Mybatis学习笔记13 - 动态sql之set标签

示例代码：

接口定义：
package com.mybatis.dao;import com.mybatis.bean.Employee;public interface EmployeeMapper {public void updateEmp(Employee employee);public void updateEmployee(Employee employee);
}mapper定义：
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mybatis.dao.EmployeeMapper"><update id="updateEmp">update tbl_employee<set><if test="lastName!=null">last_name=#{lastName},</if><if test="email!=null">email=#{email},</if><if test="gender!=null">gender=#{gender}</if></set>where id=#{id}</update><update id="updateEmployee">update tbl_employee<trim prefix="set" suffixOverrides=","><if test="lastName!=null">last_name=#{lastName},</if><if test="email!=null">email=#{email},</if><if test="gender!=null">gender=#{gender}</if></trim>where id=#{id}</update>
</mapper>测试代码：
package com.mybatis.demo;import com.mybatis.bean.Employee;
import com.mybatis.dao.EmployeeMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;import java.io.IOException;
import java.io.InputStream;
import java.util.List;public class MyTest {public SqlSessionFactory getSqlSessionFactory() throws IOException {String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);return new SqlSessionFactoryBuilder().build(inputStream);}@Testpublic void test() throws IOException {SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();SqlSession openSession = sqlSessionFactory.openSession(true);try {EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);mapper.updateEmp(new Employee(1, "good", null, null));mapper.updateEmployee(new Employee(5, "test", null, null));} finally {openSession.close();}}
}