当我在远程服务器上的表中有现有数据时，在我的表中添加外键？

I have existing data in my Student table. Now I want to add the foreign key in it. When I try to add the foreign key with existing data it gives error "The ALTER TABLE statement conflicted with the FOREIGN KEY constraint". If I delete all data from Student table then it adds foreign key successfully. Now I want to add foreign key without losing the data on remote server. How can I do it? I have seen various answers but did not find the solution. I have existing data in my Student table. Now I