c＃wpf新数据覆盖以前的数据

Question

我正在使用一个小应用程序，用户可以从SQL中检索特定数据，用数据填充数据网格。用户可以从SQL数据库中检索数据，然后在文本框中写入条形码，然后搜索他搜索的数据。

到现在为止我使用了这段代码

            if (e.Key == Key.Enter)
            {
                SqlConnection con = new SqlConnection("Server = localhost;Database = Bilanc; Integrated Security = true");
                SqlCommand cmd = new SqlCommand("product", con); // Using a Store Procedure.
                cmd.CommandType = CommandType.StoredProcedure;
                DataTable dt = new DataTable("dtList");
                cmd.Parameters.AddWithValue("@Barcod", txtcode.Text);




                DataTable dataTable = new DataTable();//Created a new DataTable

                DataColumn dc = new DataColumn();//Made a new DataColumn to populate above DataTable
                dc.DataType = System.Type.GetType("System.String");//Defined the DataType inside, this can be [[int]] if you want.
                dc.ColumnName = "@Barcod";//Gave it a name (important for the custom expression - can only be one word so use underscores if you need multiple words)

                DataColumn dc2 = new DataColumn();
                dc2.DataType = System.Type.GetType("System.String");
                dc2.ColumnName = "@Product";

                DataColumn dc3 = new DataColumn();
                dc3.DataType = System.Type.GetType("System.Decimal");
                dc3.ColumnName = "@QTY";

                DataColumn dc4 = new DataColumn();
                dc4.DataType = System.Type.GetType("System.Decimal");
                dc4.ColumnName = "@Price";

                DataColumn dc5 = new DataColumn();
                dc5.DataType = System.Type.GetType("System.String");
                dc5.ColumnName = "@Tax";

                DataColumn dc6 = new DataColumn();
                dc6.DataType = System.Type.GetType("System.String");
                dc6.ColumnName = "Total";
                dc6.Expression = "@Price * @QTY";//Multiplying the Price and Quantity DataColumns

                dataTable.Columns.Add(dc);//Add them to the DataTable
                dataTable.Columns.Add(dc2);
                dataTable.Columns.Add(dc3);
                dataTable.Columns.Add(dc4);
                dataTable.Columns.Add(dc5);
                dataTable.Columns.Add(dc6);

                dtg.ItemsSource = dataTable.DefaultView;//Set the DataGrid ItemSource to this new generated DataTable

                con.Open();//Open the SQL connection

                SqlDataReader reader = cmd.ExecuteReader();//Create a SqlDataReader

                while (reader.Read())//For each row that the SQL query returns do
                {
                    DataRow dr = dataTable.NewRow();//Create new DataRow to populate the DataTable (which is currently binded to the DataGrid)
                    dr[0] = reader[0];//Fill DataTable column 0 current row (Product) with reader[0] (Product from sql)
                    dr[1] = reader[1];
                    dr[2] = reader[2];
                    dr[3] = reader[3];
                    dr[4] = reader[4];


                    dataTable.Rows.Add(dr);//Add the new created DataRow to the DataTable
                }
     }
    }

代码工作正常，但是当我遇到困难时，当我从SQL检索数据时，新数据会覆盖以前的数据。 我的问题是如何保留以前的数据 谢谢大家

Answer 1

尝试使用InsertAt（）方法代替具有适当位置参数的数据表的Add（）。