Previously I stated that I dislike the separation between the code and the
database schema. A first look at SqlMetal.exe, a utility that comes with DLinq
suggested that it might ease the problems and guess what, it does :-)
I created a small sample app and added the following command to the pre-build
event:
"c:\Program Files\LINQ Preview\Bin\SqlMetal.exe" /database:Northwind /code:"$(ProjectDir)Northwind.vb"
/language:vb
Build the project to have the Northwind.vb file generated and include it in
the project.
Next I added the following code:
Sub main()
Dim northwind
AsNew Northwind(My.Settings.DataConnection)
' Build a list cities
with multiple customers
Dim results =
From customer In
( _
From
customer In northwind.Customers _
GroupBy
customer.Country, customer.City _
Select
it.Key, it, Count(it)) _
Where
customer.Count > 1 _
Select
customer _
OrderBy
customer.Count Descending,
customer.Key.Country, customer.Key.City
ForEach row
In results
' Print the
country and city
Console.WriteLine("Country:
{0} - City: {1} - Count: {2}", _
row.Key.Country, row.Key.City,
row.Count)
' Print the
customers for the city
ForEach
customer In row.it
Console.WriteLine("
=> {0}", customer.CompanyName)
Next
Next
Console.ReadKey()
EndSub
Now build and run the project and you will see the output appear.
Now go open the table schema for the Customers table and change the City
column name to TheCity. Save the changes and try to run. This time you will
get compile errors on every reference to the City property because its no
longer valid.
Easy to do and so much better than runtime errors that the City column name
is invalid.
