Database Operations

ADO .net

ADO.NET is the new database technology of the .NET platform, and it builds on Microsoft ActiveX® Data Objects (ADO).

ADO.NET is a set of classes that expose data access services to the .NET developer. The ADO.NET classes are found inSystem.Data.dll 

ADO.NET is an primary part of the .NET Framework, providing access to relational data,

Overview of ActiveX Data Objects

Data Provider

Data Provider for SQL Server (System.Data.SqlClient). The recommended data provider for SQL Server data

sources is SQL ServerData Provider for OLEDB (System.Data.OleDb).

OLEDB is a COM-based API for database connections. Data Provider for ODBC (System.Data.Odbc).

DODBC is an older standard and is actually not specific to window you can get Unix-based ODBC   

Data Provider for Oracle (System.Data.OracleClient).  oracle DB

Components  of ADO

 Connection object (SqlConnection, OleDbConnection, OdbcConnection, OracleConnection)

Namespace required using System.Data…. ;

Connection String private string constr =" Initial Catalog=Northwind;" + "Data

Source=temp\\MYSQLSERVER;";Create instance of connection

OleDbConnection con = new OleDbConnection(constr);Open Connection

con.Open(); Open a connection when you need it, and Close it as soon as you have finished with it.

Command

 Command object (SqlCommand, OleDbCommand, OdbcCommand, OracleCommand)  Deals with databases. It executes SQL commands on

a database. It sends an SQL command to a database that is specified by an SqlConnection object. We then call instance methods to physically apply the command to the database.

ExecuteNonQuery() method Executes a SQL statement against the connection and

returns the number of rows affected.

DataReader

DataReader object (SqlDataReader, OleDbDataReader, OdbcDataReader, OracleDataReader)

You use the Read method of the DataReader object to obtain a row from the results of the query. You can access each column of the returned row by passing the name or ordinal reference of the column to the DataReader

SqlDataReader reader = command.ExecuteReader();

Data Reader Sample code

SqlCommand command = new SqlCommand( "SELECT CategoryID, CategoryName FROM Categories;", connection); connection.Open();

SqlDataReader reader = command.ExecuteReader();

if (reader.HasRows) { while (reader.Read()) { Console.WriteLine("{0}\t{1}", reader.GetInt32(0), reader.GetString(1)); } } else { Console.WriteLine("No rows found."); } reader.Close();

DataAdapter

DataAdapter object is like a bridge that links the database and a Connection object with the ADO.NET-managedDataSet object through its SELECT and action query Commands. It specifies what data to move into and out of theDataSet

The DataAdapter provides four properties that allow us to control how updates are made to the server: SelectCommand,UpdateCommand,InsertCommand,DeleteComman

Fill (populates a DataSet with data).FillSchema (queries the database for schema information

that is necessary to update).Update (to change the database, DataAdapter calls

the DeleteCommand, the InsertCommand and theUpdateCommand properties).

DataSet

The DataSet is similar to an array of disconnected Recordset objects. It supports disconnected data access and operations, allowing greater scalability because you no longer have to be connected to the database all the time.DataSet is a copy of an extracted data being downloaded and cached in the client system.

DataTableCollection object containing null or multiple DataTable objects (Columns, Rows, Constraints).

DataRelationCollection object containing null or multiple DataRelation objects which establish a parent/child relation between two DataTable objects.

DataGrid 

Windows Forms DataGrid control displays data in a series of rows and columns.

DataGridcontrol provides a user interface to ADO.NET DataSets.

displays tabular data and allows for updates to the data source.

DataGrid control to a valid data sourceControl will be automatically populated,

creating columns and rows based on the shape of the data.