mybatis动态sql更新语法

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1.StudentDo

package cn.itcast.app05;import java.util.LinkedHashMap;import java.util.List;import java.util.Map;import org.apache.ibatis.session.SqlSession;import cn.itcast.util.MybatisUtil;public class StudentDao {public void dynaUpdate(Integer id,String name,Double sal) throws Exception{SqlSession sqlSession=null;try{sqlSession=MybatisUtil.getSqlSession();Map<String,Object> map=new LinkedHashMap<String,Object>();map.put("pid", id);map.put("pname", name);map.put("psal",sal);sqlSession.update(Student.class.getName()+".dynaUpdate", map);sqlSession.commit();}catch(Exception e){e.printStackTrace();sqlSession.rollback();throw e;}finally{MybatisUtil.closeSqlSession();}}//测试public static void main(String[] args) throws Exception{StudentDao dao=new StudentDao();dao.dynaUpdate(1,null,9000D);}}

2.映射文件

<?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="cn.itcast.app05.Student">    <resultMap type="cn.itcast.app05.Student" id="studentMap">       <id property="id" column="id"></id>       <result property="name" column="name"/>       <result property="sal" column="sal"/>     </resultMap>       <update id="dynaUpdate" parameterType="map">      update students      <set>          <if test="pname!=null">             name=#{pname},          </if>          <if test="psal!=null">             sal=#{psal},          </if>            </set>      where id=#{pid};   </update></mapper>

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