anchor.diff:  
   ctx.SubmitUpdates()
   
  -(** update a single row 
  +(** update a single row
  +    assuming Id is unique
   *)
   
   type Employee2 = {
  
positive.code:         e.LastName <- employee.LastName
      )
      ctx.SubmitUpdates()
  
  
  (**Finally it is also possible to specify a seq of `string * obj` which is exactly the 
  
negative.code: }
  
  let updateEmployee (employee: Employee2) =
      let foundEmployee = query {
          for p in ctx.Public.Employee2 do
          where (p.Id = employee.Id)
          exactlyOneOrDefault
      }
      if not (isNull foundEmployee) then
          foundEmployee.FirstName <- employee.FirstName
          foundEmployee.LastName <- employee.LastName
      ctx.SubmitUpdates()
  
  let updateEmployee' (employee: Employee2) =
      query {
          for p in ctx.Public.Employee2 do
          where (p.Id = employee.Id)
  