How to Change Startup Form

2017-06-26

Question

_{Monday, June 26, 2017 4:37 PM}

I want change Startup Form. If A = 1 then Form2.show Else Form1.show. How to write this code in Module then how to set Startup Form. Please help my problem.

dopenoinam

All replies (9)

_{Tuesday, June 27, 2017 7:00 AM ✅Answered}

Hi Dopen,

Please right-click project choose PropertiesApplication Tabclick View Application Events, like this:

Then you will see ApplicationEvents.vb file in your project, the I suggest you to create new Module to connection MySQL, like this:

Module Module1
    Public Function loaddate(ColumnName As String) As Integer
        Dim ConnectionString As String = "Server=;Database=test;Uid=root;Pwd=;"
        Dim sql As String = "select ID from test2 where ColumnName=@ColumnName "
        Dim result As Integer

        Using con As New MySqlConnection(ConnectionString)

            Using cmd As New MySqlCommand(sql, con)
                con.Open()
                cmd.Parameters.AddWithValue("@ColumnName", ColumnName)
                cmd.CommandType = CommandType.Text
                Dim reader = cmd.ExecuteReader
                If reader.HasRows Then
                    reader.Read()
                    result = reader.GetInt32(0)
                End If
            End Using
        End Using
        Return result
    End Function
End Module

then add this method in the ApplicationEvents.vb

 Private Sub MyApplication_Startup(ByVal sender As Object, ByVal e As Microsoft.VisualBasic.ApplicationServices.StartupEventArgs) Handles Me.Startup
            'Select the form of your choice
            Dim a As String = "A"
            If IsDBNull(loaddate(a)) Then
                My.Application.MainForm = Form1
            Else
                My.Application.MainForm = Form2
            End If

        End Sub

Best Regards,

Cherry

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_{Tuesday, June 27, 2017 7:44 AM ✅Answered}

Cherry,

Maybe better to show it in VB instead of using C# and then convert only the code to VB.

Your reply is direct visible to be done with that because the project properties screen is not VB.

If you want (have) to do more than simple administrative help here, than try at least to learn VB.

By the way, that view application events was helpful, it was the first time I became aware of it.

Success
Cor

_{Tuesday, June 27, 2017 9:32 AM ✅Answered}

In regards to you working with MySql, what I've shown works with MySql by changing the data provider as I indicated in the first sentence of my reply.

If you look at Cherry's reply, the first code block is my code except for they used a code module and changed the data provider. So this shows what I indicated works BUT would not recommend using a code module but instead as I show a class. The only time to use a code module is for language extension methods which is the same as a static class in C# so stick with a class as I've shown.

Please remember to mark the replies as answers if they help and unmark them if they provide no help, this will help others who are looking for solutions to the same or similar problem. Contact via my Twitter (Karen Payne) or Facebook (Karen Payne) via my MSDN profile but will not answer coding question on either.
VB Forums - moderator

_{Monday, June 26, 2017 4:59 PM}

In the solution explorer, double click My Project.
On the Application tab, click the View Application Events button.
In the code file which appears (ApplicationEvents.vb), place the cursor at the end of the line "Partial Friend Class MyApplication"
Using the right-most dropdown at the top of the code editor window, select "OnCreateMainForm"
In the code window which appears (Application.Designer.vb) modify "Sub OnCreateMainForm" and enter your conditional logic for specifying which form should be used as the main form.

'
' <auto-generated>
'     This code was generated by a tool.
'     Runtime Version:4.0.30319.42000
'
'     Changes to this file may cause incorrect behavior and will be lost if
'     the code is regenerated.
' </auto-generated>
'

Option Strict On
Option Explicit On


Namespace My
    
    'NOTE: This file is auto-generated; do not modify it directly.  To make changes,
    ' or if you encounter build errors in this file, go to the Project Designer
    ' (go to Project Properties or double-click the My Project node in
    ' Solution Explorer), and make changes on the Application tab.
    '
    Partial Friend Class MyApplication
        
        <Global.System.Diagnostics.DebuggerStepThroughAttribute()>  _
        Public Sub New()
            MyBase.New(Global.Microsoft.VisualBasic.ApplicationServices.AuthenticationMode.Windows)
            Me.IsSingleInstance = false
            Me.EnableVisualStyles = true
            Me.SaveMySettingsOnExit = true
            Me.ShutDownStyle = Global.Microsoft.VisualBasic.ApplicationServices.ShutdownMode.AfterMainFormCloses
        End Sub
        
        <Global.System.Diagnostics.DebuggerStepThroughAttribute()>  _
        Protected Overrides Sub OnCreateMainForm()
            Me.MainForm = Global.WindowsApplication34.Form1
        End Sub
    End Class
End Namespace

Note the caveats in the comments which indicate that certain actions could reset this code file - primarily, avoid using the Application tab of My Project to make any changes to the startup object.

Reed Kimble - "When you do things right, people won't be sure you've done anything at all"

_{Monday, June 26, 2017 5:31 PM}

I would not do it in the way you tell it, however this is what you ask

Put this code in your module

Module Module1
    Sub main()
        Application.Run(New Form2)
        Application.Run(New Form1)
    End Sub
End Module

Now put in form 2 your question, you don't tell what is A so making sample code is difficult

And chance the startup object and set application framework off

I would not use 2 forms but simply use a panel that I show if the question is done instead of that other panel on which is the question.

But this is your question answered in my opinion.

Success
Cor

_{Monday, June 26, 2017 6:03 PM}

A means If IsDBNull(Dr(0)) then, Form1.show Else Form2.show

dopenoinam

_{Monday, June 26, 2017 6:10 PM}

Show then your module, because Dr is probably a DataReader although ti can also be a DataRow

However, normally you should be able to do that yourself if you use the by my supplied code.

Success
Cor

_{Monday, June 26, 2017 10:36 PM}

Here is a very simple example which reads from a MS-Access table (could also be SQL-Server or perhaps MySql, does not matter as they all support the objects used below), if a person by the last name of Payne is located show Form2, if not show Form1. Since there is a person with the last name of Payne (yep, me) Form2 is shown.

Steps

1.
2. Project properties, Application tab. 3. Click View Application events button. 4. Click the drop down at the top of the editor (see image below and select MyApplication Events 5. Use code such as shown below to open a database, query the table, return result and use the logic from the DataReader results to show the proper form. Yes it works as I wrote and tested it :-)

So I used integers, you are using letters, same logic applies but with letters you may need to do a case insensitive compare.

Imports Microsoft.VisualBasic.ApplicationServices
Imports System.Data.OleDb
Namespace My
    Partial Friend Class MyApplication
        Private Sub MyApplication_Startup(sender As Object, e As StartupEventArgs) Handles Me.Startup
            Dim ops As New DataOperations
            If ops.Load = -1 Then
                Application.MainForm = Form1
            Else
                Application.MainForm = Form2
            End If
        End Sub
    End Class
    Public Class DataOperations
        Private Builder As New OleDbConnectionStringBuilder With
        {
            .Provider = "Microsoft.ACE.OLEDB.12.0",
            .DataSource = IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Database3.accdb")
        }
        Public Function Load() As Integer
            Dim result As Integer = -1
            Using cn As New OleDbConnection With {.ConnectionString = Builder.ConnectionString}
                Using cmd As New OleDbCommand With {.Connection = cn}
                    cmd.CommandText = "SELECT id From Person WHERE LastName=@LastName;"
                    cmd.Parameters.AddWithValue("@LastName", "Payne")
                    cn.Open()
                    Dim reader = cmd.ExecuteReader
                    If reader.HasRows Then
                        reader.Read()
                        result = reader.GetInt32(0)
                    End If
                End Using
            End Using
            Return result
        End Function
    End Class
End Namespace

_{Tuesday, June 27, 2017 5:22 AM}

Thanks Ma'm, My database is MySQL not MS-Access. I've not idea for this :

 Public Class DataOperations
        Private Builder As New OleDbConnectionStringBuilder With
        {
            .Provider = "Microsoft.ACE.OLEDB.12.0",
            .DataSource = IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Database3.accdb")
        }
        Public Function Load() As Integer
            Dim result As Integer = -1
            Using cn As New OleDbConnection With {.ConnectionString = Builder.ConnectionString}
                Using cmd As New OleDbCommand With {.Connection = cn}
                    cmd.CommandText = "SELECT id From Person WHERE LastName=@LastName;"
                    cmd.Parameters.AddWithValue("@LastName", "Payne")
                    cn.Open()
                    Dim reader = cmd.ExecuteReader
                    If reader.HasRows Then
                        reader.Read()
                        result = reader.GetInt32(0)
                    End If
                End Using
            End Using
            Return result
        End Function
    End Class

dopenoinam

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