使用c#更新Id主键字段

Hai, like the title.. I just wanna make sure how if I want to update primary key in LINQ? I did google and found that it`s impossible to update Id in Linq. the other way is I delete the old record and insert new but the problem is it will be not effective if the table has a relationship with other table..maybe someone give me a better way to solve it.Hai, like the title.. I just wanna make sure ho