Question

mybatis表关联查询

<select id="selectByPrimaryKey" resultMap="ResultMapWithBLOBs" parameterType="java.lang.Integer" >
select
<include refid="Base_Column_List" />
,
<include refid="Blob_Column_List" />
,department.Department_Name
from specialty a JOIN department b
on a.Department_Id = b.Department_Id
WHERE b.Department_Id = a.Department_Id
AND a.Specialty_Id = #{specialtyId,jdbcType=INTEGER}
</select>
报错
Column 'Department_Id' in field list is ambiguous
？？？？？？？？？？？？

Answer 1

select B.name,B.age,A.name from B表 B left join A表 A on B.a_id = A.id