一个包含3个DataTable对象的DataSet:

以下创建了一个包含3个DataTable对象的DataSet:

private void button1_Click(object sender, EventArgs e)
        ...{
            SqlConnection con = new SqlConnection();
            con.ConnectionString = (@"Data source=localhost;Integrated Security=true;database=Northwind");
            try
            ...{
                string SQL1 = "SELECT * FROM Orders";
                string SQL2 = "SELECT * FROM Employees";

                DataSet ds = new DataSet();
                DataTable tb1;
                DataColumn col;
                ForeignKeyConstraint fk;

                      //创建客户表
                tb1 = ds.Tables.Add("Customers");
                col=tb1.Columns.Add("CustomerID",typeof(string));
                col.MaxLength=5;
                col=tb1.Columns.Add("CompanyName",typeof(string));
                col.MaxLength=40;
                col=tb1.Columns.Add("ContactName",typeof(string));
                col.MaxLength=30;
                col=tb1.Columns.Add("Phone",typeof(string));
                col.MaxLength=24;
                tb1.PrimaryKey=new DataColumn[]...{tb1.Columns["CustomerID"]};

                    //创建订单表
                tb1=ds.Tables.Add("Orders");
                col=tb1.Columns.Add("OrderID",typeof(int));
                col.AutoIncrement = true;
                col.AutoIncrementSeed=-1;
                col.AutoIncrementStep=-1;
                col.ReadOnly = true;
                col=tb1.Columns.Add("CustomerID",typeof(string));
                col.AllowDBNull=false;
                col.MaxLength=5;
                tb1.Columns.Add("EmployeeID",typeof(int));
                tb1.Columns.Add("OrderDate",typeof(DateTime));
                tb1.PrimaryKey=new DataColumn[]...{tb1.Columns["OrderID"]};

                   //创建订单详细信息表
                tb1=ds.Tables.Add("Order Details");
                tb1.Columns.Add("OrderID",typeof(int));
                tb1.Columns.Add("ProductID",typeof(int));
                col=tb1.Columns.Add("UnitPrice",typeof(Decimal));
                col.AllowDBNull=false;
                col=tb1.Columns.Add("Quantity",typeof(int));
                col.AllowDBNull=false;
                col.DefaultValue=1;
                col=tb1.Columns.Add("Discount",typeof(Decimal));
                col.DefaultValue=0;
                tb1.Columns.Add("ItemTotal",typeof(Decimal),
                    "UnitPrice*Quantity*(1-Discount)");
                tb1.PrimaryKey=new DataColumn[]...{tb1.Columns["OrderID"],
                    tb1.Columns["ProductID"]};
                    //创建外鍵约束
                fk=new ForeignKeyConstraint(ds.Tables["Customers"].Columns["CustomerID"],
                    ds.Tables["Orders"].Columns["CustomerID"]);
                fk=new ForeignKeyConstraint(ds.Tables["Orders"].Columns["OrderID"],
                    ds.Tables["Order Details"].Columns["OrderID"]);
                ds.Tables["Order Details"].Constraints.Add(fk);
              
            }
            catch (SqlException es)
            ...{
                MessageBox.Show(es.Message);
            }
        }