This is compiled version(part-1) of ADO.NET Difference FAQS

1. ADO.NET Difference FAQs-1
1. What are the differences between DataReader and DataAdapter?
S.No DataReader DataAdapter
1 Works in Connected Mode Works in Disconnected Mode
2 Can have only one record at a Can have more than 1 records
time
3 Is ForwardOnly and Readonly Can navigate front and back and
editable
4 Faster Slower
2. What are the differences between DataSet and DataReader?
S.No DataSet DataReader
1 The data store whose records You can read data from datareader
have to be manipulated can be only if the connection to data store
disconnected. exists.
2 You have the provision to cache Caching of data is not possible.
data fetched from data store
when using dataset.
3 Dataset objects have XML XML Support is not provided by
Support. datareader.
4 A single dataset object can Datareader can read records
contain collection of datatable fetched by a command object
objects wherein each datatable containing a single query. If you
object refers to a table in the have to fetch data from multiple
datastore. Hence you can tables, then datareader is not
manipulate on multiple tables advantageous when compared to
using a dataset. dataset.
5 Using dataset, you can read the While reading records, you can
records fetched in any order. iterate only in forward direction.
6 Performance wise, dataset is Datareader gives high performance
slow because it has multiple and records can be fetched faster
tables which in turn include when compared to dataset.
multiple rows, columns and
constraints.
3. What is the difference between DataSet.Copy() and DataSet.Clone()?
S.No DataSet.Copy() DataSet.Clone()
1 DataSet.Copy() copies both the DataSet.Clone() copies the
structure and data structure of the DataSet, including
all DataTable schemas, relations,

2. and constraints and it does not copy
any data
4. What are the differences between RecordSet and DataSet?
S.No RecordSet DataSet
1 RecordSet provides data of one DataSet is a data structure which
row at an instant represents the complete table data
at the same time
2 RecordSet always needs an DataSet needs connection only for
Open connection to read the retrieving the data. After retrieve the
data from data sources data connection is not necessary
3 RecordSet is able to load the DataSet has the capability to store
structure and data of only one the structure and data of multiple
table at a time tables at a time
4 RecordSet does not support DataSet enforces data integrity by
constraints of Databases using Constraints
5. What are the differences between ADO and ADO.Net?
S.No ADO ADO.Net
1 It is a COM based library. It is a CLR based library.
2 Classic ADO requires active ADO.NET architecture works while the
connection with the data store. data store is disconnected.
3 Locking feature is available. Locking feature is not available.
4 Data is stored in binary format. Data is stored in XML.
5 XML integration is not possible. XML integration is possible.
6 It uses the object named It uses Dataset Object for data access
Recordset to reference data from and representation.
the data store.
7 Using Classic ADO, you can Dataset object of ADO.NET includes
obtain information from one table collection of DataTables wherein each
or set of tables through join. You DataTable will contain records fetched
cannot fetch records from multiple from a particular table. Hence multiple
tables independently. table records are maintained
independently.
8 Firewall might prevent execution ADO.NET has firewall proof and its
of Classic ADO. execution will never be interrupted.
9 Classic ADO architecture includes ADO.NET architecture doesn't include
client side cursor and server side such cursors.
cursor.

3. 10 You cannot send multiple You can send multiple transactions
transactions using a single using a single connection instance.
connection instance.
Reference: http://onlydifferencefaqs.blogspot.in/2012/07/adonet-difference-faqs-1.html
ADO.Net Difference FAQs-2
1.Difference between Typed DataSet and Untyped DataSet
S.No Typed DataSet Untyped DataSet
1 It provides additional methods, It is not as easy to use as strongly
properties and events and thus typed dataset.
it makes it easier to use.
2 They have .xsd file (Xml They do not do error checking at
Schema definition) file the design time as they are filled at
associated with them and do run time when the code executes.
error checking regarding their
schema at design time using
the .xsd definitions.
3 We will get advantage of We cannot get an advantage of
intelliSense in VS. NET. intelliSense.
4 Performance is slower in case Performance is faster in case of
of strongly typed dataset. Untyped dataset.
5 In complex environment, Untyped datasets are easy to
strongly typed dataset's are administer.
difficult to administer.
Typed DataSets use explicit names and DataTypes for their members.
ex:
northwindDataSet.Products.ProductNameColumn.Caption = "pnames";
UnTyped DataSets use table and column collections for their members
ex:
ds.Tables["emp"].Columns["eno"].ReadOnly=true;
2.Difference between DataView and DataTable
S.No DataView DataTable
1 Read-only i.e., DataView can Read/Write i.e., Datatable can be
be used to select the data. used to edit or select or delete or
insert a data.

4. 2 Is a reference to an existing Can be created empty and then
DataTable. Cannot be populated
populated from scratch; must
be instantiated with a
reference to an existing
DataTable.
3 Data is a reference to an Data takes storage space.
existing DataTable, and does
not consume space.
4 Can sort or filter rows without Can add/edit/delete rows, columns,
modifying the underlying data. and data, and all changes are
Rows and columns can be persistent.
hidden and revealed
repeatedly.
5 Can return a DataTable version Can be cloned
of the view
6 A live reference to a Is source data; does not contain
DataTable; any changes in the references
DataTable data is immediately
reflected in the view.
7 Supports calculated columns, Does not support calculated
which are columns with a value columns
calculated on the fly by
combining or manipulating
other columns.
8 Can hide or show selected No row or column hiding
columns
3.Difference between Connected and Disconnected Environment
S.No Connected Environment Disconnected Environment
1 Connected Environment needs Disconnected Environment does
a constantly connection of user not need any connection.
to data source while
performing any operation.
2 Only one operation can be Multiple operations can be
performed at a time in performed.
connection Environment.
3 DataReader is used in DataSet is used in it.
Connection Environment.
4 It is slower in speed. Disconnected Environment has a
good speed.

5. 5 We get updated data in it. There is a problem of dirty read.
Reference: http://onlydifferencefaqs.blogspot.in/2012/08/adonet-difference-faqs-2.html
ADO.NET Difference FAQs-3
1.Difference between ExecuteNonQuery() and ExecuteScalar() methods in ADO.NET
S.No ExecuteNonQuery() ExecuteScalar()
1 It will work with Action Queries It will work with Non-Action Queries
only that contain aggregate functions.
(Create,Alter,Drop,Insert,Updat
e,Delete).
2 It returns the count of rows It returns the first row and first
effected by the Query. column value of the query result.
3 Return type is int Return type is object.
4 Return value is optional and Return value is compulsory and
can be assigned to an integer should be assigned to a variable of
variable. required type.
Example-1 for ExecuteNonQuery Method -Insert:
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
Example-2 for ExecuteNonQuery Method - Update:
public void UpdateEmployeeEmail()
{
SqlConnection conn = new SqlConnection(connString))
String sqlQuery = "UPDATE Employee SET empemail='umar.ali@xyz.com' WHERE
empid=5;
SqlCommand cmd = new SqlCommand(sqlQuery, conn);
try
{
conn.Open();
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{

6. conn.Close();
}
return count;
}
Example-1 for ExecuteScalar Method:
This returns only one value that is first column value of the first row in the executed query
public int getSomeProdId()
{
int count=0;
SqlConnection conn = new SqlConnection(connString))
String sqlQuery = "SELECT COUNT(*) FROM dbo.region";
SqlCommand cmd = new SqlCommand(sqlQuery, conn);
try
{
conn.Open();
//Since return type is System.Object, a typecast is must
count = (Int32)cmd.ExecuteScalar();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
conn.Close();
}
return count;
}
Example-2 for ExecuteScalar Method:
This returns one value only, no recordsets.
cmd.CommandText = "Select Name, DOB, from Emp where ID=1";
Dim strName As string = cmd.ExecuteScalar.ToString
2.Difference between ExecuteNonQuery() and ExecuteReader() methods in
ADO.NET
S.No ExecuteNonQuery() ExecuteReader()
1 It will work with Action Queries It will work with Action and Non-
only Action Queries (Select)
(Create,Alter,Drop,Insert,Updat
e,Delete).

7. 2 It returns the count of rows It returns the collection of rows
effected by the Query. selected by the Query.
3 Return type is int Return type is DataReader.
4 Return value is optional and Return value is compulsory and
can be assigned to an integer should be assigned to an another
variable. object DataReader.
Example-1 for ExecuteNonQuery Method -Insert:
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
Example-2 for ExecuteNonQuery Method - Update:
public void UpdateEmployeeEmail()
{
SqlConnection conn = new SqlConnection(connString))
String sqlQuery = "UPDATE Employee SET empemail='umar.ali@xyz.com' WHERE
empid=5;
SqlCommand cmd = new SqlCommand(sqlQuery, conn);
try
{
conn.Open();
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
conn.Close();
}
return count;
}
Example for ExecuteReader Method:
Here, ExecuteReader is used to get set of records by specified query, namely, "select *
from emp"
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);
//Implicitly closes the connection because CommandBehavior. CloseConnection was
specified.

8. while(dr.Read())
{
Console.WriteLine (dr.GetString(0));
}
dr.Close();
Reference: http://onlydifferencefaqs.blogspot.in/2012/08/adonet-difference-faqs-3.html