Public Class Form1
Private Sub btnlogin_Click(sender As Object, e As EventArgs) Handles btnlogin.Click
Dim con As New SqlClient.SqlConnection(MYConnection.MYconnectionString)
con.Open()
Dim dr As SqlClient.SqlDataReader
Dim cmd As New SqlClient.SqlCommand("select * from [User] where UserName=" + txtuser.Text + " and UserPass= " + txtpassword.Text + "", con)
dr = cmd.ExecuteReader
If dr.Read Then
MsgBox("Welcome")
End If
con.Close()
End Sub
End Class
This is my code from my login form.. whenever i run the program and enter my username and password this will happen :
This is MyConnection.vb that i use to connect to my database
Public Class MYConnection
Public Shared MYconnectionString As String = "Server=CLAIRETUMLOS\SQLEXPRESS;Database=Capstone;Integrated Security=True;"
End Class
here is my dbo.User table
You are missing a ' for string field, but i advise you to use Parameters to avoid SQL injections, like this:
Private Sub btnlogin_Click(sender As Object, e As EventArgs) Handles btnlogin.Click
Dim con As New SqlClient.SqlConnection(MYConnection.MYconnectionString)
con.Open()
Dim dr As SqlClient.SqlDataReader
Dim cmd As New SqlClient.SqlCommand("select * from [User] where UserName=#UserName and UserPass=#UserPass", con)
cmd.Parameters.AddWithValue("#UserName", txtuser.Text)
cmd.Parameters.AddWithValue("#UserPass", txtpassword.Text)
dr = cmd.ExecuteReader
If dr.Read Then
MsgBox("Welcome")
End If
con.Close()
End Sub
Related
I am trying to create a login system for a revision app. However, I was wondering if there was a way where everyone can have separate accounts.
Private Sub Btnlogin_Click(sender As Object, e As EventArgs) Handles Btnlogin.Click
Dim sqlstring As String
sqlstring = "select * FROM login where username = '" & txtusername.Text & "'"
connection.Open()
dataadapter = New OleDb.OleDbDataAdapter(sqlstring, connection)
dt.Clear()
dataadapter.Fill(dt)
connection.Close()
If dt.Rows.Count = 0 Then
MsgBox("no such user")
Exit Sub
End If
If dt.Rows(0)(2) = Txtpassword.Text Then
Flashcard.Show()
Else
Txtpassword.Text = ""
txtusername.Text = ""
MsgBox("Invalid username and password combination")
End If
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Register.Show()
End Sub
That's the code I have if a user already has an account.
Imports System.Data.OleDb
Public Class Register
Dim pro As String
Dim connstring As String
Dim command As String
Dim myconnection As OleDbConnection = New oledbconnection
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
pro = "provider=microsoft.ACE.OLEDB.12.0;Data Source=flashcard login.accdb"
connstring = pro
myconnection.ConnectionString = connstring
myconnection.Open()
command = " insert into login ([username],[password]) values ('" & TextBox1.Text & "','" & TextBox2.Text & "')"
Dim cmd As OleDbCommand = New OleDbCommand(command, myconnection)
cmd.Parameters.Add(New OleDbParameter("username", CType(TextBox1.Text, String)))
cmd.Parameters.Add(New OleDbParameter("password", CType(TextBox1.Text, String)))
MsgBox("You have successfully signed up!")
Form1.Show()
Try
cmd.ExecuteNonQuery()
cmd.Dispose()
myconnection.Close()
TextBox1.Clear()
TextBox2.Clear()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
End Class
That's the code if the user presses the register button (does not have an account).
This code works where the user can succesfully login or register, but the problem is that everyone will have the same windows form. So, I was wondering if there was a way to make each windows form unique to each user?
You can declare and initialize a variable on the same line. The only information you need is if the userName and password exist in the database. Don't pull down data your don't need. You can get this with Count.
Always declare and dispose the connection and command it the method where they are used. Both of these objects need to be disposed so that their unmanaged resources can be released. Using... End Using blocks handle this.
Always use parameters to avoid sql injection. In OleDb the order that the parameters appear in the sql string must match the order that they are added to the parameters collection.
Don't open the connection until directly before the .Execute...
Private ConStr As String = "provider=microsoft.ACE.OLEDB.12.0;Data Source=flashcard login.accdb" '"Your connection string"
Private Sub Btnlogin_Click(sender As Object, e As EventArgs) Handles Btnlogin.Click
Dim rowCount As Integer
Dim sqlstring = "select Count(*) FROM login where [username] = #UserName ANd [password] = #password;"
Using connection As New OleDbConnection(ConStr),
cmd As New OleDbCommand(sqlstring, connection)
cmd.Parameters.Add("#UserName", OleDbType.VarChar).Value = txtusername.Text
connection.Open()
rowCount = CInt(cmd.ExecuteScalar)
End Using
If rowCount = 0 Then
MsgBox("no such user")
Else
Flashcard.Show()
End If
End Sub
Same ideas for the insert. A text box's Text property is always a String so you don't have to convert it.
You are not doing the parameters correctly. You are not using these parameters because the don't appear in the CommandText
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim Command = " insert into login ([username],[password]) values (#UserName, #Password);"
Try
Using myconnection As New OleDbConnection(ConStr),
cmd As OleDbCommand = New OleDbCommand(Command, myconnection)
cmd.Parameters.Add("#UserName", OleDbType.VarChar).Value = TextBox1.Text
cmd.Parameters.Add("#Password", OleDbType.VarChar).Value = TextBox2.Text
myconnection.Open()
cmd.ExecuteNonQuery()
End Using
Catch ex As Exception
MsgBox(ex.Message)
Exit Sub
End Try
MsgBox("You have successfully signed up!")
Form1.Show()
TextBox1.Clear()
TextBox2.Clear()
End Sub
Finally, and very important. You should never store passwords as plain text. Look into salting and encrypting.
I currently doing the changepassword function in my vb.net project, user can click change password to change their password
But my code doesnt update correctly , it will show "updated" but when i go to my database access table the data still remain the same
Imports System.Data.OleDb
Imports System.Data.SqlClient
Imports System.IO
Public Class frmUserDetail
Dim ds As New DataSet
Dim dt As New DataTable
Dim cmd As SqlCommand
Dim con As SqlConnection
Dim da As New OleDbDataAdapter
Dim conn As New OleDbConnection
Private Sub FrmUserDetail_Load(sender As Object, e As EventArgs) Handles MyBase.Load
conn.ConnectionString = ("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=..\phoneOnline.accdb;Persist Security Info=false;")
loadUserDetail()
txtUserName.Enabled = False ' set it to false so user cannot do shit with it
End Sub
Public Sub loadUserDetail()
conn.ConnectionString = ("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=..\phoneOnline.accdb;Persist Security Info=false;")
Dim cmd As OleDbCommand
Dim userName As String = frmMain.lblUserLogin.Text
'specify name of the user
Dim search As String = "SELECT * from tblUser WHERE UserName= '" + userName + "'"
cmd = New OleDbCommand(search)
cmd.Connection = conn
Dim dtt As New DataTable()
Dim daa As New OleDbDataAdapter(cmd)
daa.Fill(dtt)
If dtt.Rows.Count() > 0 Then
txtUserName.Text = dtt.Rows(0)(0).ToString 'show the userName
txtUserPassword.Text = dtt.Rows(0)(1).ToString 'show the password of the user
txtEmail.Text = (dtt.Rows(0)(2).ToString) 'show user email
Else
MsgBox("You are currently login as a guest")
End If
End Sub
Private Sub changePassword()
If cbChangePassword.Checked Then
txtChangePassword.Enabled = True
Else
txtChangePassword.Enabled = Not (True)
End If
End Sub
Private Sub CbChangePassword_CheckedChanged(sender As Object, e As EventArgs) Handles cbChangePassword.CheckedChanged
changePassword()
End Sub
Private Sub BtnUpdate_Click(sender As Object, e As EventArgs) Handles btnUpdate.Click
conn.Open()
Dim cmd As OleDbCommand
Dim sql As String = "UPDATE tblUser SET UserPassword=#userpass,Email=#email WHERE UserName=#userName;"
cmd = New OleDbCommand(sql.ToString, conn)
cmd.Parameters.AddWithValue("#username", txtUserName.Text)
cmd.Parameters.AddWithValue("#userpass", txtChangePassword.Text)
cmd.Parameters.AddWithValue("#email", txtEmail.Text) 'pass the time variable from the form 1 to the parameter
cmd.ExecuteNonQuery()
MsgBox("updated")
conn.Close()
End Sub
Private Sub BtnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click
Me.Hide()
frmMain.Show()
End Sub
End Class
I Expect my database will get updated when i updated it
I want to fill a combobox with items from ms access database.
here's my code..
conn = New OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Ainunandile\Desktop\ElectionDB.mdb;Persist Security Info=False;")
conn.Open()
sqlQry = "SELECT * FROM Candidates where Position='President'"
cmd = New OleDbCommand(sqlQry, conn)
rdr = cmd.ExecuteReader
While rdr.Read()
ComboBox1.Items.Add(rdr("CandidateName").ToString())
End While
however the combobox won't fill up, but if i remove the "where Position ='President'" the code works, can someone help me i've been stuck here for hours.
you can try this i hope this work.
Dim cn As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Ainunandile\Desktop\ElectionDB.mdb;Persist Security Info=False;")
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
cn.Open()
Dim cm As New OleDbCommand("select * from Candidates where Position='President'", cn)
Dim dr As OleDbDataReader = cm.ExecuteReader
While dr.Read
ComboBox1.Items.Add(dr(1).ToString)
End While
dr.Close()
cn.Close()
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim n As Integer = 0
str = "select Vote from vote where party='Green'"
cmd = New SqlCommand(str, con)
con.Open()
dr = cmd.ExecuteReader()
if dr.HasRows Then
dr.Read()
n = dr("Vote").ToString()
n = n + 1
Label8.Text = n.ToString()
End If
str = "update Vote set vote='" + n.ToString() + "' where party='Green'"
cmd = New SqlCommand(str, con)
cmd.ExecuteNonQuery()
dr.Read()
cmd.Dispose()
con.Close()
End Sub
The message seems to be pretty clear. You have to close the DataReader before trying to use the connection for another operation
MSDN says
While the SqlDataReader is being used, the associated SqlConnection is
busy serving the SqlDataReader, and no other operations can be
performed on the SqlConnection other than closing it. This is the case
until the Close method of the SqlDataReader is called. For example,
you cannot retrieve output parameters until after you call Close.
....
dr.Close()
str = "update Vote set vote='" + n.ToString() + "' where party='Green'"
cmd = New SqlCommand(str, con)
cmd.ExecuteNonQuery()
' ??? dr.Read()
cmd.Dispose()
con.Close()
By the way, your whole code could be simplified using an ExecuteScalar to retrieve the last vote value and dumping the DataReader
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim n As Integer = 0
str = "select Vote from vote where party='Green'"
Using cmd = New SqlCommand(str, con)
con.Open()
Dim n as Integer
Dim result = cmd.ExecuteScalar()
if result IsNot Nothing Then
n = Convert.ToInt32(result) + 1
else
n = 1
End If
Label8.Text = n.ToString()
str = "update Vote set vote='" + n.ToString() + "' where party='Green'"
cmd.CommandText = str
cmd.ExecuteNonQuery()
con.Close()
End Using
End Sub
In this scenario you use a global connection object and this should be avoided. Remember that it is always better to create, open, use and destroy the connection when you need to use it. SqlClient classes could use the Connection Pooling infrastructure that could help a lot in managing precious resources like a connection
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
try
Dim n As Integer = 0
str = "select Vote from vote where party='Green'"
cmd = New SqlCommand(str, con)
con.Open()
dr.Close()
dr = cmd.ExecuteReader()
if dr.HasRows Then
dr.Read()
n = dr("Vote").ToString()
n = n + 1
Label8.Text = n.ToString()
End If
str = "update Vote set vote='" + n.ToString() + "' where party='Green'"
cmd = New SqlCommand(str, con)
cmd.ExecuteNonQuery()
dr.Read()
Finally
cmd.Dispose()
con.Close()
End Try
End Sub
Add multiple active results set to your connection string as shown below
Example:
"Server=Server;Database=MyDatabase;Trusted_Connection=True;MultipleActiveResultSets=true;"
I'm creating a login form for vb.net using ms access 2003 as database. But it only checks for the username and bypasses the password. Meaning that if the username is correct and the password doesn't jive with the username, the user can still enter the system. Here is my code:
Try
Dim NoAcc As String
Dim NoAccmod2 As String
Dim NoPas As String
Dim cn As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\db1.mdb;Jet OLEDB:Database Password=nrew123$%^;")
Dim cmd As OleDbCommand = New OleDbCommand("Select * from admintable where AdminName= '" & TextBox4.Text & "' ", cn)
cn.Open()
rdr = cmd.ExecuteReader
If rdr.HasRows Then
rdr.Read()
NoAcc = rdr("AdminName")
NoPas = rdr("AdminPass")
If (TextBox4.Text = NoAcc And TextBox3.Text = NoPas) Then NoAccmod2 = NoAcc
adminview.Show()
Me.Hide()
Else
MsgBox("Incorrect Username/Password")
TextBox4.Clear()
TextBox3.Clear()
End If
Catch
MsgBox("Error logging in, please try again", MsgBoxStyle.Exclamation)
End Try
How do I do it so that it checks both username and password?
You are using a single line IF .. THEN :
If (TextBox4.Text = NoAcc And TextBox3.Text = NoPas) Then NoAccmod2 = NoAcc
so the next line will always be executed:
adminview.Show()
you have to rearrange your IF .. THEN conditions
I will share about login system in vb.net using binding navigator that less of coding. just following the link below!
http://www.tesear.com/2011/09/login-system-in-vbnet.html
You could have BOTH the uname and pword in the database and "WHERE" on both, if you get no record back, then you have your answer.
Try using System.String.Compare(String str1,String str2, Boolean ) As Integer like:
If (System.String.Compare(TextBox4.Text, NoAcc, false) And System.String.Compare(TextBox3.Text, NoPas, false)) Then NoAccmod2 = NoAcc
here is the code:
Imports System.Data
Imports System.Data.OleDb
Public Class Form5
Inherits System.Windows.Forms.Form
Dim mypath = Application.StartupPath & "\login.mdb"
Dim mypassword = ""
Dim conn As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & mypath & ";Jet OLEDB:Database Password=" & mypassword)
Dim cmd As OleDbCommand
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Me.Hide()
Dim sql = "SELECT UserID ,PassID FROM MYTAB WHERE USERID='" & TextBox1.Text & "' AND PASSID='" & TextBox2.Text & "'"
cmd = New OleDbCommand(sql, conn)
conn.Open()
Dim dr As OleDbDataReader = cmd.ExecuteReader
Try
If dr.Read = False Then
MessageBox.Show("Authentication failed...")
Me.Show()
Else
MessageBox.Show("Login successfully...")
Dim frmDialogue As New Form11
frmDialogue.ShowDialog()
End If
Catch ex As Exception
MsgBox(ex.Message)
End Try
conn.Close()
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Close()
End Sub
Private Sub LinkLabel1_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
Me.Hide()
Dim frmDialogue As New Form1
frmDialogue.ShowDialog()
End Sub
Private Sub Form5_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
Dim frm As New Form1
frm.Show()
End Sub
End Class
Try
Dim NoAcc As String
Dim NoPas As String
Dim rdr As OleDbDataReader
Dim cnn As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\mobilestore.accdb;Persist Security Info=False;")
Dim cmd As OleDbCommand = New OleDbCommand("Select * from logindata where Username= '" & TextBox1.Text & "' and password='" & TextBox2.Text & "'", cnn)
'NoAcc = TextBox1.Text
'NoPas = TextBox2.Text
cnn.Open()
rdr = cmd.ExecuteReader
If (rdr.Read()) Then
NoAcc = rdr("Username")
NoPas = rdr("password")
If (TextBox1.Text = NoAcc And TextBox2.Text = NoPas) Then
Adminpage.Show()
Me.Hide()
Else
MsgBox("Incorrect Username/Password")
TextBox1.Clear()
TextBox2.Clear()
End If
End If
Catch
MsgBox("Error logging in, please try again", MsgBoxStyle.Exclamation)
End Try
End Sub