mybatis多条件查询问题

xml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="">  
    <select id="selectTeacher" parameterType="map" resultType="map">  
        select t.tid,t.tname,t.taddr  
        from test_teacher t  
        where 1=1  
        <if test="tid != '' and tid != null">  
            and tid=#{tid}  
        </if>  
        <if test="tname != '' and tname != null">  
            and tname like #{tname}  
        </if>  
        <if test="addrs != '' and addrs != null">  
            and taddr in  
            <foreach item="item" index="index" collection="addrs" open="("  
                separator="," close=")">  
                #{item}  
            </foreach>  
        </if>  
        ;
    </select>  
  
  
</mapper>  

dao层：

package mybatis.dao;  
  
import java.util.List;  
  
public interface TestTeacherDao {  
    public List selectTeacher(String tid,String tname,List addrs);  
}  

<!--动态SQL语句，多条件查询-->
   <select id="findSomeByMore" resultType="userInfoModel" parameterType="hashmap">
      select * from userinfo
--        (where标签自动去掉满足条件的第一个and)
      <where>
         <if test="userName!=null">
            and username=#{userName}
         </if>
         <if test="gender != null">
            and gender=#{gender}
         </if>
         <if test="orderId != null">
            and id in (select userid from orders where id=#{orderId})
         </if>

      </where>

   </select>

批量删除
 <delete id="partDelete" parameterType="list" >
   delete from userinfo
   <where>
      <if test="list!=null and list.size()>0">
         <foreach collection="list" item="id" open="id in (" separator="," close=")">
            #{id}
         </foreach>
      </if>
   </where>
</delete>