Difference between DataSet And Data Reader

Difference between DataReader, DataTable and DataSet

DataReader
1. Its an connection oriented, whenever you want fetch the data from database that you need the connection. after fetch the data connection is diconnected. 
2. Its an Read only format, you cann't update records. 

DataSet
1. Its connectionless. whenever you want fetch data from database. its connects indirectly to the database and create a virtual database in local system. then disconnected from database.
2. Its easily read and write data from virtual database.

DataTable
A DataTable object represents a single table in the database. It has a name rows and columns.
There is not much difference between dataset and datatable, dataset is just the collection of datatables.

How do I open SQL Server Management Studio?

For SQL Server 2005, click Start -> Run then type sqlwb

This will open SQL Server Management Studio

VB.NET Generate a random string of numbers and letters

Private Sub btn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn.Click
        Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
        Dim r As New Random
        Dim sb As New StringBuilder
        For i As Integer = 1 To 4
            Dim idx As Integer = r.Next(0, 35)
            sb.Append(s.Substring(idx, 1))
        Next
        Label2.Text = sb.ToString
    End Sub

Delete files in directory older than 7 days

Dim directory As New IO.DirectoryInfo("C:\Documents and Settings\CLIENT4\My Documents\log\")
        For Each file As IO.FileInfo In directory.GetFiles
            If (Now - file.CreationTime).Days < 7 Then file.Delete()
        Next

Create Folder In VB.net

 Private Sub Ok_Button_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Ok_Button.Click
                ' Check if folder exists, if not: create it
        If Not Directory.Exists("D:\" & "SandeepKumarYadav") Then
            Directory.CreateDirectory("D:\" &"SandeepKumarYadav")
            ' Folder created message
            MessageBox.Show("Folder created!", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
        Else
            ' Folder already exists
            MessageBox.Show("Folder already exists!", "", MessageBoxButtons.OK, MessageBoxIcon.Stop)
        End If
    End Sub

Opening A URL in vb.net

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        System.Diagnostics.Process.Start("http://www.sandeepsky.blogspot.in")
    End Sub

DateTime.ToString() Patterns

All the patterns:

0	MM/dd/yyyy	08/22/2006
1	dddd, dd MMMM yyyy	Tuesday, 22 August 2006
2	dddd, dd MMMM yyyy	HH:mm Tuesday, 22 August 2006 06:30
3	dddd, dd MMMM yyyy	hh:mm tt Tuesday, 22 August 2006 06:30 AM
4	dddd, dd MMMM yyyy	H:mm Tuesday, 22 August 2006 6:30
5	dddd, dd MMMM yyyy	h:mm tt Tuesday, 22 August 2006 6:30 AM
6	dddd, dd MMMM yyyy HH:mm:ss	Tuesday, 22 August 2006 06:30:07
7	MM/dd/yyyy HH:mm	08/22/2006 06:30
8	MM/dd/yyyy hh:mm tt	08/22/2006 06:30 AM
9	MM/dd/yyyy H:mm	08/22/2006 6:30
10	MM/dd/yyyy h:mm tt	08/22/2006 6:30 AM
10	MM/dd/yyyy h:mm tt	08/22/2006 6:30 AM
10	MM/dd/yyyy h:mm tt	08/22/2006 6:30 AM
11	MM/dd/yyyy HH:mm:ss	08/22/2006 06:30:07
12	MMMM dd	August 22
13	MMMM dd	August 22
14	yyyy'-'MM'-'dd'T'HH':'mm':'ss.fffffffK	2006-08-22T06:30:07.7199222-04:00
15	yyyy'-'MM'-'dd'T'HH':'mm':'ss.fffffffK	2006-08-22T06:30:07.7199222-04:00
16	ddd, dd MMM yyyy HH':'mm':'ss 'GMT'	Tue, 22 Aug 2006 06:30:07 GMT
17	ddd, dd MMM yyyy HH':'mm':'ss 'GMT'	Tue, 22 Aug 2006 06:30:07 GMT
18	yyyy'-'MM'-'dd'T'HH':'mm':'ss	2006-08-22T06:30:07
19	HH:mm	06:30
20	hh:mm tt	06:30 AM
21	H:mm	6:30
22	h:mm tt	6:30 AM
23	HH:mm:ss	06:30:07
24	yyyy'-'MM'-'dd HH':'mm':'ss'Z'	2006-08-22 06:30:07Z
25	dddd, dd MMMM yyyy HH:mm:ss	Tuesday, 22 August 2006 06:30:07
26	yyyy MMMM	2006 August
27	yyyy MMMM	2006 August

The patterns for DateTime.ToString ( 'd' ) :

0

MM/dd/yyyy

08/22/2006

The patterns for DateTime.ToString ( 'D' ) :

0

dddd, dd MMMM yyyy

Tuesday, 22 August 2006

The patterns for DateTime.ToString ( 'f' ) :

0	dddd, dd MMMM yyyy HH:mm	Tuesday, 22 August 2006 06:30
1	dddd, dd MMMM yyyy hh:mm	tt Tuesday, 22 August 2006 06:30 AM
2	dddd, dd MMMM yyyy H:mm	Tuesday, 22 August 2006 6:30
3	dddd, dd MMMM yyyy h:mm	tt Tuesday, 22 August 2006 6:30 AM

The patterns for DateTime.ToString ( 'F' ) :

0

dddd, dd MMMM yyyy HH:mm:ss

Tuesday, 22 August 2006 06:30:07

The patterns for DateTime.ToString ( 'g' ) :

0	MM/dd/yyyy HH:mm	08/22/2006 06:30
1	MM/dd/yyyy hh:mm	tt 08/22/2006 06:30 AM
2	MM/dd/yyyy H:mm	08/22/2006 6:30
3	MM/dd/yyyy h:mm tt	08/22/2006 6:30 AM

The patterns for DateTime.ToString ( 'G' ) :

0

MM/dd/yyyy HH:mm:ss

08/22/2006 06:30:07

The patterns for DateTime.ToString ( 'm' ) :

0

MMMM dd

August 22

The patterns for DateTime.ToString ( 'r' ) :

0

ddd, dd MMM yyyy HH':'mm':'ss 'GMT'

Tue, 22 Aug 2006 06:30:07 GMT

The patterns for DateTime.ToString ( 's' ) :

0

yyyy'-'MM'-'dd'T'HH':'mm':'ss

2006-08-22T06:30:07

The patterns for DateTime.ToString ( 'u' ) :

0

yyyy'-'MM'-'dd HH':'mm':'ss'Z'

2006-08-22 06:30:07Z

The patterns for DateTime.ToString ( 'U' ) :

0

dddd, dd MMMM yyyy HH:mm:ss

Tuesday, 22 August 2006 06:30:07

The patterns for DateTime.ToString ( 'y' ) :

0	yyyy MMMM 2006 August

Building a custom DateTime.ToString Patterns

The following details the meaning of each pattern character. Note the K and z character.

d	Represents the day of the month as a number from 1 through 31. A single-digit day is formatted without a leading zero
dd	Represents the day of the month as a number from 01 through 31. A single-digit day is formatted with a leading zero
ddd	Represents the abbreviated name of the day of the week (Mon, Tues, Wed etc)
dddd	Represents the full name of the day of the week (Monday, Tuesday etc)
h	12-hour clock hour (e.g. 7)
hh	12-hour clock, with a leading 0 (e.g. 07)
H	24-hour clock hour (e.g. 19)
HH	24-hour clock hour, with a leading 0 (e.g. 19)
m	Minutes
mm	Minutes with a leading zero
M	Month number
MM	Month number with leading zero
MMM	Abbreviated Month Name (e.g. Dec)
MMMM	Full month name (e.g. December)
s	Seconds
ss	Seconds with leading zero
t	Abbreviated AM / PM (e.g. A or P)
tt	AM / PM (e.g. AM or PM
y	Year, no leading zero (e.g. 2001 would be 1)
yy	Year, leadin zero (e.g. 2001 would be 01)
yyy	Year, (e.g. 2001 would be 2001)
yyyy	Year, (e.g. 2001 would be 2001)
K	Represents the time zone information of a date and time value (e.g. +05:00)
z	With DateTime values, represents the signed offset of the local operating system's   time zone from Coordinated Universal Time (UTC), measured in hours. (e.g. +6)
zz	As z but with leadin zero (e.g. +06)
zzz	With DateTime values, represents the signed offset of the local operating system's   time zone from UTC, measured in hours and minutes. (e.g. +06:00)
f	Represents the most significant digit of the seconds fraction; that is, it represents the tenths of a second in a date and time value.
ff	Represents the two most significant digits of the seconds fraction; that is, it represents the hundredths of a second in a date and time value.
fff	Represents the three most significant digits of the seconds fraction; that is, it represents the milliseconds in a date and time value.
ffff	Represents the four most significant digits of the seconds fraction; that is, it represents the ten thousandths of a second in a date and time value. While it is possible to display the ten thousandths of a second component of a time value, that value may not be meaningful. The precision of date and time values depends on the resolution of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock's resolution is approximately 10-15 milliseconds.
fffff	Represents the five most significant digits of the seconds fraction; that is, it represents the hundred thousandths of a second in a date and time value. While it is possible to display the hundred thousandths of a second component of a time value, that value may not be meaningful. The precision of date and time values depends on the resolution of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock's resolution is approximately 10-15 milliseconds.
ffffff	Represents the six most significant digits of the seconds fraction; that is, it represents the millionths of a second in a date and time value. While it is possible to display the millionths of a second component of a time value, that value may not be meaningful. The precision of date and time values depends on the resolution of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock's resolution is approximately 10-15 milliseconds.
fffffff	Represents the seven most significant digits of the seconds fraction; that is, it represents the ten millionths of a second in a date and time value. While it is possible to display the ten millionths of a second component of a time value, that value may not be meaningful. The precision of date and time values depends on the resolution of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock's resolution is approximately 10-15 milliseconds.
F	Represents the most significant digit of the seconds fraction; that is, it represents the tenths of a second in a date and time value. Nothing is displayed if the digit is zero.
:	Represents the time separator defined in the current DateTimeFormatInfo..::.TimeSeparator property. This separator is used to differentiate hours, minutes, and seconds.
/	Represents the date separator defined in the current DateTimeFormatInfo..::.DateSeparator property. This separator is used to differentiate years, months, and days.
"	Represents a quoted string (quotation mark). Displays the literal value of any string   between two quotation marks ("). Your application should precede each quotation mark with an escape character (\).
'	Represents a quoted string (apostrophe). Displays the literal value of any string between two apostrophe (') characters.
%c	Represents the result associated with a c custom format specifier, when the custom date and time format string consists solely of that custom format specifier. That is, to use the d, f, F, h, m, s, t, y, z, H, or M custom format specifier by itself, the application should specify %d, %f, %F, %h, %m, %s, %t, %y, %z, %H, or %M. For more information about using a single format specifier, see Using Single Custom Format Specifiers.

||\c || Represents the escape character, and displays the character "c" as a literal when that character is preceded by the escape character (\). To insert the backslash character itself in the result string, the application should use two escape characters ("\\").

Any other character copies any other character to the result string, without affecting formatting. ||