一张表，两个字段，里面有一部分数据完全重复，怎么删除重复数据？

delete from (select * from (select name,birthday,row_number() over(partition by name,birthday order by name,birthday) as row_num from user) as e where row_num >1)

执行上面一句话报错：
ERROR [57016] IBM SQL0668N Operation not allowed for reason code "7" on table "JZFY.USER".