C# must declare the scaler variable

  public void datagrid(string sorgu)
       {
           // datagrid yüklenme methodu 
           try
           {
               sql_baglan();
               datagrid1.Visible = true;   // burada datagrid 1 hedef bilgileri
               datagrid1.Rows.Clear();       // datagridview temizlemee

               sqlkomut.CommandText = sorgu;
               SqlDataReader r = sqlkomut.ExecuteReader();
              

               
               int sayac=0;
               while (r.Read())
               {
                 sayac++;
                   datagrid1.Rows.Add(sayac,r["ad"], r["telefonno"] );
                 
               }

               r.Close();
               sql_kapat();
           }
           catch (Exception ex)
           {

               MessageBox.Show(ex.Message.ToString(), "Data Grid Methodu", MessageBoxButtons.OK, MessageBoxIcon.Error);
           }
       }

  private void bu_ara_Click(object sender, EventArgs e)
       {
           if (baglantivar == true)
           {
                     datagrid("SELECT * FROM islem WHERE telefonno=@tele ");
                      sqlkomut.Parameters.Add("@tele", SqlDbType.VarChar).value=te_ara_telefonno.Text.ToString();
               
                     
           }
  }