How to sumit a query from a different form window

05-12-2012, 05:12 PM

Anthei

Newcomer

Join Date: May 2012

Posts: 1

How to sumit a query from a different form window

I'm creating an inventory application. It has a combo box for rooms, and I'm trying to code the "Display" button. I got it to open up the database in a new window, but I'm trying to get it to come up and search the database with the cmbRooms.Text information and compare it to the room data in the records. I'm wondering if that's even possible? If so, am I able to do it from the Main Form, or do I have to modify the code in the Database form instead, or in addition to the Main Form's code?

Here's the Main Form's Display button code so far. When I run the application and select a room, and click "Display", it comes up with an error on this line:
Call frmDatabase.Show(record)
I've tried to get it to work, but I can't find an example or help on how to do it anywhere!

Code:

    Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click
        'displays the Database window with a search query of the specified room

        'Declarations
        Dim frmDatabase As New Database()
        Dim query As String
        query = "SELECT * FROM inventory WHERE room LIKE '%'" & cmbRooms.Text & "'%'"

            'If textbox for cmbRooms is occupied, and holds the value "All"
            'Then show the whole database
        If cmbRooms.Text = "All" Then
            frmDatabase.Show()
        ElseIf cmbRooms.Text > "0" Then
            'if textbox occupied, search database using query
            frmDatabase.Show(query)
        Else
            'if textbox empty, view error
            MessageBox.Show("Please select a room or type 'All' in the Room text field to view all entries.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1)
        End If

    End Sub

Here's the code for my database form:

Code:

Public Class Database

    Private Sub InventoryBindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles InventoryBindingNavigatorSaveItem.Click
        Me.Validate()
        Me.InventoryBindingSource.EndEdit()
        Me.TableAdapterManager.UpdateAll(Me.InventoryDataSet)

    End Sub

    Private Sub Database_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'TODO: This line of code loads data into the 'InventoryDataSet.Inventory' table. You can move, or remove it, as needed.
        Me.InventoryTableAdapter.Fill(Me.InventoryDataSet.Inventory)

    End Sub
End Class

EDIT: I realized only now that I put this in the wrong area, as this is .NET, not 6 like I thought it was. I apologize.

Last edited by Anthei; 05-12-2012 at 05:42 PM.

05-14-2012, 07:08 AM

DrPunk

Senior Contributor

* Expert *

Join Date: Apr 2003

Location: Never where I want to be

Posts: 1,278

Firstly, you can't pass random stuff to the Form's Show method so that's not the way to go.

What you should probably be doing is using the Form's Constructor to pass the relevant information to the Database form.

The big question is what to send to the Database form? The best answer to this question would depend on how you might want to extend this further, but a simple example would pass the SQL Query that the database form has to run. That way you could have many other uses for the database form and you just have to send it the query to run. Also, all the Database form has to do is run the query that it is given and display the results.

Firstly there's the constructor for the Database form. Constructors are the Sub New for a class. Forms are a bit different that other classes in that a Form's Sub New must have InitializeComponent called in it. If you don't have InitializeComponent in a Form's Sub New then the IDE will moan about an error and won't compile the project.

So, The Database Form's class now includes...

Code:

Public Class Database
    
    ' A private variable to store the query in
    private queryToRun as string

    Public Sub New(byval query as String)
        ' This call is required by the Windows Form Designer.
        InitializeComponent

        ' Save the query to run
        me.queryToRun = query
    End Sub

End Class

Then, in the Form's load event, you'll use the query to set up a Command to run and display.

Using the Database class that now has a constructor, the following line in your code won't work...

Code:

 Dim frmDatabase As New Database()

... because you can't create a database form without passing it a query to run (i.e. there is no Sub New without any parameters). That's a good thing because in the Database form we don't have to worry about whether a query has been passed or not. It must have been because the form couldn't have been created without one.

So, the code to use it would now look something like...

Code:

Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click
        'displays the Database window with a search query of the specified room

        'Declarations
        ' No New here now in the declaration of the form. It will be created later when the query is known 
        Dim frmDatabase As Database()

            'If textbox for cmbRooms is occupied, and holds the value "All"
            'Then show the whole database
        If cmbRooms.Text = "All" Then
            frmDatabase = New Database("SELECT * FROM inventory")
            frmDatabase.Show
        ElseIf cmbRooms.Text > "0" Then
            frmDatabase = New Database("SELECT * FROM inventory WHERE room LIKE '%'" & cmbRooms.Text & "'%'")
            frmDatabase.Show
        Else
            'if textbox empty, view error
            MessageBox.Show("Please select a room or type 'All' in the Room text field to view all entries.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1)
        End If

    End Sub

__________________
There are no computers in heaven!