一、 <sql><include>

<sql>用于提取 SQL 语句, <include>用于引用 SQL 语句

 1 <sql id="tb_user">
 2         id,user,passwd
 3 </sql>
 4 
 5 <select id="selIn" resultType="User" parameterType="list">
 6         select
 7             <include refid="tb_user"/>
 8          from tb_user where id in
 9         <foreach collection="list" open="(" separator=","  close=")" item="item">
10             #{item}
11         </foreach>
12 </select>