Agenda :-
1)
difference between Connected Architecture and
Disconnected Architecture
2)
Data
Reader and DataSet.
3)
Feature
of DataSet
4)
Working
with DataSet
5)
Methods
of DataAdapter.
6)
Accessing
Data From DataSet.
7)
DataTable
8)
Referring
to a cell under DataTable.
Lets we start with Details
ADO.NET Provide two different models for
accessing data from Data Source.
1)Connection Oriented Architecture :-
2)Dis-Connection Oriented Architecture :-
1)Connection
Oriented Architecture :-
In this
case we require a continuous connection with the Data Source for accessing data
in it.
Here “DataReader” Class is use for holding data on Client
Machines.
2)Dis-Connection Oriented Architecture :-
In this
case we do not require a continuous
connection with the Data Source for accessing data .
Here “DataSet” Class is use for holding data on Client
Machines.
DataSet :-
It is a class present under “System.Data” namespace design for holding and managing data on
client machines apart from DataReader.
Features Of DataSet:-
1)it is also
capable of holding multiple tables.
2)it is a
designed Dis-Connected
architecture,which doesn’t
require any permanent connection with DataSource for holding data.
3)It Provide
scrollable navigation to data,that allows us to move in any direction.
i.e. eighter top to bottom or bottom to top.
4)it is updatable i.e . changes can be performed to
data present in it and also send changes back to DB.
Working
With DataSet :-
This class
that is responsible for loading of data into a DataReader from DataSource is
command.
In the same way,DataAdapter is the class used
for Communication between DataSource and DataSet.
Simply
DataReader < - Command
-> DataSource.
DataSet
<->DataAdapter
<->DataSource.
Methods of DataAdapter :-
1) Fill(DataSet ds,string TableName).
2) Update (DataSet ds,string TableName)
Fill is the
method to Load data from DataSource into DataSet.
Update is to
transfer data from a DataSet to DataSource.
DataAdapter is internally collection of 4 Method:-
1)Select Command.
2)Insert Command.
3)Update Command.
4)Delete Command.
When we
call Fill() method of
Adaper,Following action take place internally.
1)Open a
connection with DataSource.
2)Execute the Select
command under it on the DataSource and loads data from table to DataSet.
3)Close the Connection.
As a DataSet
is updatable ,changes can be made to data that is loaded into it like adding
,modifying and deleting records.
After making
all the changes to data in dataset and if we want to send those changes back to
datasource call Update ( ) method on dataadapter which perform following,
1)Re Open a Connection with DataSource.
2)Changes that are made in dataset will be sent back
to table where in this process it will make use of insert,update and delete
command of DataAdapter.
3)Close the Connection.
Accessing Data From DataSet:-
DataReader provides us Pointer
vases access to th data ,so we can get data only in a sequencial order,where as
dataset provides us index based access to data so we can get the data from any
location .
Dataset is a collection of table where each table is the represented as
class datatable and identified by the index position .
DataTable :-
Datatable is the collection of tables.
Following syntax is used for DataTable
<DataSet>.Tables[Index]/[Name]
Eg
Ds.Tables[0]
Or
Ds.tables[“Company”]
Every DataTable is again Collection of Rows and
Columns where each row is represented as
a class DataRow and identified by its index position.
Each column
is represented as class DataColumn and identified by it
index position or Name.
DataRow:
It is
collection rows .
Syntax:
<datatable>.Rows[Index].
Eg.
Ds.tables[0].rows[0]
DataColumns:
It is
collection Coumns .
Syntax:
<datatable>.Columns[Index] OR columns[Name]
Eg.
Ds.Tables[0].Column[0]
OR
Ds.Tables[0].Column[“ENO”]
Ds.tables[0].rows[0]
Referring to a Cell under Data Table:
Syntax:
<datatable>.Rows[row] [col]
Eg.
Ds.Tables[0].Rows[0][0]
OR
Ds.Tables[0].Rows[0][“ENO”]
Ds.tables[0].rows[0]
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