mybatis動态sql查詢文法

1.StudentDao

package cn.itcast.app04;

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 {
	
	//有條件的查詢
	public List<Student> findAll(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);
			return sqlSession.selectList(Student.class.getName()+".findAll", map);
		}catch(Exception e){
			e.printStackTrace();
			throw e;
		}finally{
			MybatisUtil.closeSqlSession();
		}
	}
	
	
	
	//測試
	public static void main(String[] args) throws Exception{
		StudentDao dao=new StudentDao();
		List<Student> studentList=dao.findAll(null,null,null);
		for(Student s:studentList){
			System.out.println(s.getId()+":"+s.getName()+":"+s.getSal());
		}
	}
}
           

2.映射檔案

<?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.app04.Student">

    <resultMap type="cn.itcast.app04.Student" id="studentMap">
       <id property="id" column="id"></id>
       <result property="name" column="name"/>
       <result property="sal" column="sal"/> 
    </resultMap>
    
   <select id="findAll" parameterType="map" resultType="cn.itcast.app04.Student">
        select id,name,sal from students 
        <where>
          <if test="pid!=null">
              and id=#{pid}
          </if>
          <if test="pname!=null">
              and name=#{pname}
          </if>
          <if test="psal!=null">
              and sal=#{psal}
          </if>
        </where>
   </select>

</mapper>