<?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="com.sincere.smartSearch.mapper.UserMapper"> <select id="selectStudentNumByStudentId" parameterType="java.lang.Integer" resultType="java.lang.String"> select student_num from SZ_V_School_Student where student_id = #{studentId} </select> </mapper>