MyBatis--特殊SQL的执行
在上一个项目进行测试，项目初始化参考：开始准备工作
1、准备工作
创建mapper接口，路径在src/main/java/com/mybatis/mapper/SQLMapper.java
package com.mybatis.mapper;
public interface SQLMapper {
// 接口
}
创建mapper映射，路径在src/main/resources/com/mybatis/mapper/SQLMapper.xml
DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mybatis.mapper.SQLMapper">
mapper>
创建测试类，路径在src/test/java/com/mybatis/test/SQLMapperTest.java
package com.mybatis.test;
public class SQLMapperTest {
// 待测试方法
}
2、模糊查询
a>在SQLMapper接口添加方法
/**
* 根据用户名模糊查询用户信息
*/
List<User> getUserByLike(@Param("username") String username);
b>在SQLMapper映射添加查询
<select id="getUserByLike" resultType="User">
SELECT * FROM t_user WHERE username LIKE concat('%', #{username}, '%')
select>
第二种方式，使用${}，如下：
<select id="getUserByLike" resultType="User"> SELECT * FROM t_user WHERE username LIKE '%${username}%' select>第三种方式（推荐使用）：
<select id="getUserByLike" resultType="User"> SELECT * FROM t_user WHERE username LIKE "%"#{username}"%" select>
c>在SQLMapperTest添加测试方法
@Test
public void testGetUserByLike() {
SqlSession sqlSession = SqlSessionUtil.getSqlSession();
SQLMapper mapper = sqlSession.getMapper(SQLMapper.class);
System.out.println(mapper.getUserByLike("张"));
}
d>运行结果
[
User(id=1, username=张玉, password=123, age=23, sex=女, email=123@qq.com),
User(id=5, username=张飞, password=777, age=26, sex=男, email=ttt@gmail.com)
]
3、批量删除
a>在SQLMapper接口添加方法
/**
* 批量删除用户
*/
int deleteUserByIds(@Param("ids") String ids);
b>在SQLMapper映射添加删除
<delete id="deleteUserByIds">
DELETE FROM t_user WHERE id IN (${ids})
delete>
此时不能使用#{}
c>在SQLMapperTest添加测试方法
@Test
public void testDeleteUserByIds() {
SqlSession sqlSession = SqlSessionUtil.getSqlSession();
SQLMapper mapper = sqlSession.getMapper(SQLMapper.class);
System.out.println(mapper.deleteUserByIds("5,6,7"));
}
d>运行结果
4、动态设置表名
a>在SQLMapper接口添加方法
/**
* 动态设置表名，查询所有的用户信息
*/
List<User> getUserByTableName(@Param("tableName") String tableName);
b>在SQLMapper映射添加查询
<select id="getUserByTableName" resultType="User">
select * from ${tableName}
select>
由于表名不能加单引号，故此处只能用${}，而不能用#{}
c>在SQLMapperTest添加测试方法
@Test
public void testGetUserByTableName() {
SqlSession sqlSession = SqlSessionUtil.getSqlSession();
SQLMapper mapper = sqlSession.getMapper(SQLMapper.class);
System.out.println(mapper.getUserByTableName("t_user"));
}
d>运行结果
[
User(id=1, username=张玉, password=123, age=23, sex=女, email=123@qq.com),
User(id=2, username=雷利, password=577, age=25, sex=男, email=666@qq.com),
User(id=3, username=柳丰, password=999, age=24, sex=男, email=999@qq.com),
User(id=4, username=高敏, password=333, age=22, sex=女, email=111@163.com)
]
5、添加功能获取自增的主键
a>在SQLMapper接口添加方法
/**
* 添加用户信息
*/
int insertUser(User user);
b>在SQLMapper映射添加插入
<insert id="insertUser" useGeneratedKeys="true" keyProperty="id">
INSERT INTO t_user VALUES(#{id},#{username},#{password},#{age},#{sex},#{email})
insert>
useGeneratedKeys：设置使用自增的主键
keyProperty：因为增删改有统一的返回值是受影响的行数，因此只能将获取的自增的主键放在传输的参数user对象的某个属性中，此处放在id中
c>在SQLMapperTest添加测试方法
@Test
public void testInsertUser() {
SqlSession sqlSession = SqlSessionUtil.getSqlSession();
SQLMapper mapper = sqlSession.getMapper(SQLMapper.class);
User user = new User(null,"许嵩","666",30,"男","[email protected]"); // id在数据库中自增
System.out.println(mapper.insertUser(user));
System.out.println(user); // 此时User对象的id属性有值
}
d>运行结果
数据库
