Comment comparer la saisie de la base de données et la saisie de formulaire

Question

J'utilise C # 2010 Express et SQL Compact.J'ai une table à deux colonnes et un formulaire pour ajouter des données à enregistrer sur la table.Mais je ne veux pas sauver les mêmes entrées.

Par exemple;

Name     City
Sefa     Istanbul
Sefa     New york
Sefa     London
Ben      New York
......

est ok mais si l'utilisateur veut ajouter un autre

Name     City
Sefa     Istanbul

ou déjà disponible une autre entrée, le programme doit s'arrêter.

J'ai ajouter ce code à mon projet, mais la commande checkcmd.executenonquery () renvoie toujours '-1'

SqlCeConnection Baglanti = new SqlCeConnection(@"Data Source=|DataDirectory|\CeoDatabase.sdf;Password=CeoDB;Persist Security Info=True");
            Baglanti.Open();


            string checkcommand = "SELECT BarAdi, BarSehri FROM Barlar WHERE BarAdi = '"+ Txt_BarAdi.Text +"' AND BarSehri = '"+Txt_BarSehri.Text+"'";
            SqlCeCommand checkcmd = new SqlCeCommand(checkcommand, Baglanti);
            int kontrol = checkcmd.ExecuteNonQuery();
            MessageBox.Show(kontrol.ToString());
            return;
            if (checkcmd.ExecuteNonQuery() < 1)
            {
                MessageBox.Show("Bu bilgiler ile kayıtlı bir bar zaten mevcut");
                return;
            }
            else
            {
                SqlCeCommand Islem = new SqlCeCommand("INSERT INTO Barlar(BarAdi,BarSehri)VALUES('" + Txt_BarAdi.Text + "','" + Txt_BarSehri.Text + "')", Baglanti);
                Islem.ExecuteNonQuery();
                MessageBox.Show("İşlem başarıyla tamamlandı");
            }


            Baglanti.Close();

Answer 1

You can have it one of the ways

• Either set Unique Key for that column in Database . When new record will be inserted it will be automatically checked (Preferred)

• Or while Inserting new record check if that city already exist.

If you want to check for exist combination. Do somthing like this (I assume this how you have your data):

SqlCeConnection cn = new SqlCeConnection("your connection string");
string checkcommand = "SELECT [Name], [City] FROM [Tablename]" +
                      "WHERE [Name] == @name AND [City] == @city" ;
SqlCeCommand checkcmd= new SqlCeCommand(checkcommand, cn);
checkcmd.Parameters.AddWithValue("@name", txtBoxName.Text);
checkcmd.Parameters.AddWithValue("@city", txtBoxCity.Text);
cn.Open();
//Check if record already exist
if(checkcmd.ExecuteNonQuery() > 0)
{
    //It already exist
}
else
{
   //It doesn't exist Insert new record
}