Explain DataView

A DataView enables us to create different views of the data stored in a DataTable, a capability that is often used in data-binding applications. Using a DataView, we can expose the data in a table with different sort orders, and we can filter the data by row state or based on a filter expression.

It provides a means to filter and sort data within a data table.

Example:
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 XYZ
myDataView.RowFilter = "CustomerID=XYZ";

Difference between ExecuteNonQuery, ExecuteScaler, ExecuteReader

Difference Angle	ExecuteNonQuery	ExecuteScaler	ExecuteReader
About	After Executing Sql statement Returns number of rows affected	Returns Single value, Executes first column first row only	Send the Command text to connection and builds a SqlDataReader.
When we use	ExecuteNonQuery is used to perform Catalog operation like Creating table in database or Changing of data in tables (without using Dataset) by using Insert, Update, Delete, create	Selecting only single fields like count field	When we manipulating with DataReader it used, Sending SQL Select statements to a database, Invoking Stored Procedures
Example	Example: SqlCommand cmd = new SqlCommand("Insert Into SampleTable Values('1','2')",con); //con is the connection object con.Open(); cmd.ExecuteNonQuery(); //The SQL Insert Statement gets executed This method returns no data at all. It is used majorly with Inserts and Updates of tables. It is used for execution of DML commands.	Example : select count(*) from emp ExecuteScalar is used to get aggregate value. ExecuteScalar will return only one value that is first column value of the first row in the executed query. Example 2: cmd.CommandText = "Select Name, DOB, from Emp where ID=1"; Dim strName As string = cmd.ExecuteScalar.ToString This returns one value only, no recordsets.	Example: SqlConnection con = new SqlConnection(constr); //constructor can be connection of string. SqlCommand cmd = new SqlCommand ("select * from emp", con); con.Open(); SqlDataReader dr = cmd. ExecuteReader (CommandBehavior. CloseConnection); while(dr.Read()) { Console.WriteLine (dr.GetString(0)); } dr.Close(); //Implicitly closes the connection because CommandBehavior. CloseConnection was specified. ExecuteReader is used to get set records by specified query