LINQ to Entities returning “Object reference not set to an instance of an object.”

EF does not support nullable composite primary keys if your one of the keys is null it will return the exception

How to store string in a cookie and retrieve it

Writing a cookie

HttpCookie myCookie = new HttpCookie("MyTestCookie");
DateTime now = DateTime.Now;
 
// Set the cookie value.
myCookie.Value = now.ToString();
// Set the cookie expiration date.
myCookie.Expires = now.AddYears(50); // For a cookie to effectively never expire
 
// Add the cookie.
Response.Cookies.Add(myCookie);

Reading a cookie

HttpCookie myCookie = Request.Cookies["MyTestCookie"];
 
// Read the cookie information and display it.
if (myCookie != null)
    Response.Write("<p>" + myCookie.Name + "<p>" + myCookie.Value);
else
    Response.Write("not found");

why cookies are always null after postback

private static string GetCookie(string name)
{
    return HttpContext.Current.Request != null ? HttpContext.Current.Request.Cookies[name].Value : string.Empty;
}
 
private static void SetCookie(string name, string value)
{
    HttpContext.Current.Request.Cookies[name].Value = value;
    HttpContext.Current.Request.Cookies[name].Expires = DateTime.Now.AddDays(100);
}

How to check if column exists in SQL Server table

IF EXISTS(SELECT * FROM sys.columns 
WHERE Name = N'columnName' AND Object_ID = Object_ID(qualified.table.name')) 
BEGIN 
    PRINT 'Column Exists'
END
--OR
IF COL_LENGTH('qualified.table.name','column_name') IS NULL
BEGIN
    PRINT 'Column does not exist or caller does not have permission to view the object'
END