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 :