# LINQ Support

Starting from the PPJ Framework 2009 release we have added full native Language Integrated Query (LINQ) support to the *SalArray* type and both the *SalTableWindow* control and *SalFormTableWindow* form.

LINQ adds extremely powerful language features for querying and extracting data from data collections. With built-in LINQ support in the PPJ Framework migrated code automatically supports LINQ constructs on existing objects.

## Arrays

All dynamic array declarations based on *SalArray<>* support LINQ. Using LINQ on *SalArray* instances is as easy as using LINQ on any .NET collection:

```csharp
SalArray<CCustomer> arCustomers = new SalArray<CCustomer();
...Populate array...
var ActiveCustomers = from c in arCustomers where c.Active = true
select c;
```

The code snippet above creates a collection *ActiveCustomers* populated by instances of *CCustomer* where the value of the member variable *Active* is equal to true.

## TableWindow Controls

LINQ support in table windows is different from *SalArray*. *SalTableWindows* contain dynamic columns and multiple rows and the final content and structure of of a table window is not fully determined until runtime.

The LINQ implementation of the *IEnumerable* interface in *SalTableWindow* returns the rows contained in the table window as instances of *SalTableRow*. Cell values in the row instance can be accessed using the name or the reference of the column. The same example listed for the *SalArray* LINQ implementation would look like the following code for a table window control:

```csharp
var ActiveCustomers = from r in tblCustomers 
    where r["colActive"].Number = "Y";

// or

var ActiveCustomers = from r in tblCustomers 
    where r[tblCustomers.colActive].Number = 1;
```

Using the column reference instead of the column name has the advantage to prevent broken references when the name of columns is changed since the compiler will enforce the symbol reference. However, using the column name as a string allows for more dynamic queries.

## Resources

If you want to try out a bit of LINQ, you can take a look at LINQPad: [http://www.linqpad.net](http://www.linqpad.net/)

For many useful LINQ samples you can use this page: <http://msdn.microsoft.com/en-us/vcsharp/aa336746.aspx>