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





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.");
        }
    }










32.36.DataTable
32.36.1.Loop through DataTable by DataRow
32.36.2.Use DataTable to insert a Row
32.36.3.Add Row to DataTable
32.36.4.Accessing Data Values in a DataTable or DataSet
32.36.5.Adding Columns to DataTable
32.36.6.Adding Constraint to DataTable
32.36.7.Adding a Calculated Column to a DataTable
32.36.8.Adding a Column to a Child DataTable That Displays Data from the Parent Table
32.36.9.Adding a Column to a Parent DataTable That Aggregates a Child Table's Column Values
32.36.10.Creating a DataColumn and Adding It to a DataTable
32.36.11.Creating a DataTable and Adding It to a DataSet
32.36.12.Retrieving a Result Set Using a DataTable or a DataSet
32.36.13.Pop DataTable
32.36.14.Output Constraint Properties
32.36.15.Output the rows from the DataTable with foreach loop over DataRowCollection
32.36.16.Modify DataTable
32.36.17.Loop through the rows in DataTable
32.36.18.Creating Single- and Multi-Column Primary Keys
32.36.19.Creating a Unique Constraint
32.36.20.Append columns to DataTable
32.36.21.Accessing FirstName value in row 3 directly
32.36.22.Filter Sort
32.36.23.Retrieves a schema table for a query