iHotel_student_houtai/src/main/resources/mapper/template/BuildingMapper.xml

<?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.template.mapper.BuildingMapper">

    <select id="group" resultType="java.lang.String">
        SELECT
            building
        FROM
            `building`
        where deleted=0
        GROUP BY building
    </select>
</mapper>