Sunday, June 12, 2011

Ordering data in LINQ Queries by more than one column

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In this post I am going to show how to do ordering when you require to order data by using the multiple columns.

By using .Orderby(x=>x.Columnname) in the LINQ query we can easily order data of the source collection. So most of new developer make use of the same function two time .Orderby(x=>x.Columnname).Orderby(x=>x.Columnname) and thinks that will do the ordering on the multiple columns.
IEnumerable<Employee> emp = dc.Employees
                                 .OrderBy(x => x.Name)
                                 .OrderBy(x => x.Desc); 

But its always does the order by the column you specified in the last OrderBy() method.

Following is two solution to achieve
Solution 1:
Always make use of ThenBy() after OrderBy() because  OrderBy() returns an IOrderedEnumerable which then exposes the Methods: ThenBy() and ThenByDescending(). This means that we can OrderBy on multiple Fields by chaining the OrderBy() and ThenBy() together.
IEnumerable<Employee> emp = dc.Employees
                                  .ThenBy(x =< x.Name)
                                  .OrderBy(x => x.Desc);

Solution 2:
If you don't want to go for the Lamda expression where you can easily achieve the multiple ordering
var emp = from e in dc.Employees
          orderby e.Name, e.Desc
          select e;
As you can see in above statement after order by you can add the multiple columns and do the ordering on multiple columns.

1 comment:

  1. Thanks, that worked like a charm :-)

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