動態SQL指：通過mtbatis提供的各種標籤實現動態拼接sql語句

<!--動態SQL語句，多條件查詢-->
<select id="findSomeByMore" resultType="userInfoModel" parameterType="hashmap">
      select * from userinfo
--        (where標籤自動去掉滿足條件的第一個and)
      <where>
         <if test="userName!=null">
            and username=#{userName}
         </
 
if>
         <if test="gender != null">
            and gender=#{gender}
         </if>
         <if test="orderId != null">
            and id in (select userid from orders where id=#{orderId})
         </if>

      </where>

   </select>

<delete id="partDelete" 
 
parameterType="list" >
   delete from userinfo
   <where>
      <if test="list!=null and list.size()>0">
         <foreach collection="list" item="id" open="id in (" separator="," close=")">
            #{id}
         </foreach>
      </if>
   </where>
</delete
 
>