我的配置信息:
server:
port: 8080
spring:
datasource:
username: root
password: 88888888
url: jdbc:mysql://localhost:3306/test_db?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
mapper-locations: classpath:mapping/*Mapping.xml
type-aliases-package: com.example.demo
1.简单的增删改查,这里用到的表是st5
(1)mapping的接口数据
@Repository
public interface UserMapper {
Stu Sel(int id);
List<Stu> selectAllStu();
void saveStu(Stu stu);
void delStu(int id);
void upadteStu(Stu stu);
}
mapping的配置
<?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.example.demo.service.UserMapper">
<select id="Sel" resultType="com.example.demo.domain.Stu">
select * from st5 where id = #{id}
</select>
<select id="selectAllStu" resultType="com.example.demo.domain.Stu">
select * from st5
</select>
<insert id="saveStu" parameterType="com.example.demo.domain.Stu" >
insert into st5 values (#{id},#{name},#{age})
</insert>
<delete id="delStu">
delete from st5 where id = #{id}
</delete>
<update id="upadteStu" parameterType="com.example.demo.domain.Stu">
UPDATE st5 SET name = #{name},age = #{age} WHERE id = #{id}
</update>
</mapper>
插入的时候返回id <insert id="add" parameterType="com.example.demo.domai.Stu">
<!--通过mybatis框架提供的selectKey标签获得自增产生的ID值-->
<selectKey resultType="java.lang.Integer" order="AFTER" keyProperty="id"> select LAST_INSERT_ID() </selectKey>
insert into st5 values (null,#{name},#{age})
</insert>
如果是多对多关系的话，就可以这查询
<collection property="emps"
ofType="com.example.demo.domain.Employee"
select="EmployeeMapping.findbyid"
column="id">
</collection>
<select id="findbyid" resultType="com.example.demo.domain.Employee">
select * from employee where dep_id = #{id}
</select>
2.多表查询的配置一对一
<?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.example.demo.service.EmployeeMapper">
<select id="selectAllEmployee" resultType="com.example.demo.domain.Employee">
select * from employee
</select>
<!--
<resultMap id="selectEmpAndDep" type="com.example.demo.domain.Employee">
<id property="id" column="eid" />
<result property="name" column="name" />
<result property="age" column="age" />
<result property="department.id" column="did" />
<result property="department.dep_name" column="dep_name" />
<result property="department.dep_location" column="dep_location" />
</resultMap>-->
<resultMap id="selectEmpAndDep" type="com.example.demo.domain.Employee">
<id property="id" column="eid" />
<result property="name" column="name" />
<result property="age" column="age" />
<association property="department" javaType="com.example.demo.domain.Department" >
<result property="id" column="did" />
<result property="dep_name" column="dep_name" />
<result property="dep_location" column="dep_location" />
</association>
</resultMap>
<select id="selectEmpAndDep" resultMap="selectEmpAndDep">
SELECT *,employee.id eid,department.id did FROM employee ,department WHERE employee.dep_id = department.id
</select>
</mapper>
对标查询一对多
<if test="value != null and value != '' and value.length > 0">
<?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.example.demo.service.UserMapper">
<select id="Sel" resultType="com.example.demo.domain.Stu">
select * from st5 where id = #{id}
</select>
<select id="selectAllStu" resultType="com.example.demo.domain.Stu">
select * from st5
</select>
<insert id="saveStu" parameterType="com.example.demo.domain.Stu" >
insert into st5 values (#{id},#{name},#{age})
</insert>
<delete id="delStu">
delete from st5 where id = #{id}
</delete>
<update id="upadteStu" parameterType="com.example.demo.domain.Stu">
UPDATE st5 SET name = #{name},age = #{age} WHERE id = #{id}
</update>
</mapper>
<!--根据ID动态修改检查组相关字段-->
<update id="updateStu" parameterType="com.example.demo.domain.Stu">
update st5
<set>
<if test="name != null">
name = #{name},
</if>
<if test="age != null">
sex = #{sex},
</if>
</set>
where id = #{id}
</update>
<resultMap id="selectDeApndEmp" type="com.example.demo.domain.Department">
<id property="id" column="did" />
<result property="dep_name" column="dep_name" />
<result property="dep_location" column="dep_location" />
<collection property="emps" ofType="com.example.demo.domain.Employee" >
<result property="id" column="eid" />
<result property="name" column="name" />
<result property="age" column="age" />
</collection>
</resultMap>
<select id="selectDepAndEmp" resultMap="selectDeApndEmp">
SELECT *,department.id did ,employee.id eid FROM department,employee WHERE department.id = employee.dep_id;
</select>
3.条件语句查询
<select id="findByCondition" parameterType="com.example.demo.domain.Stu" resultType="com.example.demo.domain.Stu">
select * from st5
<where>
<if test="id!=0">
and id=#{id}
</if>
<if test="name!=null">
and name=#{name}
</if>
<if test="age!=0">
and age=#{age}
</if>
</where>
</select>
if也可以这么写
<if test="age!=0 or age!=null">
<if test="age!=0 and age!=null">
foreach
<sql id="selectUser" select * from User</sql>
<select id="findByIds" parameterType="list" resultType="user">
select * from st5
<where>
<foreach collection="array" open="id in(" close=")" item="id" separator=",">
#{id}
</foreach>
</where>
</select>
int[] ids = new int[]{2,5};
List<User> userList = userMapper.findByIds(ids);
分页,导入坐标
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.3.0</version>
</dependency>
.yml文件配置
pagehelper: helperDialect: mysql reasonable: true supportMethodsArguments: true pageSizeZero: true params: count=countSql
使用:
PageHelper.startPage(2,2);
List<Stu> list = userService.getAllStu();;
PageInfo<Stu> pageInfo = new PageInfo<Stu>(list);
System.out.println("总条数："+pageInfo.getTotal());
System.out.println("总页数："+pageInfo.getPages());
System.out.println("当前页："+pageInfo.getPageNum());
System.out.println("每页显示长度："+pageInfo.getPageSize());
System.out.println("是否第一页："+pageInfo.isIsFirstPage());
System.out.println("是否最后一页："+pageInfo.isIsLastPage());
return list;