Saturday, April 7, 2007

Explain DataView

It provides a means to filter and sort data within a data table.
DataView myDataView = new DataView(myDataSet.Tables["Customers"]);

// Sort the view based on the FirstName column
myDataView.Sort = "CustomerID";

// Filter the dataview to only show customers with the CustomerID of ALFKI
myDataView.RowFilter = "CustomerID='ALFKI'";

Explain DataAdapter Object

It populates dataset from data source. It contains a reference to the connection object and opens and closes the connection automatically when reading from or writing to the database.

SqlDataAdapter daEmp = new SqlDataAdapter( "select EmpID, EmpName, Salary from Employees", conn);

Fill Method
It is used to populate dataset.
example: daEmp.Fill(dsEmp,"Employee");

Update Method
It is used to update database.
example: daEmp.Update(dsEmp,"Employee");

Explain DataSet Object

Dataset is a disconnected, in-memory representation of data. It can contain multiple data table from different database.

They contain multiple Datatable objects, which contain columns and rows, just like normal data base tables. You can even define relations between tables to create parent-child relationships.

DataSet dsEmp = new DataSet();

For more understanding look for DataAdapter Object

Explain DataReader Object

It provides a forward-only, read-only, connected recordset.

It is most efficient to use when data need not to be updated, and requires forward only traverse. In other words, it is the fastest method to read data.


  1. Filling dropdownlistbox.
  2. Comparing username and password in database.

SqlDataReader rdr = cmd.ExecuteReader();

//Reading data

while (rdr.Read())

//Display data

string contact = (string)rdr["ContactName"];
string company = (string)rdr["CompanyName"];
string city = (string)rdr["City"];


What is Command Object

It allows to manipulate database by executing stored procedure or sql statements.

A SqlCommand object allows you to specify what type of interaction you want to perform with a data base.

For example, you can do select, insert, modify, and delete commands on rows of data in a data base table.
SqlCommand cmd = new SqlCommand("select * from Employees", conn);

What is Connection Object

It establishes connection.
The connection helps identify the data base server, the data base name, user name, password, and other parameters that are required for connecting to the data base.

SqlConnection conn = new SqlConnection( "Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI");

What is Data Provider

A set of libraries that is used to communicate with data source. Eg: SQL data provider for SQL, Oracle data provider for Oracle, OLE DB data provider for access, excel or mysql.

What is Data Source

It can be a database, text file, excel spread sheet or an XML file.

Name ADO.NET Objects

  1. Connection Object
  2. Command Object
  3. DataReader Object
  4. DataSet Object
  5. DataAdapter Object

Difference between Dataset and ADO Recordset

A DataSet can represent an entire relational database in memory, complete with tables, relations, and views.
· A DataSet is designed to work without any continuing connection to the original data source.
· Data in a DataSet is bulk-loaded, rather than being loaded on demand.
· There's no concept of cursor types in a DataSet.
· DataSets have no current record pointer You can use For Each loops to move through the data.
· You can store many edits in a DataSet, and write them to the original data source in a single operation.
· Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources.

Difference between ADO and

1. ADO used connected data usage, while used disconnected data environment.
2. ADO used OLE DB to access data and is COM-based, while uses XML as the format for transmitting data to and from your database and web application.
3. In ADO, Record set, is like a single table or query result, while in Dataset, can contain multiple tables from any data source.
4. In ADO, it is sometime problematic because firewall prohibits many types of request, while in there is no such problem because XML is completely firewall-proof.

What is is data access architecture for the Microsoft .NET Framework.

ADO.NET is an object-oriented set of libraries that allows you to interact with data sources. Commonly, the data source is a data base, but it could also be a text file, an Excel spread sheet, or an XML file.

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