code first database : SqlException: Violation of PRIMARY KEY constraint 'PK_dbo.PrivatKasses'. - sql

Question

I have a model like this:
class PrivatKasse
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int ID { get; set; }
public decimal Betrag { get; set; }
public int BenutzerID { get; set; }
}
and a function that checks if the table is empty. if yes functions adds new rows. The function:
public static void DatabaseChecker()
{
using (var _db = new DataContext())
{
if (!_db.KasseGemeinsam.Any())
{
_db.KasseGemeinsam.Add(new Models.Data.KasseGemeinsamModel() { Jahr = DateTime.Now.Year.ToString(), Monat = MonatenVertauchen.ZahlZuMonaten(Convert.ToInt32(DateTime.Now.Month)), Haushalt = 0, Hygine = 0, Mobel = 0, Nahrung = 0, Schreibware = 0, Sonstiges = 0 });
_db.SaveChanges();
}
if (!_db.KassePrivat.Any())
{
_db.KassePrivat.Add(new Models.Data.KassePrivatModel() { Jahr = DateTime.Now.Year.ToString(), Monat = MonatenVertauchen.ZahlZuMonaten(Convert.ToInt32(DateTime.Now.Month)), UserID = UserIdentity.UserID, Fahrkosten = 0, Hygine = 0, Mobel = 0, Nahrung = 0, Schreibware = 0, Sonstiges = 0 });
_db.SaveChanges();
}
if (!_db.GemeinsamKasse.Any())
{
_db.GemeinsamKasse.Add(new Models.Data.GemeinsamKasse() { Betrag = 0 });
_db.SaveChanges();
}
if (!_db.PrivatKasse.Any())
{
List<int> userIDs = new List<int>();
foreach (var item in _db.UsersTbl)
{
userIDs.Add(item.ID);
}
using (var _db2 = new DataContext())
{
foreach (var item in userIDs)
{
_db2.PrivatKasse.Add(new Models.Data.PrivatKasse() { BenutzerID = item, Betrag = 0 });
}
_db2.SaveChanges();
}
}
}
But I get an SqlExeption :
System.Data.Entity.Infrastructure.DbUpdateException: "An error occurred while updating the entries. See the inner exception for details."
UpdateException: An error occurred while updating the entries. See the
inner exception for details.
SqlException: Violation of PRIMARY KEY constraint
'PK_dbo.PrivatKasses'. Cannot insert duplicate key in object
'dbo.PrivatKasses'. The duplicate key value is (0).
The statement has been terminated.
How can i fix this problem?

Answer 1

I believe the issue is because you are not providing the id (and the default in a int is 0) since you declare
[DatabaseGenerated(DatabaseGeneratedOption.None)]
which means that the db will not create the id, I recommend to use Identity instead
[DatabaseGenerated(DatabaseGeneratedOption.Identity )]
then you should be able to use
_db2.PrivatKasse.Add(new Models.Data.PrivatKasse() { BenutzerID = item, Betrag = 0 })
otherwise provide the id
_db2.PrivatKasse.Add(new Models.Data.PrivatKasse() {ID= customID, BenutzerID = item, Betrag = 0 })