我正在寻找一些防止SQL注入的技巧。在一个论坛上告诉我我的代码不安全，我正在寻找一个足够好的人来帮助我解决此问题。

我有一个Web表单，提交后转到aspx.cs页，然后将数据插入ms sql数据库。

protected void Submit_Click(object sender, EventArgs e)
    {
        string FullStartTime = StartTimeHourList.SelectedValue + ":" + StartTimeMinuteList.SelectedValue + " " + StartTimeAMList.SelectedValue;
        string FullEndTime = EndTimeHourList.SelectedValue + ":" + EndTimeMinuteList.SelectedValue + " " + EndTimeAMList.SelectedValue;

        OleDbConnection conn;
        OleDbCommand cmd;
        conn = new System.Data.OleDb.OleDbConnection("");
        cmd = new System.Data.OleDb.OleDbCommand();
        conn.Open();
        cmd.Connection = conn;
        var sql = String.Format(@"INSERT INTO FormTable1 (Nonprofit, Contact, Phone, Email, Event, StartDate, EndDate, StartTime, EndTime, Place, Comments, SubmitDate) values 
                                                            ('{0}','{1}','{2}','{3}','{4}','{5}','{6}','{7}','{8}','{9}','{10}','{11}')",
                                                           NonprofitTxtBox.Text, ContactTxtBox.Text, PhoneTxtBox.Text, EmailTxtBox.Text, EventTxtBox.Text,
                                                           StartDateTxtBox.Text, EndDateTxtBox.Text, FullStartTime, FullEndTime, PlaceTxtBox.Text, CommentsTxtBox.Text, DateTime.Now);
        cmd.CommandText = sql;
        cmd.ExecuteNonQuery();
        conn.Close();
 }