Razor web page db connection open and close

Have a look at my AddProducts.cshtml page and you will understand.

@{
Layout = "~/_Admin/_SiteLayout.cshtml";
Page.Title = "Προσθήκη Προιόντων";
var db = Database.Open("rentit");


WebImage photo = null;
var newFileName = "";
var imagePath = "";


if (IsPost)
{
//Getting TextBox value in string
string ProdName = Request.Form["prodname"];
string Cost = Request.Form["cost"];
string Description = Request.Form["desc"];
string Details = Request.Form["details"];
string Class = Request.Form["class"];
string Fuel = Request.Form["fuel"];
string Doors = Request.Form["doors"];
string GearBox = Request.Form["gearbox"];



photo = WebImage.GetImageFromRequest();
if (photo != null)
{
newFileName ="_" +
Path.GetFileName(photo.FileName);
imagePath = @"/images\" + newFileName;

photo.Save(@"~\" + imagePath);
}



var sqlinsert = "INSERT INTO Products (ProdName,Cost,Description,Details,Class,Fuel,Doors,GearBox,ImagePath) Values(@0,@1,@2,@3,@4,@5,@6,@7,@8)";
db.Execute(sqlinsert, ProdName.toGreeklish(), Cost, Description, Details, Class, Fuel, Doors, GearBox, newFileName);

Response.Redirect("/_Admin/Products.cshtml");
}

}

And in every page that i need to RUID something in my database i am using the Database.Open(); in every file

Well i just finished my internship so i decided to start learning ASP.NET MVC but because i am a total beginner even in c# i thought i would do something like this just as a test project and then slowly build in it the classes that i need just for education purposes.
But i dont know how to close the db connection and there is almost zero information about razor pages online.
So what do you suggest?