Implement a search engine in ASP.NET and VB.net from .sdf database

Question

I'm trying to implement a search engine in ASP.NET and VB.net. The search is from a .sdf database. I keep getting a:

System.NullReferenceException: Object reference not set to an instance of an object

The error occurs on the line

myDA.SelectCommand = cm

But I can't point out the source of error since my code looks clean. I will appreciate some Help

Private Sub searchButton_click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles searchButton.Click
    registration.Visible = True
    con.Open()
    cm.Connection = con
    cm.CommandText = "SELECT * FROM records WHERE phone = " & phoneTextBox.Text
    cm.ExecuteNonQuery()
    myDA.SelectCommand = cm
    myDA.Fill(myDataSet, "records")

    If myDataSet.Tables("records").Rows.Count = 0 Then
        TextBox1.Text = ""
        TextBox2.Text = ""
        TextBox3.Text = ""
        TextBox4.Text = ""
        TextBox5.Text = ""
        TextBox6.Text = ""
        Response.Write("Record not Found")
    Else
        TextBox1.Text = myDataSet.Tables("Records").Rows(0).Item("phone")
        TextBox2.Text = myDataSet.Tables("Records").Rows(0).Item("name")
        TextBox3.Text = myDataSet.Tables("Records").Rows(0).Item("id")
        TextBox4.Text = myDataSet.Tables("Records").Rows(0).Item("pin")
        TextBox5.Text = myDataSet.Tables("Records").Rows(0).Item("area")
        TextBox6.Text = myDataSet.Tables("Records").Rows(0).Item("subscription")
    End If
End Sub

Where is the variable `myDA` declared in your code? You're setting it to something but you're not declaring its data type beforehand — Nick.Mc, Nov 05 '15 at 22:50

score 0 · Answer 1 · answered Nov 02 '15 at 09:06

0

your error is here

          cm.CommandText = "SELECT * FROM records WHERE phone = " +& phoneTextBox.Text

phone numbers are string or varchar fields which means they have to be put in 'quotes'.since you havent the query isnt executing and returning you an empty result(0 rows). when you try access the first row i.e row[0] since there are no rows your are getting a nullrefrence exception

modify your code like this

     cm.CommandText = "SELECT * FROM records WHERE phone = '" +phoneTextBox.Text+"'"

answered Nov 02 '15 at 09:06

Sujit.Warrier

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i have modified and the error persists – Tunan Nov 02 '15 at 09:10
it says that this line is the source myDA.SelectCommand = cm – Tunan Nov 02 '15 at 09:11
ok either use executenonquery or dataadapter.fill method. dont use both. try commenting the cm.executenonquery() – Sujit.Warrier Nov 02 '15 at 09:21
it still get an error..could the problem be with my imports? – Tunan Nov 02 '15 at 09:35

Implement a search engine in ASP.NET and VB.net from .sdf database

1 Answers1