使用<sql id="">,<include refid="">作用:方便一些sql内容,在多个地方重复使用;且使主sql语句比较简洁。
<sql id="baseColumnList" >
USERID, USERNAME, GENDER, AGE
</sql>
<select id="getUserById" parameterType="string" resultType="User">
SELECT
<
include refid="baseColumnList"
/>
FROM TEST_USER
WHERE USERID = #{userId}
</select>