VB.NET

Datagrid Problem!!!!!!!

Please support our VB.NET advertiser: Intel Parallel Studio Home

•

Join Date: Jun 2007

Posts: 23

Reputation: Kshiteesh is an unknown quantity at this point

Solved Threads: 0

Kshiteesh

Offline

Newbie Poster

Datagrid Problem!!!!!!!

Aug 9th, 2007

I have inserted searching through passing parameter likewise. In search form there is only one textbox to pass the value. But there are three field names which are associated with that text box.

For example: I have searched by passing phone number
But there three field name tel1, tel2 and tel3 which which are called when the phone number is passed. my code is as follows. my frontend is vb.net and my backend is ms access.

 Help with Code Tags 
 vb.net Syntax (Toggle Plain Text) 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[inlinecode]
 
        Db1DataSet1.Clear()
        Dim conStr As String = "Provider=Microsoft.JET.OLEDB.4.0;data source=K:\Database\db1.mdb"
        Dim con As OleDb.OleDbConnection = New OleDb.OleDbConnection(conStr)
        Dim S As String
        Dim datagrid1 As New DataGrid
 
        Dim tmp As New ADODB.Recordset
        tmp.Open("add1", conStr, ADODB.CursorTypeEnum.adOpenDynamic, ADODB.LockTypeEnum.adLockOptimistic)
 
        If TextBox1.Text = tmp.Fields("tel1").Value Then
            S = "select * from add1 where tel1='" & TextBox1.Text & "'"
        ElseIf TextBox1.Text = tmp.Fields("tel2").Value Then
            S = "select * from add1 where tel2='" & TextBox1.Text & "'"
        ElseIf TextBox1.Text = tmp.Fields("tel3").Value Then
            S = "Select * from add1 where tel3='" & TextBox1.Text & "'"
 
        ElseIf Not (tmp.EOF = True And tmp.BOF = True) Then : MsgBox("no record found")
        End If
        Dim da As OleDb.OleDbDataAdapter = New OleDb.OleDbDataAdapter(S, con)
        da.Fill(Db1DataSet1, "add1")
        datagrid1.DataSource = Db1DataSet1.DefaultViewManager
[/inlinecode]
    End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[inlinecode]
        
        Db1DataSet1.Clear()
        Dim conStr As String = "Provider=Microsoft.JET.OLEDB.4.0;data source=K:\Database\db1.mdb"
        Dim con As OleDb.OleDbConnection = New OleDb.OleDbConnection(conStr)
        Dim S As String
        Dim datagrid1 As New DataGrid

        Dim tmp As New ADODB.Recordset
        tmp.Open("add1", conStr, ADODB.CursorTypeEnum.adOpenDynamic, ADODB.LockTypeEnum.adLockOptimistic)

        If TextBox1.Text = tmp.Fields("tel1").Value Then
            S = "select * from add1 where tel1='" & TextBox1.Text & "'"
        ElseIf TextBox1.Text = tmp.Fields("tel2").Value Then
            S = "select * from add1 where tel2='" & TextBox1.Text & "'"
        ElseIf TextBox1.Text = tmp.Fields("tel3").Value Then
            S = "Select * from add1 where tel3='" & TextBox1.Text & "'"

        ElseIf Not (tmp.EOF = True And tmp.BOF = True) Then : MsgBox("no record found")
        End If
        Dim da As OleDb.OleDbDataAdapter = New OleDb.OleDbDataAdapter(S, con)
        da.Fill(Db1DataSet1, "add1")
        datagrid1.DataSource = Db1DataSet1.DefaultViewManager
[/inlinecode]
    End Sub

In this snippet I have faced one problem. It shows one build error at

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
OleDb.OleDbDataAdapter(S, con)
OleDb.OleDbDataAdapter(S, con)

which says

Help with Code Tags

VB.NET Syntax (Toggle Plain Text)

Variable 'S' is used before it has been assigned a value. A null reference exception could result at runtime.

And when I run this program it executes until I pass the values present in the field , but when i pass the values not present in the fields then the msg box is shown as mentioned the program...but the problem persists when I click the ok button of msg box or try to stop debugging.
It shows the error at

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
 da.Fill(Db1DataSet1, "add1")
 da.Fill(Db1DataSet1, "add1")

which shows

Help with Code Tags

VB.NET Syntax (Toggle Plain Text)

OledbException was unhandled

showing

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
Command text was not set for the command object.
Command text was not set for the command object.

error.

I m a beginner of VB.net. so please help me what type of error is this and how can I solve this problem. please provide me with appropriate code to resolve the problem.

Anticipating the help.

Regards

Kshiteesh

•

Join Date: Nov 2006

Posts: 848

Reputation: QVeen72 is on a distinguished road

Solved Threads: 120

QVeen72

Offline

Practically a Posting Shark

Re: Datagrid Problem!!!!!!!

Aug 9th, 2007

Hi Kshiteesh,

few points what i have noted here...:

1. Before Creating the DataAdapter, u are not checking if "S" is blank or not.. the error which u have may be the same..
or else in ur If condition if nothing found, then exit sub..

2. Use a new Dataset. Check this:

Help with Code Tags

(Toggle Plain Text)

Dim ds AsNew DataSet
da.Fill(ds, "add1")
DataGrid1.DataSource = ds.DefaultViewManager

REgards
Veena

Last edited by QVeen72; Aug 9th, 2007 at 7:25 am.

•

Join Date: Jun 2007

Posts: 82

Reputation: preetham.saroja is an unknown quantity at this point

Solved Threads: 1

preetham.saroja preetham.saroja is offline

Offline

Junior Poster in Training

Re: Datagrid Problem!!!!!!!

Aug 10th, 2007

always make sure,u declare the
str,connectionstring,sqlcommand,sqldataadapter in this order..
Even if u try to access adapter b4 sqlcommand-then u get the errors(which u have got)...so,make sure first they are declared& then there objects are accesed....