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How to correct this error and why it comes.

Posted on 2012-04-06
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Last Modified: 2012-04-24
I have a windows form and coding in vb.net.
A textbox txttid is there.
When i enter any numbers if fetches the data based on that tid and returns the resultset.
If no data is available then it gives invalid TID as message
empties the txttid.But simultenously raises the following exception

The Query is :

s = "select isnull(sname,''),isnull(gender,''),isnull(slandline,''),isnull(smobile,''),isnull(sstate,'') from mststudents where id=" & Convert.ToInt32(TXTTID.Text.Trim()) & " and sname is  null"
            da = New SqlDataAdapter(s, con)
            dt = New DataTable
            da.Fill(dt)
            If dt.Rows.Count = 0 Then
                MessageBox.Show("Invalid TID")
                TXTTID.Text = ""
                TXTTID.Focus()
                txtuin.Text = ""
                txtuin.Enabled = False

            Else
                txtsname.Text = dt.Rows(0)(0).ToString()
            end if

Exception is System.Format  Exception. Input string was not in correct format.
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Question by:searchsanjaysharma
3 Comments
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 37815630
The reason you would get that error is if your call to Integer.ConvertToInt32 was passed a non-numeric string. Check that the data you are passing is correct--even a blank or empty string will raise this exception.

See #2 here:  http://www.experts-exchange.com/Programming/Languages/.NET/A_5389-5-Common-Exceptions-in-NET-and-How-to-Resolve-Them.html
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LVL 44

Accepted Solution

by:
Arthur_Wood earned 1000 total points
ID: 37815726
try this approach:

Dim ID as String
If  Int32.TryConvert(TXTTID.Text.Trim(), ID) Then

s = "select isnull(sname,''),isnull(gender,''),isnull(slandline,''),isnull(smobile,''),isnull(sstate,'') from mststudents where id=" & ID & " and sname is  null"
            da = New SqlDataAdapter(s, con)
            dt = New DataTable
            da.Fill(dt)
            If dt.Rows.Count = 0 Then
                MessageBox.Show("Invalid TID")
                TXTTID.Text = ""
                TXTTID.Focus()
                txtuin.Text = ""
                txtuin.Enabled = False

            Else
                txtsname.Text = dt.Rows(0)(0).ToString()
            end if
else
     MessageBox.Show(TXTTID.Text & " is not a valid integer)
end if

this will catch an Invalid value in the Text Box.

AW
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Author Closing Comment

by:searchsanjaysharma
ID: 37885169
ok
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