总结](#3.4.4 总结)
[3.5 更新](#3.5 更新)
[3.5.1 EmpMapper接口添加 更新方法](#3.5.1 EmpMapper接口添加 更新方法)
[3.5.2 新增测试方法](#3.5.2 新增测试方法)
[3.6 查询](#3.6 查询)
[3.6.1 EmpMapper接口添加 查询方法](#3.6.1 EmpMapper接口添加 查询方法)
[3.6.2 新增测试方法](#3.6.2 新增测试方法)
[3.6.3 数据封装](#3.6.3 数据封装)
[3.6.3.1 方案一 (不推荐):当数据库字段与实体类字段不一致时取别名](#3.6.3.1 方案一 (不推荐):当数据库字段与实体类字段不一致时取别名)
[3.6.3.2 方案二(不推荐) :通过@Results, @Result注解手动映射封装](#3.6.3.2 方案二(不推荐) :通过@Results, @Result注解手动映射封装)
[3.6.3.3 方案三(推荐):开启mybatis的驼峰命名自动映射开关](#3.6.3.3 方案三(推荐):开启mybatis的驼峰命名自动映射开关)
[3.7 查询(条件查询)](#3.7 查询(条件查询))
[3.7.1 EmpMapper接口添加 条件查询方法](#3.7.1 EmpMapper接口添加 条件查询方法)
[3.7.2 新增测试方法](#3.7.2 新增测试方法)
[3.7.3 使用concat解决使用'%name}%'问题](#3.7.3 使用concat解决使用'%name}%'问题)
[四 XML映射文件](#四 XML映射文件)
[4.1 XML映射规范](#4.1 XML映射规范)
[4.1.1 第一步:](#4.1.1 第一步:)
[4.1.2 第二步:编辑](#4.1.2 第二步:编辑)
[4.1.3 第三步](#4.1.3 第三步)
[4.1.4 验证](#4.1.4 验证)
[4.2 mybatisx插件](#4.2 mybatisx插件)
[4.3 总结](#4.3 总结)
[五 Mybatis的动态SQL](#五 Mybatis的动态SQL)
[5.1.1 优化EmpMapper.xml](#5.1.1 优化EmpMapper.xml)
[5.1.2 案例](#5.1.2 案例)
[5.1.2.1 优化EmpMapper 新增一个方法update2](#5.1.2.1 优化EmpMapper 新增一个方法update2)
[5.1.2.2 EmpMpapper.xml新增一个update2的sql](#5.1.2.2 EmpMpapper.xml新增一个update2的sql)
[5.1.2.3 新增测试方法testUpdate2测试](#5.1.2.3 新增测试方法testUpdate2测试)
[编辑5.1.3 总结](#编辑5.1.3 总结)
[5.2.1 优化EmpMapper 新增一个方法deleteByIds](#5.2.1 优化EmpMapper 新增一个方法deleteByIds)
[5.2.2 EmpMpapper.xml新增一个deleteByIds的sql](#5.2.2 EmpMpapper.xml新增一个deleteByIds的sql)
[5.2.3 新增测试方法testDeleteByids](#5.2.3 新增测试方法testDeleteByids)
[5.2.4 总结](#5.2.4 总结)
[5.3.1 EmpMpapper.xml新增sql 标签优化list2 include标签](#5.3.1 EmpMpapper.xml新增sql 标签优化list2 include标签)
[5.3.2 执行测试方法testList2](#5.3.2 执行测试方法testList2)
[5.4 总结](#5.4 总结)
前言:Mybatis数据持久层,进行数据库操作,增删改查 ,动态sql
一 介绍
二 Mybatis的入门
2.1 快速入门
案例
2.1.1 准备SpringBoot工程
2.1.2 创建数据库mybatis以及对应库表user
java
create database mybatis;
sql
create table user(
id int unsigned primary key auto_increment comment 'ID',
name varchar(100) comment '姓名',
age tinyint unsigned comment '年龄',
gender tinyint unsigned comment '性别, 1:男, 2:女',
phone varchar(11) comment '手机号'
) comment '用户表';
insert into user(id, name, age, gender, phone) VALUES (null,'白眉鹰王',55,'1','18800000000');
insert into user(id, name, age, gender, phone) VALUES (null,'金毛狮王',45,'1','18800000001');
insert into user(id, name, age, gender, phone) VALUES (null,'青翼蝠王',38,'1','18800000002');
insert into user(id, name, age, gender, phone) VALUES (null,'紫衫龙王',42,'2','18800000003');
insert into user(id, name, age, gender, phone) VALUES (null,'光明左使',37,'1','18800000004');
insert into user(id, name, age, gender, phone) VALUES (null,'光明右使',48,'1','18800000005');
2.1.3 创建User实体类
java
package com.runa.pojo;
public class User {
private Integer id;
private String name;
private Short age;
private Short gender;
private String phone;
public User() {
}
public User(Integer id, String name, Short age, Short gender, String phone) {
this.id = id;
this.name = name;
this.age = age;
this.gender = gender;
this.phone = phone;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Short getAge() {
return age;
}
public void setAge(Short age) {
this.age = age;
}
public Short getGender() {
return gender;
}
public void setGender(Short gender) {
this.gender = gender;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", gender=" + gender +
", phone='" + phone + '\'' +
'}';
}
}
2.1.4 配置application.properties数据库连接信息
XML
# 配置数据库连接信息
#驱动类名称
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#数据库连接的url
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis
#连接数据库的用户名
spring.datasource.username=root
#连接数据库的密码
spring.datasource.password=1234
java
package com.runa.pojo;
public class User {
private Integer id;
private String name;
private Short age;
private Short gender;
private String phone;
public User(Integer id, String name, Short age, Short gender, String phone) {
this.id = id;
this.name = name;
this.age = age;
this.gender = gender;
this.phone = phone;
}
public User() {
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Short getAge() {
return age;
}
public void setAge(Short age) {
this.age = age;
}
public Short getGender() {
return gender;
}
public void setGender(Short gender) {
this.gender = gender;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", gender=" + gender +
", phone='" + phone + '\'' +
'}';
}
}
2.1.5 编写sql语句(注解方式)
java
package com.runa.mapper;
import com.runa.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import java.util.List;
@Mapper // 运行时,会自动生成该接口的实现类对象(代理对象),并且将改对象交给IOC容器管理
public interface UserMapper {
// 查询全部用户信息
@Select("select * from user")
public List<User> list();
}
2.1.6 测试运行
java
package com.runa;
import com.runa.mapper.UserMapper;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
@Autowired // 注入
private UserMapper userMapper;
@Test
public void testListUser() {
List<User> userList = userMapper.list();
userList.stream().forEach(user -> {
System.out.println(user);
});
}
// @Test
// void contextLoads() {
// }
}
2.1.7 配置SQL提示
设置好,还不行的话(删除其他数据库连接,刷新数据库连接),重启IEDA
2.2 JDBC介绍(了解)
2.2.1 JDBC 介绍
java
@Test
public void testJdbc() throws Exception {
//1 注册驱动
Class.forName("com.mysql.cj.jdbc.Driver");
// 2 获取连接对象
String url = "jdbc:mysql://localhost:3306/mybatis";
String username = "root";
String password = "runa#2050";
Connection connection = DriverManager.getConnection(url, username, password);
// 3 获取执行sql的对象statement,执行sql 返回结果
String sql = "select * from user";
Statement statement = null;
statement = connection.createStatement();
ResultSet resultSet = null;
resultSet = statement.executeQuery(sql);
// 4 封装结果数据
List<User> userList = new ArrayList<>();
while (resultSet.next()) {
int id = resultSet.getInt("id");
String name = resultSet.getString("name");
short age = resultSet.getShort("age");
short gender = resultSet.getShort("gender");
String phone = resultSet.getString("phone");
User user = new User(id, name, age, gender, phone);
userList.add(user);
}
// 5 释放资源
statement.close();
connection.close();
userList.stream().forEach(user -> {
System.out.println(user);
});
}
2.2.2 jdbc与Mybatis对比
2.3 数据库连接池(了解)
2.3.1 概念
2.3.2 mybatis切换Druid(德鲁伊)连接池
我没有配置成功
2.3.3 总结
2.4 lombok
添加依赖
XML
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
修改实体类User
XML
package com.runa.pojo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
private Integer id;
private String name;
private Short age;
private Short gender;
private String phone;
}
三 Mybatis的基础操作
3.1 准备工作
3.1.1 数据脚本在mybatis表执行脚本
sql
-- 部门管理
create table dept(
id int unsigned primary key auto_increment comment '主键ID',
name varchar(10) not null unique comment '部门名称',
create_time datetime not null comment '创建时间',
update_time datetime not null comment '修改时间'
) comment '部门表';
insert into dept (id, name, create_time, update_time) values(1,'学工部',now(),now()),(2,'教研部',now(),now()),(3,'咨询部',now(),now()), (4,'就业部',now(),now()),(5,'人事部',now(),now());
-- 员工管理
create table emp (
id int unsigned primary key auto_increment comment 'ID',
username varchar(20) not null unique comment '用户名',
password varchar(32) default '123456' comment '密码',
name varchar(10) not null comment '姓名',
gender tinyint unsigned not null comment '性别, 说明: 1 男, 2 女',
image varchar(300) comment '图像',
job tinyint unsigned comment '职位, 说明: 1 班主任,2 讲师, 3 学工主管, 4 教研主管, 5 咨询师',
entrydate date comment '入职时间',
dept_id int unsigned comment '部门ID',
create_time datetime not null comment '创建时间',
update_time datetime not null comment '修改时间'
) comment '员工表';
INSERT INTO emp
(id, username, password, name, gender, image, job, entrydate,dept_id, create_time, update_time) VALUES
(1,'jinyong','123456','金庸',1,'1.jpg',4,'2000-01-01',2,now(),now()),
(2,'zhangwuji','123456','张无忌',1,'2.jpg',2,'2015-01-01',2,now(),now()),
(3,'yangxiao','123456','杨逍',1,'3.jpg',2,'2008-05-01',2,now(),now()),
(4,'weiyixiao','123456','韦一笑',1,'4.jpg',2,'2007-01-01',2,now(),now()),
(5,'changyuchun','123456','常遇春',1,'5.jpg',2,'2012-12-05',2,now(),now()),
(6,'xiaozhao','123456','小昭',2,'6.jpg',3,'2013-09-05',1,now(),now()),
(7,'jixiaofu','123456','纪晓芙',2,'7.jpg',1,'2005-08-01',1,now(),now()),
(8,'zhouzhiruo','123456','周芷若',2,'8.jpg',1,'2014-11-09',1,now(),now()),
(9,'dingminjun','123456','丁敏君',2,'9.jpg',1,'2011-03-11',1,now(),now()),
(10,'zhaomin','123456','赵敏',2,'10.jpg',1,'2013-09-05',1,now(),now()),
(11,'luzhangke','123456','鹿杖客',1,'11.jpg',5,'2007-02-01',3,now(),now()),
(12,'hebiweng','123456','鹤笔翁',1,'12.jpg',5,'2008-08-18',3,now(),now()),
(13,'fangdongbai','123456','方东白',1,'13.jpg',5,'2012-11-01',3,now(),now()),
(14,'zhangsanfeng','123456','张三丰',1,'14.jpg',2,'2002-08-01',2,now(),now()),
(15,'yulianzhou','123456','俞莲舟',1,'15.jpg',2,'2011-05-01',2,now(),now()),
(16,'songyuanqiao','123456','宋远桥',1,'16.jpg',2,'2010-01-01',2,now(),now()),
(17,'chenyouliang','123456','陈友谅',1,'17.jpg',NULL,'2015-03-21',NULL,now(),now());
3.1.2 创建一个springboot项目
引入起步依赖mybatis、mysql驱动、lombok
3.1.3 application.properties配置
指定mybatis输出日志的位置。输出控制台
XML
# 配置数据库连接
# 驱动类名称
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
# 连接数据库的url
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis
#连接数据库用户名
spring.datasource.username=root
# 连接数据库密码
spring.datasource.password=runa#2050
# 指定mybatis输出日志的位置。输出控制台
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
3.1.4 创建对应实体类Emp
java
package com.runa.pojo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.time.LocalDate;
import java.time.LocalDateTime;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Emp {
private Integer id;
private String username;
private String password;
private String name;
private Short gender;
private String image;
private Short job;
private LocalDate entrydate;
private Integer deptId;
private LocalDateTime createTime;
private LocalDateTime updateTime;
}
3.1.5 准备Mapper接口EmpMapper
java
package com.runa.mapper;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface EmpMapper {
}
3.2 日志输出
3.2.1 性能高
3.2.2 更安全
3.2.3 总结 使用#
3.3 删除
3.3.1 EmpMapper接口添加 删除方法
java
package com.runa.mapper;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface EmpMapper {
// 根据id删除数据
@Delete("delete from emp where id = #{id}")
public void delete(Integer id);
}
3.3.2 新增测试方法
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
@Autowired //注入
private EmpMapper empMapper;
@Test
public void testDelete(){
empMapper.delete(17);
}
}
改造一下获取返回值
java
package com.runa.mapper;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface EmpMapper {
// 根据id删除数据
// @Delete("delete from emp where id = #{id}")
// public void delete(Integer id);
// 根据id删除数据,并获取返回值
@Delete("delete from emp where id = #{id}")
public int delete(Integer id);
}
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
// @Autowired // 注入
// private UserMapper userMapper;
@Autowired //注入
private EmpMapper empMapper;
// @Test
// public void testListUser() {
// List<User> userList = userMapper.list();
// userList.stream().forEach(user -> {
// System.out.println(user);
// });
// }
// @Test
// public void testDelete(){
// empMapper.delete(17);
//
// }
@Test // 获取返回值
public void testDelete(){
int id = empMapper.delete(16);
System.out.println(id);
}
}
返回 1表示删除成功,0 是失败
3.4 新增
3.4.1 EmpMapper接口添加 新增方法
java
package com.runa.mapper;
import com.runa.pojo.Emp;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface EmpMapper {
// 根据id删除数据
@Delete("delete from emp where id = #{id}")
public void delete(Integer id);
// 根据id删除数据,并获取返回值
// @Delete("delete from emp where id = #{id}")
// public int delete(Integer id);
// 新增员工
@Insert("insert into emp\n" +
"(username, name, gender, image, job, entrydate,dept_id, create_time, update_time)" +
" VALUES(#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")
public void insert(Emp emp);
}
3.4.2 新增测试方法
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.Emp;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
// @Autowired // 注入
// private UserMapper userMapper;
@Autowired //注入
private EmpMapper empMapper;
// @Test
// public void testListUser() {
// List<User> userList = userMapper.list();
// userList.stream().forEach(user -> {
// System.out.println(user);
// });
// }
@Test
public void testDelete(){
empMapper.delete(17);
}
// @Test // 获取返回值
// public void testDelete(){
// int id = empMapper.delete(16);
// System.out.println(id);
// }
@Test
public void testInsert(){
// 构造员工对象
Emp emp = new Emp();
emp.setUsername("Bocai");
emp.setName("菠菜");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setCreateTime(LocalDateTime.now());
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行新增员工的信息操作
empMapper.insert(emp);
}
}
3.4.3 主键返回
3.4.4 总结
3.5 更新
3.5.1 EmpMapper接口添加 更新方法
java
package com.runa.mapper;
import com.runa.pojo.Emp;
import org.apache.ibatis.annotations.*;
@Mapper
public interface EmpMapper {
// 根据id删除数据
@Delete("delete from emp where id = #{id}")
public void delete(Integer id);
// 根据id删除数据,并获取返回值
// @Delete("delete from emp where id = #{id}")
// public int delete(Integer id);
// 新增员工
@Options(useGeneratedKeys = true, keyProperty = "id")
@Insert("insert into emp" +
"(username, name, gender, image, job, entrydate,dept_id, create_time, update_time)" +
" VALUES(#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")
public void insert(Emp emp);
// 更新员工信息
@Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}, " +
"job = #{job}, entrydate = #{entrydate},dept_id = #{deptId}, update_time = #{updateTime} where id = #{id}")
public void update(Emp emp);
}
3.5.2 新增测试方法
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.Emp;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
// @Autowired // 注入
// private UserMapper userMapper;
@Autowired //注入
private EmpMapper empMapper;
// @Test
// public void testListUser() {
// List<User> userList = userMapper.list();
// userList.stream().forEach(user -> {
// System.out.println(user);
// });
// }
@Test
public void testDelete(){
empMapper.delete(17);
}
// @Test // 获取返回值
// public void testDelete(){
// int id = empMapper.delete(16);
// System.out.println(id);
// }
@Test
public void testInsert(){
// 构造员工对象
Emp emp = new Emp();
emp.setUsername("Bocai1");
emp.setName("菠菜1");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setCreateTime(LocalDateTime.now());
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行新增员工的信息操作
empMapper.insert(emp);
System.out.println(emp.getId());
}
@Test
public void testUpdate(){
// 构造员工对象
Emp emp = new Emp();
emp.setId(19);
emp.setUsername("Spring");
emp.setName("春天的菠菜");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行更新员工的信息操作
empMapper.update(emp);
}
}
3.6 查询
3.6.1 EmpMapper接口添加 查询方法
java
package com.runa.mapper;
import com.runa.pojo.Emp;
import org.apache.ibatis.annotations.*;
@Mapper
public interface EmpMapper {
// 根据id删除数据
@Delete("delete from emp where id = #{id}")
public void delete(Integer id);
// 根据id删除数据,并获取返回值
// @Delete("delete from emp where id = #{id}")
// public int delete(Integer id);
// 新增员工
@Options(useGeneratedKeys = true, keyProperty = "id")
@Insert("insert into emp" +
"(username, name, gender, image, job, entrydate,dept_id, create_time, update_time)" +
" VALUES(#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")
public void insert(Emp emp);
// 更新员工信息
@Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}, " +
"job = #{job}, entrydate = #{entrydate},dept_id = #{deptId}, update_time = #{updateTime} where id = #{id}")
public void update(Emp emp);
// 根据ID查询员工
@Select("select * from emp where id = #{id}")
public Emp getById(Integer id);
}
3.6.2 新增测试方法
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.Emp;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
// @Autowired // 注入
// private UserMapper userMapper;
@Autowired //注入
private EmpMapper empMapper;
// @Test
// public void testListUser() {
// List<User> userList = userMapper.list();
// userList.stream().forEach(user -> {
// System.out.println(user);
// });
// }
@Test
public void testDelete(){
empMapper.delete(17);
}
// @Test // 获取返回值
// public void testDelete(){
// int id = empMapper.delete(16);
// System.out.println(id);
// }
// 测试新增
@Test
public void testInsert(){
// 构造员工对象
Emp emp = new Emp();
emp.setUsername("Bocai1");
emp.setName("菠菜1");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setCreateTime(LocalDateTime.now());
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行新增员工的信息操作
empMapper.insert(emp);
System.out.println(emp.getId());
}
// 测试更新
@Test
public void testUpdate(){
// 构造员工对象
Emp emp = new Emp();
emp.setId(19);
emp.setUsername("Spring");
emp.setName("春天的菠菜");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行更新员工的信息操作
empMapper.update(emp);
}
// 根据员工ID查询员工
@Test
public void testGetById(){
Emp emp = empMapper.getById(19);
System.out.println(emp);
}
}
3.6.3 数据封装
3.6.3.1 方案一 (不推荐):当数据库字段与实体类字段不一致时取别名
修改Empmapper接口类
java
// 根据ID查询员工
// @Select("select * from emp where id = #{id}")
// public Emp getById(Integer id);
// 根据ID查询员工,取别名方案
@Select("select id,id, username, password, name, gender, image, job, entrydate, dept_id deptId, create_time createTime, update_time updateTime from emp where id = #{id}")
public Emp getById(Integer id);
3.6.3.2 方案二(不推荐) :通过@Results, @Result注解手动映射封装
java
// 根据ID查询员工
// @Select("select * from emp where id = #{id}")
// public Emp getById(Integer id);
// 根据ID查询员工,方案一:取别名方案
// @Select("select id,id, username, password, name, gender, image, job, entrydate, dept_id deptId, create_time createTime, update_time updateTime from emp where id = #{id}")
// public Emp getById(Integer id);
// 根据ID查询员工 方案二:通过@Results, @Result注解手动映射封装
@Results({
@Result(column = "dept_id", property = "deptId"),
@Result(column = "create_time", property = "createTime"),
@Result(column = "update_time", property = "updateTime")
})
@Select("select * from emp where id = #{id}")
public Emp getById(Integer id);
3.6.3.3 方案三(推荐):开启mybatis的驼峰命名自动映射开关
application.properties新增配置
java
# 配置数据库连接
# 驱动类名称
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
# 连接数据库的url
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis
#连接数据库用户名
spring.datasource.username=root
# 连接数据库密码
spring.datasource.password=runa#2050
# 指定mybatis输出日志的位置。输出控制台
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
# # 开启mybatis的驼峰命名自动映射开关
mybatis.configuration.map-underscore-to-camel-case=true
插曲:IDEA 的application.properties中文乱码,
配置前:
修改后:
3.7 查询(条件查询)
3.7.1 EmpMapper接口添加 条件查询方法
'%#{name}%' #{name} 不能出现在''里面所以改成$
java
package com.runa.mapper;
import com.runa.pojo.Emp;
import org.apache.ibatis.annotations.*;
import java.time.LocalDate;
import java.util.List;
@Mapper
public interface EmpMapper {
// 根据id删除数据
@Delete("delete from emp where id = #{id}")
public void delete(Integer id);
// 根据id删除数据,并获取返回值
// @Delete("delete from emp where id = #{id}")
// public int delete(Integer id);
// 新增员工
@Options(useGeneratedKeys = true, keyProperty = "id")
@Insert("insert into emp" +
"(username, name, gender, image, job, entrydate,dept_id, create_time, update_time)" +
" VALUES(#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")
public void insert(Emp emp);
// 更新员工信息
@Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}, " +
"job = #{job}, entrydate = #{entrydate},dept_id = #{deptId}, update_time = #{updateTime} where id = #{id}")
public void update(Emp emp);
// 根据ID查询员工
@Select("select * from emp where id = #{id}")
public Emp getById(Integer id);
// 根据ID查询员工, (不推荐)方案一:取别名方案
// @Select("select id,id, username, password, name, gender, image, job, entrydate, dept_id deptId, create_time createTime, update_time updateTime from emp where id = #{id}")
// public Emp getById(Integer id);
// 根据ID查询员工 (不推荐)方案二:通过@Results, @Result注解手动映射封装
// @Results({
// @Result(column = "dept_id", property = "deptId"),
// @Result(column = "create_time", property = "createTime"),
// @Result(column = "update_time", property = "updateTime")
// })
// @Select("select * from emp where id = #{id}")
// public Emp getById(Integer id);
// 条件查询员工 '%#{name}%' #{name} 不能出现在''里面所以改成$
@Select("select * from emp where name like '%${name}%'and gender = #{gender} and entrydate between #{begin} and #{end} order by update_time desc ")
public List<Emp> list(String name, Short gender, LocalDate begin, LocalDate end);
}
3.7.2 新增测试方法
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.Emp;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
// @Autowired // 注入
// private UserMapper userMapper;
@Autowired //注入
private EmpMapper empMapper;
// @Test
// public void testListUser() {
// List<User> userList = userMapper.list();
// userList.stream().forEach(user -> {
// System.out.println(user);
// });
// }
@Test
public void testDelete(){
empMapper.delete(17);
}
// @Test // 获取返回值
// public void testDelete(){
// int id = empMapper.delete(16);
// System.out.println(id);
// }
// 测试新增
@Test
public void testInsert(){
// 构造员工对象
Emp emp = new Emp();
emp.setUsername("Bocai1");
emp.setName("菠菜1");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setCreateTime(LocalDateTime.now());
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行新增员工的信息操作
empMapper.insert(emp);
System.out.println(emp.getId());
}
// 测试更新
@Test
public void testUpdate(){
// 构造员工对象
Emp emp = new Emp();
emp.setId(19);
emp.setUsername("Spring");
emp.setName("春天的菠菜");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行更新员工的信息操作
empMapper.update(emp);
}
// 根据员工ID查询员工
@Test
public void testGetById(){
Emp emp = empMapper.getById(19);
System.out.println(emp);
}
// 条件查询
@Test
public void testList(){
List<Emp> listEmp = empMapper.list("张", (short) 1, LocalDate.of(2010, 1, 1), LocalDate.of(2020, 1, 1));
System.out.println(listEmp);
}
}
3.7.3 使用concat解决使用'%$name}%'问题
修改EmpMapper接口
java
package com.runa.mapper;
import com.runa.pojo.Emp;
import org.apache.ibatis.annotations.*;
import java.time.LocalDate;
import java.util.List;
@Mapper
public interface EmpMapper {
// 根据id删除数据
@Delete("delete from emp where id = #{id}")
public void delete(Integer id);
// 根据id删除数据,并获取返回值
// @Delete("delete from emp where id = #{id}")
// public int delete(Integer id);
// 新增员工
@Options(useGeneratedKeys = true, keyProperty = "id")
@Insert("insert into emp" +
"(username, name, gender, image, job, entrydate,dept_id, create_time, update_time)" +
" VALUES(#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")
public void insert(Emp emp);
// 更新员工信息
@Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}, " +
"job = #{job}, entrydate = #{entrydate},dept_id = #{deptId}, update_time = #{updateTime} where id = #{id}")
public void update(Emp emp);
// 根据ID查询员工
@Select("select * from emp where id = #{id}")
public Emp getById(Integer id);
// 根据ID查询员工, (不推荐)方案一:取别名方案
// @Select("select id,id, username, password, name, gender, image, job, entrydate, dept_id deptId, create_time createTime, update_time updateTime from emp where id = #{id}")
// public Emp getById(Integer id);
// 根据ID查询员工 (不推荐)方案二:通过@Results, @Result注解手动映射封装
// @Results({
// @Result(column = "dept_id", property = "deptId"),
// @Result(column = "create_time", property = "createTime"),
// @Result(column = "update_time", property = "updateTime")
// })
// @Select("select * from emp where id = #{id}")
// public Emp getById(Integer id);
// 条件查询员工 '%#{name}%' #{name} 不能出现在''里面所以改成$
// @Select("select * from emp where name like '%${name}%'and gender = #{gender} and entrydate between #{begin} and #{end} order by update_time desc ")
// public List<Emp> list(String name, Short gender, LocalDate begin, LocalDate end);
// 条件查询员工 使用concat解决 '%${name}%'
@Select("select * from emp where name like concat('%', #{name}, '%')and gender = #{gender} and entrydate between #{begin} and #{end} order by update_time desc ")
public List<Emp> list(String name, Short gender, LocalDate begin, LocalDate end);
}
以下图片可忽略
四 XML映射文件
4.1 XML映射规范
4.1.1 第一步:
EmpMapper.xml文件如下:
XML
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper>
</mapper>
4.1.2 第二步:
XML
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.runa.mapper.EmpMapper">
</mapper>
4.1.3 第三步
resultType : 表示单条记录所封装的类型
XML
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.runa.mapper.EmpMapper">
<!--id EmpMapper 方法名 resultType : 表示单条记录所封装的类型 -->
<select id="list2" resultType="com.runa.pojo.Emp">
select * from emp where name like concat('%', #{name}, '%')and gender = #{gender} and entrydate between #{begin} and #{end} order by update_time desc
</select>
</mapper>
4.1.4 验证
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.Emp;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
// @Autowired // 注入
// private UserMapper userMapper;
@Autowired //注入
private EmpMapper empMapper;
// @Test
// public void testListUser() {
// List<User> userList = userMapper.list();
// userList.stream().forEach(user -> {
// System.out.println(user);
// });
// }
@Test
public void testDelete(){
empMapper.delete(17);
}
// @Test // 获取返回值
// public void testDelete(){
// int id = empMapper.delete(16);
// System.out.println(id);
// }
// 测试新增
@Test
public void testInsert(){
// 构造员工对象
Emp emp = new Emp();
emp.setUsername("Bocai1");
emp.setName("菠菜1");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setCreateTime(LocalDateTime.now());
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行新增员工的信息操作
empMapper.insert(emp);
System.out.println(emp.getId());
}
// 测试更新
@Test
public void testUpdate(){
// 构造员工对象
Emp emp = new Emp();
emp.setId(19);
emp.setUsername("Spring");
emp.setName("春天的菠菜");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行更新员工的信息操作
empMapper.update(emp);
}
// 根据员工ID查询员工
@Test
public void testGetById(){
Emp emp = empMapper.getById(19);
System.out.println(emp);
}
// 条件查询
@Test
public void testList(){
List<Emp> listEmp = empMapper.list("张", (short) 1, LocalDate.of(2010, 1, 1), LocalDate.of(2020, 1, 1));
System.out.println(listEmp);
}
// 条件查询 使用xml
@Test
public void testList2(){
List<Emp> listEmp = empMapper.list2("张", (short) 1, LocalDate.of(2010, 1, 1), LocalDate.of(2020, 1, 1));
System.out.println(listEmp);
}
}
4.2 mybatisx插件
快速定位
4.3 总结
五 Mybatis的动态SQL
5.1 <if>
5.1.1 优化EmpMapper.xml
XML
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.runa.mapper.EmpMapper">
<!--id EmpMapper 方法名 resultType : 表示单条记录所封装的类型 -->
<select id="list2" resultType="com.runa.pojo.Emp">
select *
from emp
<where>
<if test= "name != null">
name like concat('%', #{name}, '%')
</if>
<if test= "gender != null">
and gender = #{gender}
</if>
<if test= "begin != null and end != null">
and entrydate between #{begin} and #{end}
</if>
order by update_time desc
</where>
</select>
</mapper>
注意:<where></where> 会针对多条件查询过滤一些特有的and
5.1.2 案例
5.1.2.1 优化EmpMapper 新增一个方法update2
java
package com.runa.mapper;
import com.runa.pojo.Emp;
import org.apache.ibatis.annotations.*;
import java.time.LocalDate;
import java.util.List;
@Mapper
public interface EmpMapper {
// 根据id删除数据
@Delete("delete from emp where id = #{id}")
public void delete(Integer id);
// 根据id删除数据,并获取返回值
// @Delete("delete from emp where id = #{id}")
// public int delete(Integer id);
// 新增员工
@Options(useGeneratedKeys = true, keyProperty = "id")
@Insert("insert into emp" +
"(username, name, gender, image, job, entrydate,dept_id, create_time, update_time)" +
" VALUES(#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")
public void insert(Emp emp);
// 更新员工信息
@Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}, " +
"job = #{job}, entrydate = #{entrydate},dept_id = #{deptId}, update_time = #{updateTime} where id = #{id}")
public void update(Emp emp);
// 根据ID查询员工
@Select("select * from emp where id = #{id}")
public Emp getById(Integer id);
// 根据ID查询员工, (不推荐)方案一:取别名方案
// @Select("select id,id, username, password, name, gender, image, job, entrydate, dept_id deptId, create_time createTime, update_time updateTime from emp where id = #{id}")
// public Emp getById(Integer id);
// 根据ID查询员工 (不推荐)方案二:通过@Results, @Result注解手动映射封装
// @Results({
// @Result(column = "dept_id", property = "deptId"),
// @Result(column = "create_time", property = "createTime"),
// @Result(column = "update_time", property = "updateTime")
// })
// @Select("select * from emp where id = #{id}")
// public Emp getById(Integer id);
// 条件查询员工 '%#{name}%' #{name} 不能出现在''里面所以改成$
// @Select("select * from emp where name like '%${name}%'and gender = #{gender} and entrydate between #{begin} and #{end} order by update_time desc ")
// public List<Emp> list(String name, Short gender, LocalDate begin, LocalDate end);
// 条件查询员工 使用concat解决 '%${name}%'
@Select("select * from emp where name like concat('%', #{name}, '%')and gender = #{gender} and entrydate between #{begin} and #{end} order by update_time desc ")
public List<Emp> list(String name, Short gender, LocalDate begin, LocalDate end);
// 条件查询员工使用xml方式
public List<Emp> list2(String name, Short gender, LocalDate begin, LocalDate end);
// 更新员工信息使用xml方式 使用<if>,使用动态sql方式
public void update2(Emp emp);
}
5.1.2.2 EmpMpapper.xml新增一个update2的sql
这里也使用了<set></set>标签
XML
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.runa.mapper.EmpMapper">
<!--id EmpMapper 方法名 resultType : 表示单条记录所封装的类型 -->
<select id="list2" resultType="com.runa.pojo.Emp">
select *
from emp
<where>
<if test="name != null">
name like concat('%', #{name}, '%')
</if>
<if test="gender != null">
and gender = #{gender}
</if>
<if test="begin != null and end != null">
and entrydate between #{begin} and #{end}
</if>
order by update_time desc
</where>
</select>
<!-- 动态更新员工-->
<update id="update2">
update emp
<set>
<if test="username != null">username = #{username},</if>
<if test="name != null">name= #{name},</if>
<if test="gender != null">gender = #{gender},</if>
<if test="image != null">image = #{image},</if>
<if test="job != null">job = #{job},</if>
<if test="entrydate != null">entrydate = #{entrydate},</if>
<if test="deptId != null">dept_id = #{deptId},</if>
<if test="updateTime != null">update_time = #{updateTime}</if>
</set>
where id=#{id}
</update>
</mapper>
5.1.2.3 新增测试方法testUpdate2测试
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.Emp;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
// @Autowired // 注入
// private UserMapper userMapper;
@Autowired //注入
private EmpMapper empMapper;
// @Test
// public void testListUser() {
// List<User> userList = userMapper.list();
// userList.stream().forEach(user -> {
// System.out.println(user);
// });
// }
@Test
public void testDelete(){
empMapper.delete(17);
}
// @Test // 获取返回值
// public void testDelete(){
// int id = empMapper.delete(16);
// System.out.println(id);
// }
// 测试新增
@Test
public void testInsert(){
// 构造员工对象
Emp emp = new Emp();
emp.setUsername("Bocai1");
emp.setName("菠菜1");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setCreateTime(LocalDateTime.now());
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行新增员工的信息操作
empMapper.insert(emp);
System.out.println(emp.getId());
}
// 测试更新
@Test
public void testUpdate(){
// 构造员工对象
Emp emp = new Emp();
emp.setId(19);
emp.setUsername("Spring");
emp.setName("春天的菠菜");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行更新员工的信息操作
empMapper.update(emp);
}
// 根据员工ID查询员工
@Test
public void testGetById(){
Emp emp = empMapper.getById(19);
System.out.println(emp);
}
// 条件查询
@Test
public void testList(){
List<Emp> listEmp = empMapper.list("张", (short) 1, LocalDate.of(2010, 1, 1), LocalDate.of(2020, 1, 1));
System.out.println(listEmp);
}
// 条件查询 使用xml
@Test
public void testList2(){
// List<Emp> listEmp = empMapper.list2("张", (short) 1, LocalDate.of(2010, 1, 1), LocalDate.of(2020, 1, 1));
List<Emp> listEmp = empMapper.list2("张", (short) 1, null, null);
System.out.println(listEmp);
}
// 测试更新,使用动态sql 更新id为18的员工username bocai2 更新为 name菠菜大哥 更新为 gender更新为 2
@Test
public void testUpdate2(){
// 构造员工对象
Emp emp = new Emp();
emp.setId(18);
emp.setUsername("bocai2");
emp.setName("菠菜大哥");
emp.setDeptId(2);
emp.setUpdateTime(LocalDateTime.now());
// 执行更新员工的信息操作
empMapper.update2(emp);
}
}
5.1.3 总结
5.2 <foreach>
5.2.1 优化EmpMapper 新增一个方法deleteByIds
java
package com.runa.mapper;
import com.runa.pojo.Emp;
import org.apache.ibatis.annotations.*;
import java.time.LocalDate;
import java.util.List;
@Mapper
public interface EmpMapper {
// 根据id删除数据
@Delete("delete from emp where id = #{id}")
public void delete(Integer id);
// 根据id删除数据,并获取返回值
// @Delete("delete from emp where id = #{id}")
// public int delete(Integer id);
// 新增员工
@Options(useGeneratedKeys = true, keyProperty = "id")
@Insert("insert into emp" +
"(username, name, gender, image, job, entrydate,dept_id, create_time, update_time)" +
" VALUES(#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")
public void insert(Emp emp);
// 更新员工信息
@Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}, " +
"job = #{job}, entrydate = #{entrydate},dept_id = #{deptId}, update_time = #{updateTime} where id = #{id}")
public void update(Emp emp);
// 根据ID查询员工
@Select("select * from emp where id = #{id}")
public Emp getById(Integer id);
// 批量删除员工
public void deleteByIds(List<Integer> ids);
// 根据ID查询员工, (不推荐)方案一:取别名方案
// @Select("select id,id, username, password, name, gender, image, job, entrydate, dept_id deptId, create_time createTime, update_time updateTime from emp where id = #{id}")
// public Emp getById(Integer id);
// 根据ID查询员工 (不推荐)方案二:通过@Results, @Result注解手动映射封装
// @Results({
// @Result(column = "dept_id", property = "deptId"),
// @Result(column = "create_time", property = "createTime"),
// @Result(column = "update_time", property = "updateTime")
// })
// @Select("select * from emp where id = #{id}")
// public Emp getById(Integer id);
// 条件查询员工 '%#{name}%' #{name} 不能出现在''里面所以改成$
// @Select("select * from emp where name like '%${name}%'and gender = #{gender} and entrydate between #{begin} and #{end} order by update_time desc ")
// public List<Emp> list(String name, Short gender, LocalDate begin, LocalDate end);
// 条件查询员工 使用concat解决 '%${name}%'
@Select("select * from emp where name like concat('%', #{name}, '%')and gender = #{gender} and entrydate between #{begin} and #{end} order by update_time desc ")
public List<Emp> list(String name, Short gender, LocalDate begin, LocalDate end);
// 条件查询员工使用xml方式
public List<Emp> list2(String name, Short gender, LocalDate begin, LocalDate end);
// 更新员工信息使用xml方式 使用<if>,使用动态sql方式
public void update2(Emp emp);
}
5.2.2 EmpMpapper.xml新增一个deleteByIds的sql
XML
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.runa.mapper.EmpMapper">
<!--id EmpMapper 方法名 resultType : 表示单条记录所封装的类型 -->
<select id="list2" resultType="com.runa.pojo.Emp">
select *
from emp
<where>
<if test="name != null">
name like concat('%', #{name}, '%')
</if>
<if test="gender != null">
and gender = #{gender}
</if>
<if test="begin != null and end != null">
and entrydate between #{begin} and #{end}
</if>
order by update_time desc
</where>
</select>
<!-- 动态更新员工-->
<update id="update2">
update emp
<set>
<if test="username != null">username = #{username},</if>
<if test="name != null">name= #{name},</if>
<if test="gender != null">gender = #{gender},</if>
<if test="image != null">image = #{image},</if>
<if test="job != null">job = #{job},</if>
<if test="entrydate != null">entrydate = #{entrydate},</if>
<if test="deptId != null">dept_id = #{deptId},</if>
<if test="updateTime != null">update_time = #{updateTime}</if>
</set>
where id=#{id}
</update>
<!-- 批量删除员工 (18,19,20)-->
<!--
collection : 要遍历的集合
item : 遍历出来的元素
separator : 分隔符
open :遍历开始前拼接的sql片段
close : 遍历结束后拼接的sql片段
)-->
<delete id="deleteByIds">
delete from emp where id in
<foreach collection="ids" item="id" separator="," open="(" close=")">
#{id}
</foreach>
</delete>
</mapper>
5.2.3 新增测试方法testDeleteByids
java
package com.runa;
import com.runa.mapper.EmpMapper;
import com.runa.mapper.UserMapper;
import com.runa.pojo.Emp;
import com.runa.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.sql.*;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {
// @Autowired // 注入
// private UserMapper userMapper;
@Autowired //注入
private EmpMapper empMapper;
// @Test
// public void testListUser() {
// List<User> userList = userMapper.list();
// userList.stream().forEach(user -> {
// System.out.println(user);
// });
// }
@Test
public void testDelete(){
empMapper.delete(17);
}
// @Test // 获取返回值
// public void testDelete(){
// int id = empMapper.delete(16);
// System.out.println(id);
// }
// 测试新增
@Test
public void testInsert(){
// 构造员工对象
Emp emp = new Emp();
emp.setUsername("Bocai1");
emp.setName("菠菜1");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setCreateTime(LocalDateTime.now());
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行新增员工的信息操作
empMapper.insert(emp);
System.out.println(emp.getId());
}
// 测试更新
@Test
public void testUpdate(){
// 构造员工对象
Emp emp = new Emp();
emp.setId(19);
emp.setUsername("Spring");
emp.setName("春天的菠菜");
emp.setImage("1.jpg");
emp.setGender((short)1);
emp.setJob((short)1);
emp.setEntrydate(LocalDate.of(2023, 2,27));
emp.setUpdateTime(LocalDateTime.now());
emp.setDeptId(1);
// 执行更新员工的信息操作
empMapper.update(emp);
}
// 根据员工ID查询员工
@Test
public void testGetById(){
Emp emp = empMapper.getById(19);
System.out.println(emp);
}
// 条件查询
@Test
public void testList(){
List<Emp> listEmp = empMapper.list("张", (short) 1, LocalDate.of(2010, 1, 1), LocalDate.of(2020, 1, 1));
System.out.println(listEmp);
}
// 条件查询 使用xml
@Test
public void testList2(){
// List<Emp> listEmp = empMapper.list2("张", (short) 1, LocalDate.of(2010, 1, 1), LocalDate.of(2020, 1, 1));
List<Emp> listEmp = empMapper.list2("张", (short) 1, null, null);
System.out.println(listEmp);
}
// 测试更新,使用动态sql 更新id为18的员工username bocai2 更新为 name菠菜大哥 更新为 gender更新为 2
@Test
public void testUpdate2(){
// 构造员工对象
Emp emp = new Emp();
emp.setId(18);
emp.setUsername("bocai2");
emp.setName("菠菜大哥");
emp.setDeptId(2);
emp.setUpdateTime(LocalDateTime.now());
// 执行更新员工的信息操作
empMapper.update2(emp);
}
// 批量删除员工 13 、 14、 15
@Test
public void testDeleteByids(){
List<Integer> ids = Arrays.asList(13, 14, 15);
empMapper.deleteByIds(ids);
}
}
5.2.4 总结
5.3 <sql><include>
存在大量重复的sql
解决方案
5.3.1 EmpMpapper.xml新增sql 标签优化list2 include标签
XML
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.runa.mapper.EmpMapper">
<sql id="commonSelect">
select id,id, username, password, name, gender, image, job, entrydate, dept_id deptId, create_time createTime, update_time updateTime from emp
</sql>
<!--id EmpMapper 方法名 resultType : 表示单条记录所封装的类型 -->
<select id="list2" resultType="com.runa.pojo.Emp">
<include refid="commonSelect"></include>
<where>
<if test="name != null">
name like concat('%', #{name}, '%')
</if>
<if test="gender != null">
and gender = #{gender}
</if>
<if test="begin != null and end != null">
and entrydate between #{begin} and #{end}
</if>
order by update_time desc
</where>
</select>
<!-- 动态更新员工-->
<update id="update2">
update emp
<set>
<if test="username != null">username = #{username},</if>
<if test="name != null">name= #{name},</if>
<if test="gender != null">gender = #{gender},</if>
<if test="image != null">image = #{image},</if>
<if test="job != null">job = #{job},</if>
<if test="entrydate != null">entrydate = #{entrydate},</if>
<if test="deptId != null">dept_id = #{deptId},</if>
<if test="updateTime != null">update_time = #{updateTime}</if>
</set>
where id=#{id}
</update>
<!-- 批量删除员工 (18,19,20)-->
<!--
collection : 要遍历的集合
item : 遍历出来的元素
separator : 分隔符
open :遍历开始前拼接的sql片段
close : 遍历结束后拼接的sql片段
)-->
<delete id="deleteByIds">
delete from emp where id in
<foreach collection="ids" item="id" separator="," open="(" close=")">
#{id}
</foreach>
</delete>
</mapper>