How to insert a new record with LinqToSql?

Googling shows there is to be an "Add" method for this, but there seems to 开发者_开发百科be no Add or anything alike in my LinqToSQL table classes. I've tried "Attach", but with no effect :-(

I use VS2010, .Net 4 and SQL Server 2008 R2.

My tables have no surrogate ID but a natural composite primary key.

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yourDatacontext.yourlinqClass.InsertOnSubmit(new yourlinqClass());

yourDatacontext.SubmitChanges();

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It's InsertOnSubmit() for LinqToSQL:

ctx.MyClass.InsertOnSubmit(newinstance);