sample13.cs

C#函数手册

namespace apiBook
{
	using System;
	using System.Data;
	using System.IO;
	public class TestClass 
	{ 
		public static void Main()
		{
			TestClass test=new TestClass();
			DataSet testDS=new DataSet("Test");
			DataTable testDT = new DataTable("student");
			DataTable testDTA = new DataTable("course");
			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("CId",Type.GetType("System.Int32"));
			testDT.Columns.Add(testDC);
			testDC = new DataColumn("CName",Type.GetType("System.String"));
			testDTA.Columns.Add(testDC);
			testDC = new DataColumn ("CId",Type.GetType("System.Int32"));
			testDTA.Columns.Add(testDC);
			testDS.Tables.Add(testDTA);
			testDS.Tables.Add(testDT);
			DataColumn pDC = testDS.Tables ["student"].Columns["Id"];
			DataColumn cDC = testDS.Tables ["course"].Columns["CId"];
			ForeignKeyConstraint testFK =new ForeignKeyConstraint("IdConstraint", pDC, cDC);		testFK.DeleteRule = Rule.SetNull;
			//当值被删除时将值设为空
			testFK.UpdateRule = Rule.Cascade;
			testFK.AcceptRejectRule = AcceptRejectRule.Cascade;
			testDS.Tables["course"].Constraints.Add(testFK);
			testDS.EnforceConstraints = true;
			foreach(ForeignKeyConstraint fkc in testDS.Tables["course"].Constraints)
			{
				if(testFK.Equals(fkc))
					//使用Equals方法判断当前的ForeignKeyConstraint对象是否与指定对象相同
				{
					Console.WriteLine("识别到外键约束："+testFK.ConstraintName);
					Console.WriteLine("该约束的哈希代码："+testFK.GetHashCode());
					//使用GetHashCode方法获取
					//ForeignKeyConstraint对象的此实例的哈希代码
				}
			}
			Console.ReadLine();
		}	
	}
}