1. 批量增加

<insert id="batchSaveUser">
        insert into t_user (user_name,sex) values
        <!-- 动态SQL之foreach的用法 -->
        <!-- collection="users" 用于指定循环集合的名称，如果接口中并未指定参数别名，那么默认就是list
         item="u" 用于指定每次循环后的对象的别名
         separator="," 用于指定每次循环后之间的分割符-->
        <foreach collection="users" item="u" separator=",">
            (#{u.userName},#{u.sex})
        </foreach>
    </insert>

1. 批量删除

<delete id="batchDeleteUser">
        delete from t_user where id in (
        <foreach collection="ids" item="id" separator=",">
            #{id}
        </foreach>
        )  

 </delete>

3-1. 第二种批量删除的写法
3-2. open表示该语句以什么开始，close表示以什么结束

<delete id="batchDeleteUser">
        delete from t_user where id in 
        <foreach collection="ids" item="id" separator="," open="(" close=")">
            #{id}
        </foreach>

</delete>

1. 复杂条件批量删除

	<delete id="deleteByLogic"  parameterType = "java.util.List">
     delete from user where id > 2000
         or id in
      <foreach collection="list"  item="item" open="(" separator="," close=")"  >
           #{item}
      </foreach>
</delete>

1. 复杂条件批量删除 建议增加联合索引

	<!--通过条件删除数据-->
    <delete id="batchDeleteByCondition">
        delete from test where
        <foreach collection="list" item="item" separator=" or " index="index">
            (name = #{item.name} and area_code = #{item.areaCode} and type = #{item.type})
        </foreach>
    </delete>

2. 复杂条件批量删除 IN操作

<delete id="deleteBatch" parameterType="java.util.List">
    delete from test
    where (PRSNLID, ENTID) in
    <foreach item="item" index="index" collection="list" separator="," open="(" close=")">
(#{item.prsnlid},#{item.entid})
	</foreach>
</delete>