Hi ramitaherwahd...,
Refer below code.
C#
DateTime startDate = new DateTime(DateTime.Now.Year, 1, 1);
DateTime endDate = DateTime.Today;
double diff = endDate.Subtract(startDate).TotalDays;
VB.Net
Dim startDate As DateTime = New DateTime(DateTime.Now.Year, 1, 1)
Dim endDate As DateTime = DateTime.Today
Dim diff As Double = endDate.Subtract(startDate).TotalDays
SQL
SELECT DATEDIFF(DAY, DATEADD(YY, DATEDIFF(YY, 0, GETDATE()), 0), GETDATE()) AS Diff