ADO. NET

What is “ADO.Net”? ADO.Net is a new object model for dealing with databases in.Net. Although some of the concepts are similar to the classical ADO, there are some new concepts such as the Dataset. ADO.Net is a new object model for dealing with databases in.Net. Although some of the concepts are similar to the classical ADO, there are some new concepts such as the Dataset.

Introduction to ADO.NET MS-AccessMS-SQLDescription NameSpaceSystem.Data.OleDbSystem.Data.SqlClient ConnectionOleDbConnectionSqlConnection opening a connection to the database CommandOleDbCommandSqlCommand invoking SQL commands or stored procedures RecordSetOleDbDataReaderSqlDataReader connected forward-only access to database DataSetOleDbDataAdapterSqlDataAdapter populating a Dataset. Stored Procedure OleDbParameterSqlParameter specifying parameter to a stored procedure ransactionOleDbTransactionSqlTransaction programming database transactions

Process of using DB (1)  Import Namespace  Make Connection  Open Connection  Send Query  Execute Query  Store result  Populate data in UI  Close connection

Process of using DB (2) SqlConnection conn = new SqlConnection(connstr); //using(SqlConnection conn = new SqlConnection(connstr)) conn.Open(); SqlCommand cmd = new SqlCommand(SQLstr,conn); SqlDataReader reader = cmd.ExecuteReader(); while (reader.Read()) { listBox1.Items.Add(reader[1].ToString()); listBox1.Items.Add(reader[1].ToString());}conn.Close();

Connection(1) Connection String   MS-SQL string connstr = "server=SERVERNAME;uid=USERID;pwd=PASSWORDr;datab ase=DBNAME;"; string connstr = "server=rainnysea;uid=testuser;pwd=testuser;database=Teststd; ";   MS-Acess string connstr = "Provider=ProviderName&Version;Data Source=FileNameOnServer"; string connstr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\\cs440\\Test\\data\\xyz.mdb;";

Connection(2) database connections are an important resource and you should explicitly close the connection. conn = SqlConnection(ConnString); try{ // open the connection to the database conn.Open(); // do something with the database } catch (Exception e) { // report error } finally { conn.Close( ); }

Execute Method on the Command ExecuteNonQuery( ) used when no records are expected in the output e.g., insert or update sql commands. ExecuteReader( ) returns a connected DataReader (actually DataReader interface) ExceuteScalar( ) returns a single row, useful when verifying login for a particular user. ExecuteXmlReader( ) returns an XML reader.

Command(1) – ExecuteScalar() ExecuteScalar() ExecuteScalar() SqlCommand cmd = new SqlCommand(qry, this.con ); new SqlCommand(qry, this.con ); Object obj = cmd.ExecuteScalar(); // returns one row // returns one row

Command(2) – ExecuteReader() ExecuteReader() ExecuteReader() SqlCommand cmd = new SqlCommand(sql,conn); new SqlCommand(sql,conn); SqlDataReader reader = cmd.ExecuteReader();

Command(3) – ExecuteNonQuery() ExecuteNonQuery() ExecuteNonQuery() SqlCommand cmd = new SqlCommand(sql,conn); new SqlCommand(sql,conn); int cntrows = cmd.ExecuteNonQuery();

Data Stored Object(1) DataReader It present a forward-only stream of data to the application. DataSet It is an in-memory representation of a collection of related data tables. It can be generated using the help of a DataAdapter or filled dynamically by the application DataAdapter A class that is used to fill DataSet object from a data source.

Data Stored Object(2) DataReader Data Source Data Reader Application DataSet Data Source Data Set Application 1Application 2 Data Adapter

What is “Data Set”? A Dataset is a disconnected object that can potentially contain all or part of the database including tables, constraints and their relationships. Thus for using databases in web applications, Dataset can provide a much higher performance for mostly read-only type of data. The DataSet class can further use DataTable, DataRow, DataColumn, DataRelation and Constraint classes to define its offline data.

What is ths “Data Adapter”? DataAdapter class acts as the communication point between the DataSet And tha database. DataAdapter class acts as the communication point between the DataSet And tha database. This object is created much the same way as the Command object. This object is created much the same way as the Command object. Fill() method fills DataSet with data obtained from SQL query. Fill() method fills DataSet with data obtained from SQL query.

DataSet(1) DataSet DS = new DataSet(); SqlDataAdapter Adapter = new SqlDataAdapter(qry, conn); new SqlDataAdapter(qry, conn); Adapter.Fill(DS, tblName);

DataGrid Control(1) displays data in a series of rows and columns. displays data in a series of rows and columns. displaying either a single table or the hierarchical relationships between a set of tables. displaying either a single table or the hierarchical relationships between a set of tables. update the data in the bound DataSet, the DataGrid control reflects the changes. update the data in the bound DataSet, the DataGrid control reflects the changes.

DataGrid Control(2) dataGrid.DataSource = dataGrid.DataSource = dataset.DefaultViewManager; dataset.DefaultViewManager; dataGrid.DataSource = dataGrid.DataSource = dataset.Tables[“tablename"].DefaultView ; dataset.Tables[“tablename"].DefaultView ;

DataGrid Control(2) dataset.Relations.Add("CategoryProducts",ds.Tables["category"].Columns["catID"],ds.Tables["product"].Columns["catID"]); //(relationship name, Parent column name, Child column name)

Parameterized query(1)  Construct the SqlCommand command string with parameters.  Declare a SqlParameter object, assigning values as appropriate.  Assign the SqlParameter object to the SqlCommand object's Parameters property.

Parameterized query(2) str = "update tblCategory set catdesc set catdesc where catdesc where catdesc SqlCommand cmd = new SqlCommand(str, Conn()); new SqlCommand(str, Conn()); cmd.Parameters.Add(new

Stored Procedure(1)  A pre-defined, reusable routine that is stored in a database.  Accept input parameters and return multiple values.  Reduced client/server traffic.

Stored Procedure(2) CREATE PROCEDURE as datatype) AS as datatype) AS [ Insert into tblcategory(catdesc) [ Insert into tblcategory(catdesc) // SQL Query // SQL QueryGO

Stored Procedure(3)  create a command object identifying the stored procedure.  set the command object so it knows to execute a stored procedure.  add parameter to command, which will be passed to the stored procedure.

Stored Procedure(4) SqlCommand cmd = new SqlCommand("cateIns", Conn() ); new SqlCommand("cateIns", Conn() ); cmd.CommandType = CommandType.StoredProcedure; CommandType.StoredProcedure;cmd.Parameters.Add (new (new SqlDbType.VarChar,50,"catDesc")); SqlDbType.VarChar,50,"catDesc")); cmd.Parameters[0].Value = newname;