ADO.NET Interview Preparation Guide

ADO.NET is a part of the Microsoft .NET Framework. This framework provides the set of classes that deal with data communication between various layers of the software architecture and the database. It provides a continuous access to different data source types such as SQL Server versions 7, 2000, 2005. It also provides connectivity options to data sources through OLE DB and XML. Connectivity may be established with other databases like Oracle, MySQL etc. as well.

ADO.NET has the ability to separate data access mechanisms, data manipulation mechanisms and data connectivity mechanisms.

ADO.NET introduces along with it the disconnected architecture. In a disconnected architecture, data may be stored in a DataSet. It contains providers for connecting to databases, commands for execution and retrieval of results.

The classes for ADO.NET are stored in the DLL System.Data.dll.

yes,we can connect two dataadapters to same datasource using single connection at same time.
There is a technology in ado.net 2.0 called MARS usinng Mars in connection string we can do it.
for eg:
cn.ConnectionString = "server=(local); database=employee; integrated security=sspi; MultipleActiveResultSets=True";

No its not at all possible.

There is a method called Execute Non Query. This method executes the Update, Delete etc. This does not return any rows but will give the number of rows affected.

yes this is possible

If we execute 2 select command either in stored procedure or in select command and then executereader method fired of command object. it return 2 tables in datareader.

like :
string str="Select * from a;select * from b";
cmd.commandtext=str;
dr=cmd.executereader();

Now it return 2 tables in datareader (dr).

// Summary:

// Executes a Transact-SQL statement against the connection and returns the number of rows affected.

// Returns:

// The number of rows affected.

// Summary:

Executes the query, and returns the first column of the first row in the result set returned by the query. Additional columns or rows are ignored.

// Returns:

The first column of the first row in the result set, or a null reference (Nothing in Visual Basic) if the result set is empty.

DataReader DataSet DataTable DataView DataAdapter

Answer: DataAdapter

DataSet ds=new DataSet();

SqlDataAdapter dap=new SqlDataAdapter(Select * from <tablename>,<connection1>);

dap.Fill(ds,"TableOne");

SqlDataAdapter dap1=new SqlDataAdapter(Select * from <tablename>,<connection1>);

dap1.Fill(ds,"tableTwo");

connection String - a string which contains address of the database we want to connect to.