sql server将PK类型从int更改为uniqueidentifier

I need to change the type of my primary key column on a table from int to guid. The database already has data that I don't want to lose, and there are foreign keys to consider. Is there a painless way to do this or do I have to manually do it through a big a** script?:) I would appreciate any suggestionsI need to change the type of my primary key col