Tuesday, 25 November 2014

Ordering data in LINQ queries by more than one column

In this post I am going to show how to do ordering when you require to order data by using multiple columns.
In this post, I am going to show how to do ordering when you require to order data by using multiple columns.
By using .Orderby(x=>x.Columnname) in a LINQ query, we can easily order data in a source collection. Most new developers make use of the same function twice.Orderby(x=>x.Columnname).Orderby(x=>x.Columnname) and thinks that will do the ordering in multiple columns.

IEnumerable<Employee> emp = dc.Employees
                                 .OrderBy(x => x.Name)
                                 .OrderBy(x => x.Desc);

But it always does the order by the column you specified in the last OrderBy() method.
Following are two solutions 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 OrderBy() and ThenBy() together.
IEnumerable<Employee> emp = dc.Employees
                                  .OrderByx => x.Name)
                                 .ThenBy((x => x.Desc);

Solution 2

If you don't want to go for Lambda expression, you can easily achieve multiple ordering:
var emp = from e in dc.Employees
          orderby e.Name, e.Desc
          select e;

As you can see, in the above statement, after order by, you can add multiple columns and do the ordering on the multiple columns.

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