validating combobox

[jhedonghae]

please kindly help me!!!
what i wanted is when i select items in the combobox and it is already in the database it will prompt that it is already in the database..tnx

Private Sub ComboBox3_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles ComboBox3.Validating
        If ComboBox3.Validating Then
            con = New OleDbConnection("Provider= Microsoft.ACE.oledb.12.0; Data Source=C:\Users\edenzam\Desktop\CBFMNHS Enrollment System\CBFMNHS Enrollment System\bin\Debug\Enrollment System.accdb")
            Dim ewaaa As String = "Select * from SchedulingTwos  where YearLevels = '" & ComboBox1.Text & "'"
            com = New OleDbCommand(ewaaa, con)
            con.Open()
            com.ExecuteNonQuery()
            rid = com.ExecuteReader
            rid.Read()
            If (rid.HasRows) Then
                ComboBox3.Text = rid(2)
                MsgBox("Section Already Exist", MsgBoxStyle.Critical, "Error")
                ComboBox3.SelectedIndex = -1
            End If
        End If
    End Sub

[jhedonghae]

i needed the answer badly..please help me

[poojavb]

What does ur combobox1 contains and what is in combobox3

Private Sub ComboBox3_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles ComboBox3.Validating
    If ComboBox3.Validating Then
    con = New OleDbConnection("Provider= Microsoft.ACE.oledb.12.0; Data Source=C:\Users\edenzam\Desktop\CBFMNHS Enrollment System\CBFMNHS Enrollment System\bin\Debug\Enrollment System.accdb")
    Dim ewaaa As String = "Select * from SchedulingTwos where YearLevels = '" & ComboBox1.Text & "'"
    com = New OleDbCommand(ewaaa, con)
    con.Open()
    rid = com.ExecuteReader
        if rid.Read=True then
                MsgBox("Section Already Exist", MsgBoxStyle.Critical, "Error")
                ComboBox3.SelectedIndex = -1
        End If
    End If
End Sub

[jhedonghae]

combobox1 contains the items First Year, Second Year, Third Year, Fourth Year and combobox3 contains sections 1 - 15

[jhedonghae]

and their is an error with this code "If ComboBox3.Validating Then"

[poojavb]

use the below select query

"Select * from SchedulingTwos where YearLevels = '" & ComboBox1.Text & "'" and Sections = '" & ComboBox3.Text & '""

if this condition is true then u will get the alert message that the section is already added

[jhedonghae]

this code generates an error com = New OleDbCommand(ewaaa, con) it says that ewaaa is not declared

[poojavb]

paste ur code again so that we can help u....if already fixed mark the thread as solved....
Remove the if condition of validating...see if com is declared....check the connections

[venus1]

this code generates an error com = New OleDbCommand(ewaaa, con) it says that ewaaa is not declared

[jhedonghae]

Private Sub ComboBox3_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles ComboBox3.Validating
        If ComboBox3.Text = "'" Then
            con = New OleDbConnection("Provider= Microsoft.ACE.oledb.12.0; Data Source=C:\Users\edenzam\Desktop\CBFMNHS Enrollment System\CBFMNHS Enrollment System\bin\Debug\Enrollment System.accdb")
            Dim ewaaa As String = "Select * from Schedulings where YearLevels = '" & ComboBox3.Text & "' And Sections = '" & ComboBox1.Text & "' "
            com = New OleDbCommand(ewaaa, con)
            con.Open()
            rid = com.ExecuteReader
            rid.Read()
            If (rid.HasRows) Then
                ComboBox3.Text = rid(2)
                MsgBox("Section Already Exist", MsgBoxStyle.Critical, "Error")
                ComboBox3.SelectedIndex = -1
            End If
        End If
    End Sub

[jhedonghae]

i think the problem is in this part "If ComboBox3.Text = "'" Then" i just don't know how to manipulate combobox when the event is validating...please help me

[poojavb]

Remove that if (If ComboBox3.Text = "'") condition y u need it???

and u have written double quotes then single quote and then double quotes in the if condition for combobox text....y u need that??? remove the single quote and keep it just If ComboBox3.Text = "" Then....i would recommend to remove that condition

anyways if this is the condition it wont enter the if loop anytime...

[jhedonghae]

ok i'll remove it and update if tis works..thanks

[jhedonghae]

i change my codes to this:

 Private Sub ComboBox3_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles ComboBox3.Validating
        con = New OleDbConnection("Provider= Microsoft.ACE.oledb.12.0; Data Source=C:\Users\edenzam\Desktop\CBFMNHS Enrollment System\CBFMNHS Enrollment System\bin\Debug\Enrollment System.accdb")
        Dim ewaaa As String = "Select * from Schedulings where YearLevels = '" & ComboBox3.Text & "' And Sections = '" & ComboBox1.Text & "' "
        com = New OleDbCommand(ewaaa, con)
        con.Open()
        rid = com.ExecuteReader
        rid.Read()
        If (rid.HasRows = True) Then
            ComboBox3.Text = rid(2)
            MsgBox("Section Already Exist", MsgBoxStyle.Critical, "Error")
            ComboBox3.SelectedIndex = -1
        Else
            ' do nothing
        End If
    End Sub

but still it is not working

[Mitja Bonca]

1st, why use use Validating event? Why not SelectedIndexChnaged (of comboBox(es))?
2nd, change comboBoxX.Text with comboBoxX.SelectedItem.tostring()
3rd, remove "if(rid.HasRows)" out of the code, change it with "if(rid.Read())" statement
and last,:
You cannot use comboBox3.Text, this will do nothing. What you can do, is to ADD a new Item to this comboBox. And then select it (if you want to show it on top (in "textBox" of comboBox area).
So change ComboBox3.Text = rid(2) to: ComboBox3.Items.Add(rid(2).ToString())

--
Hope it helps,
bye

[jhedonghae]

@Mitja this is my new code that i based from what you said i hope i did it the way you wanted because it still didn't work

Private Sub ComboBox3_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox3.SelectedIndexChanged
con = New OleDbConnection("Provider= Microsoft.ACE.oledb.12.0; Data Source=C:\Users\edenzam\Desktop\CBFMNHS Enrollment System\CBFMNHS Enrollment System\bin\Debug\Enrollment System.accdb")
Dim ewaaa As String = "Select * from Schedulings where YearLevels = '" & ComboBox3.Text & "' And Sections = '" & ComboBox1.Text & "' "
com = New OleDbCommand(ewaaa, con)
con.Open()
rid = com.ExecuteReader
rid.Read()
If (rid.Read()) Then
ComboBox3.Items.Add(rid(2).ToString())
MsgBox("Section Already Exist", MsgBoxStyle.Critical, "Error")
ComboBox3.SelectedIndex = -1
Else
' do nothing
End If
End Sub

and by the way where do i add this code? 2nd, change comboBoxX.Text with comboBoxX.SelectedItem.tostring()
tnx

[Mitja Bonca]

Ok, I did renovate your code, and it you have data inside your table (and it connection string is the right one), is must work:

Private Sub ComboBox3_SelectedIndexChanged(sender As System.Object, e As System.EventArgs)
    con = New OleDbConnection("Provider= Microsoft.ACE.oledb.12.0; Data Source=C:\Users\edenzam\Desktop\CBFMNHS Enrollment System\CBFMNHS Enrollment System\bin\Debug\Enrollment System.accdb")
    Dim ewaaa As String = "SELECT * FROM Schedulings WHERE YearLevels = '" & ComboBox3.SelectedItem.ToString() & "' AND Sections = '" & ComboBox1.SelectedItem.ToString() & "'"
    com = New OleDbCommand(ewaaa, con)
    con.Open()
    rid = com.ExecuteReader()
    If rid.Read() Then
        Dim text As String = rid(2).ToString()
        ComboBox3.Items.Add(text)
        '2 means 3rd column! do you have 3 columns inside table?
        'show this on top:
        ComboBox1.Text = text
            'Interaction.MsgBox("Section Already Exist", MsgBoxStyle.Critical, "Error");               
        ComboBox3.SelectedIndex = -1
            ' do nothing
    Else
    End If
End Sub

[jhedonghae]

yes i have three columns...i'm sorry but it still didn't work

[Mitja Bonca]

Put a break point before this line of code:
Dim text As String = rid(2).ToString()

and you will see by putting a mouse cursor over "text" variable if there is any text iside.
If it is , it code should put text into comboBox, else its something wrong with query statement.

[jhedonghae]

what does that mean..i'm confused..sorry

[jhedonghae]

it works tnx but when i click the message box the attach image that shows the problem occurs

[poojavb]

U can use Debug.Print("text: "+ text) to check the value...if u dont know how to use debugger

it will show the value of the word declared as a variable but it should be string else convert it to String...

Try this below code...

  Private Sub ComboBox3_SelectedIndexChanged(sender As System.Object, e As System.EventArgs)

con = New OleDbConnection("Provider= Microsoft.ACE.oledb.12.0; Data Source=C:\Users\edenzam\Desktop\CBFMNHS Enrollment System\CBFMNHS Enrollment System\bin\Debug\Enrollment System.accdb")

Dim ewaaa As String = "SELECT * FROM Schedulings WHERE YearLevels = '" & ComboBox3.SelectedItem.ToString() & "' AND Sections = '" & ComboBox1.SelectedItem.ToString() & "'"
com = New OleDbCommand(ewaaa, con)
con.Open()
rid = com.ExecuteReader()
    If rid.Read = True Then
       MsgBox("Section Already Exist", MsgBoxStyle.Critical, "Error");
       else
       MsgBox("Section does not Exist", MsgBoxStyle.Critical, "Error");
    End If
End Sub

[poojavb]

instead of & use + sign.....if still it does not work then try to convert SelectedItem.ToString to Text....hope it works for u...

[jhedonghae]

tnx