我的变量名称和数据库表都是正确的,但我收到了以下错误信息:
MySql.Data.MySqlClient.MySqlException: '已经有一个与此连接关联的打开的DataReader,必须先关闭它。'
public string urun_adi_bul(string urun_id)// find product name
{
if (genel.baglanti.State == ConnectionState.Closed)
{
genel.baglanti.Open();
}
string urun_adi = "";
genel.sqlgonder.Connection = genel.baglanti;
genel.sqlgonder.CommandText = "Select * from urunler where urun_id="+urun_id;
MySqlDataReader oku = genel.sqlgonder.ExecuteReader();
while (oku.Read())
{
urun_adi = oku["urun_id"].ToString();
}
oku.Close();
return urun_adi;// product name
}
public void hesapGetir(ListView lvSiparis, string masa_id)
{
genel.baglanti.Open();
MySqlCommand sqlgonder = new MySqlCommand();
sqlgonder.Connection = genel.baglanti;
sqlgonder.CommandText = "Select * from adisyonlar where masa_id = "+masa_id;
MySqlDataReader oku = sqlgonder.ExecuteReader();
lvSiparis.Items.Clear();
string urun_adi = "",urun_id="";
while (oku.Read())
{
urun_id = oku["urun_id"].ToString();
decimal fiyat = Convert.ToDecimal(urun_fiyati_bul(urun_id)); // price
decimal adet = Convert.ToDecimal(oku["urun_adet"]); // piece
decimal toplam = fiyat * adet; // total
urun_adi = urun_adi_bul(urun_id);
ListViewItem item = new ListViewItem(urun_adi);
item.SubItems.Add(adet.ToString());
item.SubItems.Add(toplam.ToString());
lvSiparis.Items.Add(item);
}
oku.Close();
genel.baglanti.Close();
}
如何在循环中使用两个数据读取器?
urun_fiyati_bul
函数的代码。你应该将数据连接起来,进行单个查询以检索所需的所有数据,可以参考 René 的答案中如何连接的示例。 - Cleptus