Dynamic Sorting in MS SQL Server

What Is Sorting?

Sorting is a process of arranging items in a sequence by some standard or principle.

In MS SQL, the ORDER BY clause is used to arrange the data in ascending or descending order.

How Dynamic Sorting Works in MS SQL

Let's think of a web application that displays employee information in a grid with FirstName, LastName, Email, Title, Phone, and few other columns. On clicking the column heading the result set should sort accordingly.

Here, the sort column is dynamic, it depends on the user who clicks. To implement the sort on all the columns we use the CASE statement in the ORDER BY clause.

In the query below, @SortColumn defines the column that needs to be sorted, and @SortType defines ascending or descending. And the columns required for dynamic sorting are included in the CASEs under ORDER BY.

DECLARE @SortColumn AS VARCHAR(100) = 'firstname'
       ,@SortType   AS VARCHAR(100) = 'asc'

SELECT EmployeeKey,FirstName,LastName,Title,EmailAddress
FROM dbo.DimEmployee WITH(NOLOCK)
ORDER BY 
CASE WHEN @SortColumn = 'FirstName'      AND @SortType ='ASC'  THEN FirstName    END ASC,
CASE WHEN @SortColumn = 'FirstName'      AND @SortType ='DESC' THEN FirstName    END DESC,
CASE WHEN @SortColumn = 'LastName'       AND @SortType ='ASC'  THEN LastName     END ASC,
CASE WHEN @SortColumn = 'LastName'       AND @SortType ='DESC' THEN LastName     END DESC,
CASE WHEN @SortColumn = 'Title'          AND @SortType ='ASC'  THEN Title        END ASC,
CASE WHEN @SortColumn = 'Title'          AND @SortType ='DESC' THEN Title        END DESC,
CASE WHEN @SortColumn = 'EmailAddress'   AND @SortType ='ASC'  THEN EmailAddress END ASC,
CASE WHEN @SortColumn = 'EmailAddress'   AND @SortType ='DESC' THEN EmailAddress END DESC

In a real-time application, this logic can be written in the stored procedure which is called on clicking on the column which needs to be sorted, the respective column name, and the sort order to be passed as parameters to the stored procedure.