import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.session.SqlSession;
import cn.itcast.javaee.mybatis.util.MybatisUtil;
/**
* 持久层
* @author AdminTC
*/
public class StudentDao {
/**
* 有条件更新学生
*/
public void dynaUpdate(Integer id,String name,Double sal) throws Exception{
SqlSession sqlSession = null;
try{
sqlSession = MybatisUtil.getSqlSession();
Map<String,Object> map = new HashMap<String, Object>();
map.put("pid",id);
map.put("pname",name);
map.put("psal",sal);
sqlSession.update("studentNamespace.dynaUpdate",map);
sqlSession.commit();
}catch(Exception e){
e.printStackTrace();
sqlSession.rollback();
throw e;
}finally{
MybatisUtil.closeSqlSession();
}
}
public static void main(String[] args) throws Exception{
StudentDao dao = new StudentDao();
//关注SQL的变化
//dao.dynaUpdate(1,null,9000D);//update students set sal=? where id=?
//dao.dynaUpdate(1,"笨笨",null);//update students set name=? where id=?
dao.dynaUpdate(1,"笨笨",10000D);//update students set name=? and sal=? where id=?
}
}
<?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="studentNamespace">
<resultMap type="cn.itcast.javaee.mybatis.app12.Student" id="studentMap">
<id property="id" column="students_id"/>
<result property="name" column="students_name"/>
<result property="sal" column="students_sal"/>
</resultMap>
<!-- set标签自动判断哪个是最后一个字段，会自动去掉最后一个,号 -->
<update id="dynaUpdate" parameterType="map">
update students
<set>
<if test="pname!=null">
students_name = #{pname},
</if>
<if test="psal!=null">
students_sal = #{psal},
</if>
</set>
where students_id = #{pid}
</update>
</mapper>
原文地址：http://blog.51cto.com/357712148/2107439
