Creating a Unique Constraint : DataTable « ADO.Net « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. ADO.Net
3. DataTable

using System;
using System.Data;

    class Program
    {
        static void Main(string[] args)
        {
            DataTable dt = new DataTable("Table-1");
            dt.Columns.Add("Id", typeof(int));
            dt.Columns.Add("Field1", typeof(string)).MaxLength = 50;
            UniqueConstraint uc1 = new UniqueConstraint("UniqueConstraint", dt.Columns["Field1"]);
            dt.Constraints.Add(uc1);

            try
            {
                AddRow(dt, 1, "Value 1");
                AddRow(dt, 2, "Value 1");
                AddRow(dt, 3, "Value 1");
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error: {0}", ex.Message);
            }
        }
        private static void AddRow(DataTable dt, int id, string field1)
        {
            Console.WriteLine("\nAdding row: {0}, {1}", id, field1);
            dt.Rows.Add(new object[] { id, field1 });
            Console.WriteLine("Row added.");
        }
    }