ADO.Net Modelo para acesso a dados nas aplicação.Net Componentes: DataSet.Net Data providers: Connection Command DataReader DataAdapter

Arquitectura.Net

Accessing Data with ADO.NET Database 4.Return the DataSet to the Client 5.Client manipulates the data 2.Create the SqlConnection and SqlDataAdapter objects 3.Fill the DataSet from the DataAdapter and close the connection SqlDataAdapter SqlConnection List-Bound Control 1.Client makes request Update the DataSet 7.Use the SqlDataAdapter to open the SqlConnection, update the database, and close the connection Client Web server DataSet

.Net Data Providers SQL Server - System.Data.SqlClient OLE DB - System.Data.OleDb ODBC - System.Data.Odbc Oracle - System.Data.OracleClient. Connection Estabelece a comunicação com a fonte de dados Command Executa um comando na fonte de dados DataReader Lê sequencialmente de uma fonte de dados – só leitura DataAdapter Preenche um DataSet Implementam os Objectos:

Connection System.Data.SqlClient.SqlConnection myConnectionStr = "Initial Catalog=Northwind;Data Source=localhost; Integrated Security=SSPI;"; SqlConnection myConnection = new SqlConnection(myConnectionString); myConnection.Open();... myConnection.Close(); SqlConnection (SqlServer) System.Data.OleDb.OleDbConnection myConnection; strpath=Server.MapPath(loja.mdb"); myConnectionStr="Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + strpath; myConnection=new OleDbConnection(myConnectionStr); myConnection.Open();... myConnection.Close(); OleDbConnection (p.e. Access)

Data Commands É uma instância das classes OleDbCommand, SqlCommand, OdbcCommand, ou OracleCommand Contém uma referência para uma instrução SQL ou stored procedure Propriedades: Connection CommandText Parameters Métodos ExecuteReader – Devolve registos para um DataReader, usado em Select ExecuteNonQuery – Usado em Insert, Update e Delete

Data Commands private System.Data.OleDb.OleDbConnection myConnection; private System.Data.OleDb.OleDbCommand cmd; String myConnectionstr="Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + strpath; String strsql="Insert into Produtos (IdCat,NomeProd,Preco) Values ('1','" + nomeprod + "'," + "'" + preco +"')" ; myConnection=new System.Data.OleDb.OleDbConnection(myConnectionstr); cmd.Connection.Open(); cmd=new OleDbCommand (strsql,myConnection); (*) cmd.ExecuteNonQuery(); myConnection.Close(); (*) cmd=new System.Data.OleDb.OleDbCommand(); cmd.Connection=myConnection; cmd.CommandText=strsql;

DataReader Permite ler de uma fonte de dados forward-only e read-only Criado através do método executeReader de um objecto Command Pode ser associado ao DataSource de Server Controls string mySelectQuery = "SELECT OrderID, CustomerID FROM Orders"; OleDbConnection myConnection = new OleDbConnection(myConnString); OleDbCommand myCommand = new OleDbCommand(mySelectQuery,myConnection); myConnection.Open(); OleDbDataReader myReader; myReader = myCommand.ExecuteReader(); DataGrid1.DataSource=dtreader; DataGrid1.DataBind(); Web Form DataReader

Métodos: Read – devolve uma linha do resultado do query if (myReader.HasRows) while (myReader.Read()) {... }

SQL Server 2000 DataSet DataTable Physical storage OleDb Database SqlDataAdapter SqlConnection DataTable Web server memory OleDbDataAdapter OleDbConnection What is a Dataset?

Data Adapters sp_SELECT Command SelectCommandUpdateCommandInsertCommandDeleteCommand DataAdapter Command Connection sp_UPDATEsp_INSERTsp_DELETE Database DataSet DataReader

Store the query in a DataAdapter The DataAdapter constructor sets the SelectCommand property Set the InsertCommand, UpdateCommand, and DeleteCommand properties if needed Creating a DataAdapter da.SelectCommand.CommandText da.SelectCommand.Connection da.SelectCommand.CommandText da.SelectCommand.Connection SqlDataAdapter da = new SqlDataAdapter ("select * from Authors",conn); SqlDataAdapter da = new SqlDataAdapter ("select * from Authors",conn);

Creating a DataSet Create and populate a DataSet with DataTables –Fill method executes the SelectCommand Access a DataTable DataSet ds = new DataSet(); da.Fill(ds, "Authors"); DataSet ds = new DataSet(); da.Fill(ds, "Authors"); ds.Tables["Authors"].Rows.Count; string str=""; foreach(DataRow r in ds.Tables["Authors"].Rows) { str += r[2]; str += r["au_lname"]; } string str=""; foreach(DataRow r in ds.Tables["Authors"].Rows) { str += r[2]; str += r["au_lname"]; }