Database and Asp.Net

The technologies that helps retrieving the  data from database have been on a progressive trend, and been gone through ODBC, DAO, RDO, ADO etc. The asp net uses ADO.Net and without ADO..Net.

The technologies those do not uses ADO.Net are the followings

  • SqlDataSource control : It is a rich control and do not need ADO.Net, rather ADO.Net uses this control underneath , and SqlDatasource support any database that has AD.Net provider.
    • GridView uses SqlDataSource control.
    • SqlDataSource control mostly relies on ObjectDadaSource ( useually created with a Class and placed in App_Data
  • LINQ to SQL
  • Profiles

Ref Mathews APress 9781

 

As you can see in Figure 8-3, each item in the DataSet.Tables collection is a DataTable. The
DataTable contains its own collections—the Columns collection of DataColumn objects (which
describe the name and data type of each field) and the Rows collection of DataRow objects
(which contain the actual data in each record).
 

Each record in a DataTable is represented by a DataRow object. Each DataRow object represents
a single record in a table that has been retrieved from the data source. The DataRow is the
container for the actual field values. You can access them by field name, as in myRow["FieldName"].
Always remember that the data in the data source is not touched at all when you work with the
DataSet objects. Instead, all the changes are made locally to the DataSet in memory. The DataSet
never retains any type of connection to a data source.
 

The DataSet also has methods that can write and read XML data and schemas and has methods
you can use to quickly clear and duplicate data. Table 8-1 outlines these methods. You’ll learn more
about XML in Chapter 14.

Connection String

Command Class

Disconnected data

With ADO.Net, the data you retrieve is not connected with the data source or database. Any change in the DataSet that copied the data from the database or data source, can safely be manipulated, and at the end, if it is required, you can sync with the original data source in a single batch operation. (page 311 Mathew 0781 )

DataSet is easier to use than a DataReader include the following:

  • When you need a convenient package to send the data to another component (for example, if you’re sharing information with other components or distributing it to clients through a webservice).
  • When you need a convenient file format to serialize the data to disk (the DataSet includes built-in functionality that allows you to save it to an XML file).
  • When you want to navigate backward and forward through a large amount of data. Forexample, you could use a DataSet to support a paged list control that shows a subset of information at a time.
  • The DataReader, on the other hand, can move in only one direction:forward.
  • When you want to navigate among several different tables. The DataSet can store all these tables, and information about the relations between them, thereby allowing you to create easy master-detail pages without needing to query the database more than once.
  • When you want to use data binding with user interface controls. You can use a DataReader for data binding, but because the DataReader is a forward-only cursor, you can’t bind your data to multiple controls. You also won’t have the ability to apply custom sorting and filtering criteria, like you can with the DataSet.
  • When you want to manipulate the data as XML.
  • When you want to provide batch updates. For example, you might create a web service that allows a client to download a DataTable full of rows, make multiple changes, and then resubmit it later. At that point, the web service can apply all the changes in a single operation (assuming no conflicts occur).
     

The DataSet also supports( mathew page 313)
data binding, which allows you to display your information in advanced data controls such as the
GridView. For that reason, most web applications retrieve data into the DataSet but perform direct
updates using straightforward commands.

Using the DataSet, an application on the user’s laptop can store disconnected data locally and serialize it to an
XML file. This allows the sales associate to build new orders using the cached data, even when no
Internet connection is available. The new data can be submitted later when the user reconnects to
the system.

 

Data Adapter Class

 

Filling A dataSet

string connectionString = WebConfigurationManager.ConnectionStrings["Northwind"].ConnectionString;
SqlConnection con = new SqlConnection(connectionString);
string sql = "SELECT * FROM Employees";