Once we've modeled our database using the LINQ to SQL designer,
we can then easily write code to work against it. Below are a few code
examples that show off common data tasks:
1) Query Products From the Database
The code below uses LINQ query syntax to retrieve an
IEnumerable sequence of Product objects. Note how the code is querying
across the Product/Category relationship to only retrieve those products in the
"Beverages" category:
Figure 3
C#:
Figure 4
VB:
2) Update a Product in the Database
The code below demonstrates how to retrieve a single product
from the database, update its price, and then save the changes back to the
database:
Figure 5
C#:
Figure 6
VB:
Note: VB in "Orcas" Beta1 doesn't support Lambdas
yet. It will, though, in Beta2 - at which point the above query can be
rewritten to be more concise.
3) Insert a New Category and Two New Products into the
Database
The code below demonstrates how to create a new category,
and then create two new products and associate them with the category.
All three are then saved into the database.
Note below how I don't need to manually manage the primary
key/foreign key relationships. Instead, just by adding the Product
objects into the category's "Products" collection, and then by
adding the Category object into the DataContext's "Categories"
collection, LINQ to SQL will know to automatically persist the appropriate
PK/FK relationships for me.
Figure 7
C#
Figure 8
VB:
4) Delete Products from the Database
The code below demonstrates how to delete all Toy products
from the database:
Figure 9
C#:
Figure 10
VB:
5) Call a Stored Procedure
The code below demonstrates how to retrieve Product entities
not using LINQ query syntax, but rather by calling the
"GetProductsByCategory" stored procedure we added to our data model
above. Note that once I retrieve the Product results, I can update/delete
them and then call db.SubmitChanges() to persist the modifications back to the
database.
Figure 11
C#:
Figure 12
VB:
6) Retrieve Products with Server Side Paging
The code below demonstrates how to implement efficient
server-side database paging as part of a LINQ query. By using the Skip()
and Take() operators below, we'll only return 10 rows from the database -
starting with row 200.
Figure 13
C#:
Figure 14
VB:
