mybatis用法

//引用其它mapper.xml的sql片段
<include refid="namespace.sql片段"/>

<sql>用来封装SQL语句, <include>来调用，如果用了refid="base_column_list"则：

</select>
    <select id="selectOne" resultMap="BaseResultMap">
        select
        <include refid="base_col_list"/>
        from entity_meta
        where id = #{entityId}
    </select>
   
      <sql id="base_col_list">
        id,
        zh_name,
        en_name,
        color,
        parent_entity_id,
        is_sys_source,
        recent_backup_time,
        is_backup
    </sql>

sql片段

       Sql中可将重复的sql提取出来，使用时用include引用即可，最终达到sql重用的目的，如下：

//建立sql片段
<sql id="query_user_where">
	<if test="id!=null and id!=''">
		and id=#{id}
	</if>
	<if test="username!=null and username!=''">
		and username like '%${username}%'
	</if>
</sql>

//使用include引用sql片段
<select id="findUserList" parameterType="user" resultType="user">
	select * from user
		<where>
			<include refid="query_user_where"/>
		</where>
</select>

//引用其它mapper.xml的sql片段
<include refid="namespace.sql片段"/>

https://www.cnblogs.com/sh086/p/8375791.html