Create Unique Constraint

UniqueConstraint Class represents a restriction on a set of columns in which all values must be unique.

Following example show how to create Unique Constraint

using System;

using System.Data;

namespace CreateUniqueConstraint

{

classProgram

{

staticvoid Main(string[] args)

{

// Create a table

DataTable objmyTable = newDataTable("MyTable");

// Add two columns

objmyTable.Columns.Add("Id", typeof(int));

objmyTable.Columns.Add("Name", typeof(string));

// Create a unique constraint on Field1

UniqueConstraint objUnique = newUniqueConstraint("UniqueConstraint", objmyTable.Columns["Id"]);

// Add the constraint to the table

objmyTable.Constraints.Add(objUnique);

// Verify the unique constraint by adding rows

try

{

objmyTable.Rows.Add( 1, "mukesh");

objmyTable.Rows.Add(2, "vinay");

objmyTable.Rows.Add(1, "ashish");

}

catch (Exception ex)

{

Console.WriteLine("\nError: {0}", ex.Message);

}

Console.WriteLine("\nPress any key to continue.");

Console.ReadLine();

}

Output :