顯示值

Question

我試圖加載值從SQL查詢標記：下面的代碼

sc.Open(); 
string type = Vehicle_cost.SelectedText; 
string query = ("select Type from Vehicle_Registor where Reg_No = '" + type + "';"); 

SqlCommand cmd1 = new SqlCommand(query, sc); 
SqlDataReader sdr = cmd1.ExecuteReader(); 
label23.Text = sdr.ToString(); 
sc.Close(); 

Answer 1

嘗試..

sc.Open(); 

string query = @"select Type from Vehicle_Registor where Reg_No = @Reg_No"; 

SqlCommand cmd1 = new SqlCommand(query, sc); 
cmd1.Parameters.AddWithValue("@Reg_No", Vehicle_cost.SelectedText); 

SqlDataReader sdr = cmd1.ExecuteReader(); 
sdr.Read(); 

label23.Text = sdr[0].ToString(); 

sc.Close(); 

Answer 2

嘗試是這樣的：

SqlCommand cmd1 = new SqlCommand(query, sc); 
using (SqlDataReader sdr = cmd1.ExecuteReader()) 
{ 
    while (sdr.Read()) 
    { 
     for (int i = 0; i < sdr.FieldCount; i++) 
     { 
      label23.text += sdr[i].ToString(); 
     } 
    } 
} 
sc.Close();