ADO.NET 3.5 Cookbook, 2nd Edition

5.9. Adding Records with a GUID Primary Key

Problem

You want to add records to a DataTable that uses a GUID as its primary key.

Solution

Use the DataTable.RowChanging event handler to generate new GUID values for each row.

The solution creates a DataTable that has a GUID primary key column Id with the DefaultValue set to a new GUID. An event handler is added for the RowChanging event of the DataTable. The RowChanging event handler sets the default value of the primary key column in the DataTable to a new GUID value when a new row is added.

The C# code in Program.cs in the project AddRecordGuidPrimaryKey is shown in Example 5-16.

Example 5-16. File: Program.cs for AddRecordGuidPrimaryKey solution

using System;
using System.Data;
using System.Data.SqlClient;

namespace AddRecordGuidPrimaryKey
{
    class Program
    {
        static void Main(string[] args)
        {
            // Build the data table
            DataTable dt = new DataTable(  );
            // The Id column is a GUID; set the default value to a new GUID dt.Columns.Add("Id", typeof(Guid)).DefaultValue = Guid.NewGuid( ); dt.Columns.Add("Field1", typeof(string)).MaxLength = 50; dt.Columns.Add("Field2", typeof(string)).MaxLength = 50; // event handler sets the default value of Id to a new GUID value dt.RowChanging += new DataRowChangeEventHandler(dt_RowChanging); // Add five rows to the table for (int i = 1; i <= 5; i++) { // Create the new row DataRow row = dt.NewRow( ); row.SetField<string>("Field1", "field 1." + i); row.SetField<string>("Field2", "field 2." + i); dt.Rows.Add(row); ...