update .dbml file

Question

How to update .dbml file after making some changes in the database.

Answer 1

There's no built-in way to sync the dbml file/datacontext with the database after making changes (besides regenerating the entire dbml file by removing all or a selection of the entities and re-dragging them, or by using sqlmetal as suggested by other replies), but there are third-party tools that add refresh functionality to the Visual Studio L2S designer.

One such tool is my add-in, Huagati DBML/EDMX Tools. You can download it from http://www.huagati.com/dbmltools/ and get a trial license if you want to take it for a test spin.

Jim Wooley has a summary various Linq and Linq-to-SQL tools here:
http://www.thinqlinq.com/default/LINQ-Tools.aspx

...and Damien Guard has a list of tools/resources for L2S here:
http://damieng.com/blog/2009/06/04/linq-to-sql-resources