演示UniqueConstraint类的使用

 （摘录自《C#函数实用手册》冶金工业出版社）

代码：

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            DataTable testDT = new DataTable("student");
            DataColumn testDC = new DataColumn("Id", Type.GetType("System.Int32"));
            testDT.Columns.Add(testDC);
            testDC = new DataColumn("Name",Type.GetType("System.String"));
            testDT.Columns.Add(testDC);
            testDC = new DataColumn("School",Type.GetType("System.String"));
            testDT.Columns.Add(testDC);

            DataColumn[] testDCA = new DataColumn[2];
            testDCA[0] = testDT.Columns["Id"];
            testDCA[1] = testDT.Columns["Name"];
           
            UniqueConstraint testUC = new UniqueConstraint("IdNameConstraint",testDCA);
            testDT.Constraints.Add(testUC);
           
            foreach(UniqueConstraint uc in testDT.Constraints)
            {
                // 使用Equals方法判断当前的UniqueConstraint对象是否与指定对象相同
                if (testUC.Equals(uc))
                {
                    Console.WriteLine("识别到主键约束:" + testUC.ConstraintName);
                    Console.WriteLine("该约束的哈希代码:" + testUC.GetHashCode());
                }
            }
            Console.ReadLine();
        }
    }
}

*****************************************

结果：

识别到主键约束：IdNameConstraint
该约束的哈希代码：37121646