編輯在文本框中顯示的數據庫行的值

Question

對WPF不熟悉。我想編輯在文本框中顯示的數據庫行的值。此刻我收到一個錯誤：「ExecuteNonQuery：連接屬性尚未初始化」。當我刪除where子句時，所有的行都被更新，而不僅僅是所選的項目。

private void btnEDIT_Click(object sender, RoutedEventArgs e) 
{ 
    try 
    { 
     sc.Open(); 
     cmd = new SqlCommand("Update Rewards set Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'where Name = '" + this.txtName.Text +"'"); 
     cmd.ExecuteNonQuery(); 
     MessageBox.Show("Update Successfull"); 
     sc.Close(); 
    } 
    catch (Exception ex) 
    { 
     MessageBox.Show(ex.Message); 
    } 
} 

Answer 1

您沒有設置SqlCommand的Connection財產。所以命令不知道在哪裏連接。從SqlCommand使用constructor overload，或將其分開這樣

cmd.Connection = sc; 

Answer 2

cmd = new SqlCommand("Update Rewards set Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'where Name = '" + this.txtName.Text +"'",sc); // add connection here 

也應使用參數化查詢或存儲過程，以防止SQL注入攻擊。

SqlCommand cmd = new SqlCommand("Update Rewards set Name = @name, Cost= @cost where Name = @name ,sc); 
cmd.Parameters.AddWithValue("@name", Convert.ToString(this.txtName.Text)); and so on 

Answer 3

我希望這是你需要的:)複製粘貼這個。祝你好運，兄弟！ :)如果你有問題，只是問，我會回答，如果我知道哈哈:)

private void btnEDIT_Click(object sender, RoutedEventArgs e) 
{ 
    try 
    { 
     sc.Open(); 
     sql = "UPDATE REWARDS SET Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'WHERE Name = '" + this.txtName.Text +"'"); 
     SqlCommand command = new SqlCommand(sql, con); 
     command.ExecuteNonQuery(); 
     MessageBox.Show("Update Successfull"); 
     sc.Close(); 
    } 
    catch (Exception ex) 
    { 
     MessageBox.Show(ex.Message); 
    } 
}