Professional ASP.NET source code

				
				
				
				
				
				
				
				Connection string: 
				Books SELECT command: 
				Authors SELECT command: 
				Prices SELECT command: 
				 
				
				
				
					public DataSet BooksDataSet(string strConnect, string strWhere)
					{
						outConnect.InnerText = strConnect;  //display connection string
				
						// specify the SELECT statement to extract the BookList data
						string strSelectBooks = "SELECT * FROM BookList WHERE " + strWhere;
						outSelectBooks.InnerText = strSelectBooks;   // and display it
				
						// specify the SELECT statement to extract the BookAuthor data
						string strSelectAuthors = "SELECT * FROM BookAuthors WHERE " + strWhere;
						outSelectAuthors.InnerText = strSelectAuthors;   // and display it
				
						// specify the SELECT statement to extract the BookPrices data
						string strSelectPrices = "SELECT * FROM BookPrices WHERE " + strWhere;
						outSelectPrices.InnerText = strSelectAuthors;   // and display it
				
						// declare a variable to hold a DataSet object
						// note that we have to create it outside the Try..Catch block
						// as this is a separate block and so is a different scope
						DataSet objDataSet = new DataSet();
				
						try
						{
				
							// create a new Connection object using the connection string
							OleDbConnection objConnect = new OleDbConnection(strConnect);
				
							// create a new Command object
							OleDbCommand objCommand = new OleDbCommand();
				
							// set the properties
							objCommand.Connection = objConnect;
							objCommand.CommandType = CommandType.Text;
							objCommand.CommandText = strSelectBooks;
				
							// create a new DataAdapter object
							OleDbDataAdapter objDataAdapter = new OleDbDataAdapter();
							// and assign the Command object to it
							objDataAdapter.SelectCommand = objCommand;
				
							// get the data from the "BookList" table in the database and
							// put it into a table named "Books" in the DataSet object
							objDataAdapter.Fill(objDataSet, "Books");
				
							// change the SELECT statement in the ADOCommand object
							objCommand.CommandText = strSelectAuthors;
							// then get data from "BookAuthors" table into the DataSet
							objDataAdapter.Fill(objDataSet, "Authors");
				
							// and do the same again to get the "BookPrices" data
							objCommand.CommandText = strSelectPrices;
							objDataAdapter.Fill(objDataSet, "Prices");
				
							// declare a variable to hold a DataRelation object
							DataRelation objRelation;
				
							// create a Relation object to link Books and Authors
							objRelation = new DataRelation("BookAuthors",
													objDataSet.Tables["Books"].Columns["ISBN"],
													objDataSet.Tables["Authors"].Columns["ISBN"]);
							// and add it to the DataSet object's Relations collection
							objDataSet.Relations.Add(objRelation);
				
							// now do the same to link Books and Prices
							objRelation = new DataRelation("BookPrices",
													objDataSet.Tables["Books"].Columns["ISBN"],
													objDataSet.Tables["Prices"].Columns["ISBN"]);
							objDataSet.Relations.Add(objRelation);
						}
						catch (Exception objError)
						{
							// display error details
							outError.InnerHtml = "* Error while accesing data."
											+ objError.Message + "" + objError.Source;
							// return Nothing on error
							return null;
						}
				
						// display a success message
						outError.InnerHtml = "DataSet created and loaded.";
				
						// return our new disconnected DataSet object
						return objDataSet;
				
					}