I'm trying to create a Login Form using Visual Basic 2015 in Visual Studio. I've followed the instructions from a video that I've watched, however, an error occurred when I tried to run the code.
Here's the codes I've done so far:
Private Sub picgo1_Click(sender As Object, e As EventArgs) Handles picgo1.Click
openConn()
Dim dr As SqlDataReader
Dim cmd As SqlCommand
Dim sqlsyntax As String
cmd = New SqlCommand
cmd.CommandType = CommandType.Text
cmd.Connection = conn
sqlsyntax = "select * from tblusers where user = '" & txtuser.Text & "' and pass = '" & txtpass.Text & "'"
cmd.CommandText = sqlsyntax
dr = cmd.ExecuteReader()
If dr.HasRows Then
MsgBox("Access Granted! Welcome '" & txtuser.Text & "'")
Else
MsgBox("Access Denied! Incorrect Username or Password!")
End If
conn.Close()
cmd.Dispose()
End Sub
Another for Module
Imports System.Data.SqlClient
Module ModuleConnections
Public conn As SqlConnection
Sub openConn()
Try
conn = New SqlConnection("Data Source=E:\HRIMS\HRIMS V1.0\WINDOWSAPPLICATION2\HRIMSDB.MDF;Integrated security=True")
If conn.State = ConnectionState.Closed Then
conn.Open()
End If
Catch ex As Exception
MsgBox("Connecting to Database Failed" & ex.ToString)
End Try
End Sub
End Module
When I tried to run the form, here is the error I'm getting. Then when I pressed ok, it points me to this line.
I'm still trying to learn, so please don't be too hard on me :D
Thank you in advance.
Try:
Public conn As SqlConnection
Public Sub openConn()
conn = New SqlConnection(CONNECTIONSTRING)
If conn.State = ConnectionState.Closed Then
conn.Open()
End If
Return conn
End Function
Login code:
Using cmd As New SqlCommand("SELECT *
FROM tblusers
WHERE user = #userName
AND pass = #userPass", openConn)
'Parameterize your query to be safe from SQL Injection
cmd.Parameters.AddWithValue("#userName", txtuser.Text)
cmd.Parameters.AddWithValue("#userPass", txtpass.Text)
Using rdr As SqlDataReader = cmd.ExecuteReader(CommandBehavior.SingleResult)
Dim Login As Object = 0
If rdr.HasRows Then
rdr.Read
Login = rdr(Login)
End If
If Login = Nothing Then
MsgBox("Access Denied! Incorrect Username or Password!")
Else
'MsgBox("Access Granted! Welcome '" & txtuser.Text & "'")
MsgBox(String.Format("Access Granted! Welcome {0}!", txtuser.text)
End If
End Using
End Using
I have this module call Procedure , and I want to parametrize it. I'm sending a string as the query to the procedure module . I look already in google but I could not find the answer to my problem.
Procedures.Insert("INSERT INTO Technician (tec_name, tec_email, rol_id) VALUES ('" & txt_tech.text & "', '" & txt_tech_email.text & "', " & cbo_tech_role.selectvalue.tostring & ")", "Technican Add Correct")
========================================
I will probably change it for .....
Procedures.Insert("INSERT INTO Technician (tec_name, tec_email, rol_id) VALUES ('#tech_name', '#tech_email', '#tech_role' ")", "Technican Add Correct")
================ But I dont know where I can Parametrized
Public Sub Insert(query As String, msg As String)
Dim cn As New SqlConnection(cs)
Dim cmd As New SqlCommand
Try
cn.Open()
With cmd
.CommandType = CommandType.Text
.CommandText = query
.Connection = cn
.Parameters.AddValueWith("#tech_name",txt_tech_name.text)
.Parameters.AddValueWith("#tech_email",txt_tech_email.text)
.Parameters.AddValueWith("#tech_rol",txt_tech_role.selectValue.tostring)
.ExecuteNonQuery()
End With
MessageBox.Show(msg, "INSERT", MessageBoxButtons.OK, MessageBoxIcon.Information)
Catch ex As Exception
MessageBox.Show(ex.Message.ToString, ". : : ERROR : : .", MessageBoxButtons.OK, MessageBoxIcon.Error)
Finally
If cn IsNot Nothing AndAlso cn.State <> ConnectionState.Closed Then
cn.Close()
cn = Nothing
End If
End Try
End Sub
Because I have a module that is separate from the main code , I'm not able to call the textboxes because they are separate from the main module ... any idea on how to do this ?? ... Dont be hard .. This is my 14 week working with VB.. :/
Add to the Insert function parameter for SqlParameters
Public Sub Insert(query As String, msg As String, params As SqlParameter())
Dim cn As New SqlConnection(cs)
Dim cmd As New SqlCommand
Try
cn.Open()
With cmd
.CommandType = CommandType.Text
.CommandText = query
.Connection = cn
If params IsNot Nothing AndAlso params.Count > 0 Then
.Parameters.AddRange(params)
End If
.ExecuteNonQuery()
End With
MessageBox.Show(msg,
"INSERT",
MessageBoxButtons.OK,
MessageBoxIcon.Information)
Catch ex As Exception
MessageBox.Show(ex.Message.ToString, ". : : ERROR : : .",
MessageBoxButtons.OK,
MessageBoxIcon.Error)
Finally
If cn IsNot Nothing AndAlso cn.State <> ConnectionState.Closed Then
cn.Close()
cn = Nothing
End If
End Try
End Sub
Then use it like this:
Dim query As String = "INSERT INTO Technician (tec_name, tec_email, rol_id) VALUES (#tech_name, #tech_email, #tech_role)"
Dim msg As String = "Technican Add Correct"
Dim params As SqlParameter() = {New SqlParameter("#tech_name",txt_tech_name.text),
New SqlParameter("#tech_email",txt_tech_email.text),
New SqlParameter("#tech_rol",txt_tech_role.selectValue.tostring)}
Procedures.Insert(query, msg, params)
Using array of SqlParameter give you a possibility for using same function with parameter type other then string
You can have it this way... it works for me.
String query = "INSERT INTO Technician(tec_name, tec_email, rol_id) VALUES(#tech_name, #tech_email, #tech_rolr)"
params = {"tech_name", "tech_email", "tech_rolr"}
values = {"" & txt_tech_name.text, "" & txt_tech_email.text, "" & txt_tech_role.selectValue.tostring()}
SaveUpdateDelete(query, params, values)
under module, you can put this
Public params() As String
Public values() As String
Public Sub SaveUpdateDelete(ByVal sql As String, ByVal parameters() As String, ByVal Values() As String)
If con.State = ConnectionState.Open Then
con.Close()
End If
con.Open()
command = New MySqlCommand(sql, con)
For i = 0 To parameters.Count - 1
command.Parameters.AddWithValue("#" & parameters(i).ToString, Values(i))
Next
command.CommandText = sql
command.ExecuteNonQuery()
con.Close()
End Sub
the method SaveUpdateDelete is applicable for adding, updating and deleting data.. your code will only differ in query... "insert, update, delete"
I have tried to insert or update from my vb.net form into MS-Access database.
The dataset updates but the access database wont. Below is my code.
Try
Dim addLocation As String = "Insert into Provider (StateCode, Provider)" _
& "values ('" & ComboBox1.Text & "', '" & TextBox2.Text & "')"
Dim sqlcommand As New OleDbCommand
conn.Open()
With sqlcommand
.CommandText = addLocation
.Connection = conn
.ExecuteNonQuery()
End With
MsgBox("One record added", MsgBoxStyle.Information)
refreshGrid()
Catch ex As Exception
MsgBox(ex.ToString)
End Try
Private Sub refreshGrid()
cnString = "PROVIDER = Microsoft.ace.oledb.12.0;data source =" & Application.StartupPath & "\HCHPClosedIn.accdb"
sqlQRY = "SELECT * FROM Provider"
conn = New OleDbConnection(cnString)
Try
conn.Open()
da = New OleDbDataAdapter(sqlQRY, conn)
Dim cb As OleDbCommandBuilder = New OleDbCommandBuilder(da)
da.Fill(ds, "Customers")
DataGridView1.DataSource = ds
DataGridView1.DataMember = "Customers"
End Try
End Sub
Its been a while but I think I recall Access is kinda picky with commit. Try this:
With sqlcommand
.CommandText = addLocation
.Connection = conn
.ExecuteNonQuery()
.transaction = trans
End With
Trans.Commit()
I have a next button.
theres no error i just want to simplify
Try
lblcat.Text = ds.Tables("evaluation").Rows(cat)("QuestionCategory")
txt1.Text = ds.Tables("evaluation").Rows(CurrentRow)("Question")
txt2.Text = ds.Tables("evaluation").Rows(CurrentRow + 1)("Question")
txt3.Text = ds.Tables("evaluation").Rows(CurrentRow + 2)("Question")
txt4.Text = ds.Tables("evaluation").Rows(CurrentRow + 3)("Question")
txt5.Text = ds.Tables("evaluation").Rows(CurrentRow + 4)("Question")
Catch ex As Exception
End Try
every click to the next button my category and questions change.
every click i want also to save in my database
Private Sub Save_commit()
Dim con As New OleDbConnection
Dim cmd As New OleDbCommand
Dim sSQL As String = String.Empty
Try
'get connection string declared in the Module1.vb and assing it to conn variable
con = New OleDbConnection(Get_Constring)
con.Open()
cmd.Connection = con
cmd.CommandType = CommandType.Text
'I just use the textbox tag property to idetify if the data is new or existing.
sSQL = "INSERT INTO evaluationresult ([Com])" & _
" VALUES (?)"
cmd.CommandText = sSQL
cmd.Parameters.AddWithValue("#FacultyID", txtresult.Text)
'cmd.Parameters.AddWithValue("#IDNumber", OleDbType.Numeric).Value
'cmd.Parameters.AddWithValue("#Com", OleDbType.Numeric).Value
' cmd.Parameters.AddWithValue("#Know", OleDbType.Numeric).Value
'cmd.Parameters.AddWithValue("#Teaching", OleDbType.Numeric).Value
'cmd.Parameters.Addwithvallue("#man", OleDbType.Numeric).Value()
'cmd.Parameters.AddWithValue("#ID", OleDbType.Numeric).Value
cmd.ExecuteNonQuery()
Catch ex As Exception
MsgBox(ErrorToString)
Finally
con.Close()
End Try
End Sub
please improve
Hi I'm completely lost on this piece of code (also very new) I am trying to create a session after the else statement. How do you create a session and for it to be read by another file ?
Dim conn As MySqlConnection
'connect to DB
conn = New MySqlConnection()
conn.ConnectionString = "server=localhost;Port=3306; user id=****; password=****; database=testtable"
'see if connection failed.
Try
conn.Open()
Catch myerror As MySqlException
MessageBox.Show("Error Connection to Database: " & myerror.Message)
End Try
'sql query
Dim myAdapter As New MySqlDataAdapter
Dim sqlquery = "SELECT * FROM members Where login='" & UsernameTextBox.Text & "' and passwd='" & PasswordTextBox.Text & "'"
Dim myCommand As New MySqlCommand()
myCommand.Connection = conn
myCommand.CommandText = sqlquery
'start query
myAdapter.SelectCommand = myCommand
Dim myData As MySqlDataReader
myData = myCommand.ExecuteReader()
'see if user exits.
If myData.HasRows = 0 Then
MessageBox.Show("Invalid Username/Password", "Login Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
Else
Dim login As String = System.Web.HttpContext.Current.Session("login")
System.Web.HttpContext.Current.Session("login") = UsernameTextBox.Text
Dim Form1 = New Form1
Form1.Show()
Me.Visible = False
End If
Thanks for any help
Session only exists in ASP.Net.
You should pass information in constructor parameters and/or properties of your form classes.