Updating a single row in linq

Question

I'm trying to update a single row of a table, specifically using a primary key value using linq.

 var mytab = new Customer();
 mytab.FirstName = mymodel.FirstName;
 mytab.LastName = mymodel.LastName;
 mytab.CustomerId = mymodel.CustomerId;

 db.AddToCustomer(mytab);
 db.SaveChanges()

This adds a new row with a new id. Stepping through the code reveals that mymodel is passing the correct values with a first or last name that I want to update.

The mymodel.CustomerId is the correct id of the record I want to update but SQL Profiler shows I'm not updating anything. Do I need to use .First ?

Answer 1

Your code creates new row. For updating you need first select your Customer by id from database and then update:

var mytab = db.Customers.First(g=>g.CustomerId == mymodel.CustomerId);
 mytab.FirstName = mymodel.FirstName;
 mytab.LastName = mymodel.LastName;
 db.SaveChanges();