Invalid attempt to read when no data is present.

[Helixpoint]

Dim dr1 As SqlDataReader = MachCodeListID.GetSingleMachCode(thecodesID)

' Read first row from database

dr1.Read()

If IsDBNull(dr1("CATNUM")) Then '**************** This is where I am getting
the error??????

thecatnum = 0

Else

thecatnum = dr1("CATNUM")

End If


--

______________________
David Fetrow
HelixPoint LLC.
[url]http://www.helixpoint.com[/url]
[email]davef@helixpoint.com[/email]

Interested in Affordable Email Marketing?
Check out the HelixMailer at [url]http://www.helixpoint.com/helixmailer.asp[/url]
If you are interested in becoming a Reseller of HelixPoint products, contact
[email]davef@helixpoint.com[/email]
______________________

[Marina]

Looks like there were no rows returned. dr1.Read returned false.

"Helixpoint" <dave@helixpoint.com> wrote in message
news:OyEoEjBPDHA.2228@tk2msftngp13.phx.gbl...

> Dim dr1 As SqlDataReader = MachCodeListID.GetSingleMachCode(thecodesID)
>
> ' Read first row from database
>
> dr1.Read()
>
> If IsDBNull(dr1("CATNUM")) Then '**************** This is where I am

getting

> the error??????
>
> thecatnum = 0
>
> Else
>
> thecatnum = dr1("CATNUM")
>
> End If
>
>
> --
>
> ______________________
> David Fetrow
> HelixPoint LLC.
> [url]http://www.helixpoint.com[/url]
> [email]davef@helixpoint.com[/email]
>
> Interested in Affordable Email Marketing?
> Check out the HelixMailer at [url]http://www.helixpoint.com/helixmailer.asp[/url]
> If you are interested in becoming a Reseller of HelixPoint products,

contact

> [email]davef@helixpoint.com[/email]
> ______________________
>
>

[Helixpoint]

Not to be a jerk, but I figured that out.


"Marina" <zlatkinam@nospam.hotmail.com> wrote in message
news:useiulBPDHA.2284@TK2MSFTNGP11.phx.gbl...

> Looks like there were no rows returned. dr1.Read returned false.
>
> "Helixpoint" <dave@helixpoint.com> wrote in message
> news:OyEoEjBPDHA.2228@tk2msftngp13.phx.gbl...

> > Dim dr1 As SqlDataReader = MachCodeListID.GetSingleMachCode(thecodesID)
> >
> > ' Read first row from database
> >
> > dr1.Read()
> >
> > If IsDBNull(dr1("CATNUM")) Then '**************** This is where I am

> getting

> > the error??????
> >
> > thecatnum = 0
> >
> > Else
> >
> > thecatnum = dr1("CATNUM")
> >
> > End If
> >
> >
> > --
> >
> > ______________________
> > David Fetrow
> > HelixPoint LLC.
> > [url]http://www.helixpoint.com[/url]
> > [email]davef@helixpoint.com[/email]
> >
> > Interested in Affordable Email Marketing?
> > Check out the HelixMailer at [url]http://www.helixpoint.com/helixmailer.asp[/url]
> > If you are interested in becoming a Reseller of HelixPoint products,

> contact

> > [email]davef@helixpoint.com[/email]
> > ______________________
> >
> >

>
>

[Marina]

If you figured out that no rows were returned, then what's the problem?

"Helixpoint" <dave@helixpoint.com> wrote in message
news:OT6UkqBPDHA.2788@TK2MSFTNGP10.phx.gbl...

> Not to be a jerk, but I figured that out.
>
>
> "Marina" <zlatkinam@nospam.hotmail.com> wrote in message
> news:useiulBPDHA.2284@TK2MSFTNGP11.phx.gbl...

> > Looks like there were no rows returned. dr1.Read returned false.
> >
> > "Helixpoint" <dave@helixpoint.com> wrote in message
> > news:OyEoEjBPDHA.2228@tk2msftngp13.phx.gbl...

> > > Dim dr1 As SqlDataReader =

MachCodeListID.GetSingleMachCode(thecodesID)

> > >
> > > ' Read first row from database
> > >
> > > dr1.Read()
> > >
> > > If IsDBNull(dr1("CATNUM")) Then '**************** This is where I am

> > getting

> > > the error??????
> > >
> > > thecatnum = 0
> > >
> > > Else
> > >
> > > thecatnum = dr1("CATNUM")
> > >
> > > End If
> > >
> > >
> > > --
> > >
> > > ______________________
> > > David Fetrow
> > > HelixPoint LLC.
> > > [url]http://www.helixpoint.com[/url]
> > > [email]davef@helixpoint.com[/email]
> > >
> > > Interested in Affordable Email Marketing?
> > > Check out the HelixMailer at [url]http://www.helixpoint.com/helixmailer.asp[/url]
> > > If you are interested in becoming a Reseller of HelixPoint products,

> > contact

> > > [email]davef@helixpoint.com[/email]
> > > ______________________
> > >
> > >

> >
> >

>
>

[Helixpoint]

I get an error when it checks for NULL???



"Marina" <zlatkinam@nospam.hotmail.com> wrote in message
news:unyL3sBPDHA.2228@tk2msftngp13.phx.gbl...

> If you figured out that no rows were returned, then what's the problem?
>
> "Helixpoint" <dave@helixpoint.com> wrote in message
> news:OT6UkqBPDHA.2788@TK2MSFTNGP10.phx.gbl...

> > Not to be a jerk, but I figured that out.
> >
> >
> > "Marina" <zlatkinam@nospam.hotmail.com> wrote in message
> > news:useiulBPDHA.2284@TK2MSFTNGP11.phx.gbl...

> > > Looks like there were no rows returned. dr1.Read returned false.
> > >
> > > "Helixpoint" <dave@helixpoint.com> wrote in message
> > > news:OyEoEjBPDHA.2228@tk2msftngp13.phx.gbl...
> > > > Dim dr1 As SqlDataReader =

> MachCodeListID.GetSingleMachCode(thecodesID)

> > > >
> > > > ' Read first row from database
> > > >
> > > > dr1.Read()
> > > >
> > > > If IsDBNull(dr1("CATNUM")) Then '**************** This is where I am
> > > getting
> > > > the error??????
> > > >
> > > > thecatnum = 0
> > > >
> > > > Else
> > > >
> > > > thecatnum = dr1("CATNUM")
> > > >
> > > > End If
> > > >
> > > >
> > > > --
> > > >
> > > > ______________________
> > > > David Fetrow
> > > > HelixPoint LLC.
> > > > [url]http://www.helixpoint.com[/url]
> > > > [email]davef@helixpoint.com[/email]
> > > >
> > > > Interested in Affordable Email Marketing?
> > > > Check out the HelixMailer at

[url]http://www.helixpoint.com/helixmailer.asp[/url]

> > > > If you are interested in becoming a Reseller of HelixPoint products,
> > > contact
> > > > [email]davef@helixpoint.com[/email]
> > > > ______________________
> > > >
> > > >
> > >
> > >

> >
> >

>
>

[Marina]

If there was no row returned, there is now way to check if a column in that
row is null - because there is no row in the first place!!!

"Helixpoint" <dave@helixpoint.com> wrote in message
news:%23zB3lvBPDHA.3836@tk2msftngp13.phx.gbl...

> I get an error when it checks for NULL???
>
>
>
> "Marina" <zlatkinam@nospam.hotmail.com> wrote in message
> news:unyL3sBPDHA.2228@tk2msftngp13.phx.gbl...

> > If you figured out that no rows were returned, then what's the problem?
> >
> > "Helixpoint" <dave@helixpoint.com> wrote in message
> > news:OT6UkqBPDHA.2788@TK2MSFTNGP10.phx.gbl...

> > > Not to be a jerk, but I figured that out.
> > >
> > >
> > > "Marina" <zlatkinam@nospam.hotmail.com> wrote in message
> > > news:useiulBPDHA.2284@TK2MSFTNGP11.phx.gbl...
> > > > Looks like there were no rows returned. dr1.Read returned false.
> > > >
> > > > "Helixpoint" <dave@helixpoint.com> wrote in message
> > > > news:OyEoEjBPDHA.2228@tk2msftngp13.phx.gbl...
> > > > > Dim dr1 As SqlDataReader =

> > MachCodeListID.GetSingleMachCode(thecodesID)

> > > > >
> > > > > ' Read first row from database
> > > > >
> > > > > dr1.Read()
> > > > >
> > > > > If IsDBNull(dr1("CATNUM")) Then '**************** This is where I

am

> > > > getting
> > > > > the error??????
> > > > >
> > > > > thecatnum = 0
> > > > >
> > > > > Else
> > > > >
> > > > > thecatnum = dr1("CATNUM")
> > > > >
> > > > > End If
> > > > >
> > > > >
> > > > > --
> > > > >
> > > > > ______________________
> > > > > David Fetrow
> > > > > HelixPoint LLC.
> > > > > [url]http://www.helixpoint.com[/url]
> > > > > [email]davef@helixpoint.com[/email]
> > > > >
> > > > > Interested in Affordable Email Marketing?
> > > > > Check out the HelixMailer at

> [url]http://www.helixpoint.com/helixmailer.asp[/url]

> > > > > If you are interested in becoming a Reseller of HelixPoint

products,

> > > > contact
> > > > > [email]davef@helixpoint.com[/email]
> > > > > ______________________
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >

> >
> >

>
>

[Marina]

There is no point to doing that. dr1.Read returned false - hence no rows.
Neither of these things will work. The structure needs to be

If dr1.Read() Then

If IsDbNull(dr1("Catnum") Then
.....
End If

End If
<daphish@msn.com> wrote in message
news:h0kmfv4iodtvt10qe8n4tracbsjl42f7ao@4ax.com...

> There is a difference between dbnull and the object being null. You
> also need to check if the object doesn't exists as well
>
> if not dr1("Catnum") is vbnullstring orelse isdbnull(dr1("catnum")
> then
>
>
> -dwayne
>
>
> On Thu, 26 Jun 2003 15:47:53 -0400, "Helixpoint" <dave@helixpoint.com>
> wrote:
>

> >I get an error when it checks for NULL???
> >
> >
> >
> >"Marina" <zlatkinam@nospam.hotmail.com> wrote in message
> >news:unyL3sBPDHA.2228@tk2msftngp13.phx.gbl...

> >> If you figured out that no rows were returned, then what's the problem?
> >>
> >> "Helixpoint" <dave@helixpoint.com> wrote in message
> >> news:OT6UkqBPDHA.2788@TK2MSFTNGP10.phx.gbl...
> >> > Not to be a jerk, but I figured that out.
> >> >
> >> >
> >> > "Marina" <zlatkinam@nospam.hotmail.com> wrote in message
> >> > news:useiulBPDHA.2284@TK2MSFTNGP11.phx.gbl...
> >> > > Looks like there were no rows returned. dr1.Read returned false.
> >> > >
> >> > > "Helixpoint" <dave@helixpoint.com> wrote in message
> >> > > news:OyEoEjBPDHA.2228@tk2msftngp13.phx.gbl...
> >> > > > Dim dr1 As SqlDataReader =
> >> MachCodeListID.GetSingleMachCode(thecodesID)
> >> > > >
> >> > > > ' Read first row from database
> >> > > >
> >> > > > dr1.Read()
> >> > > >
> >> > > > If IsDBNull(dr1("CATNUM")) Then '**************** This is where I

am

> >> > > getting
> >> > > > the error??????
> >> > > >
> >> > > > thecatnum = 0
> >> > > >
> >> > > > Else
> >> > > >
> >> > > > thecatnum = dr1("CATNUM")
> >> > > >
> >> > > > End If
> >> > > >
> >> > > >
> >> > > > --
> >> > > >
> >> > > > ______________________
> >> > > > David Fetrow
> >> > > > HelixPoint LLC.
> >> > > > [url]http://www.helixpoint.com[/url]
> >> > > > [email]davef@helixpoint.com[/email]
> >> > > >
> >> > > > Interested in Affordable Email Marketing?
> >> > > > Check out the HelixMailer at

> >[url]http://www.helixpoint.com/helixmailer.asp[/url]

> >> > > > If you are interested in becoming a Reseller of HelixPoint

products,

> >> > > contact
> >> > > > [email]davef@helixpoint.com[/email]
> >> > > > ______________________
> >> > > >
> >> > > >
> >> > >
> >> > >
> >> >
> >> >
> >>
> >>

> >

>

[daphish@msn.com]

oops my bad you could do it as
dr1("catnum") is nothing

On Thu, 26 Jun 2003 16:10:41 -0400, "Marina"
<zlatkinam@nospam.hotmail.com> wrote:

>There is no point to doing that. dr1.Read returned false - hence no rows.
>Neither of these things will work. The structure needs to be
>
>If dr1.Read() Then
>
>If IsDbNull(dr1("Catnum") Then
>....
>End If
>
>End If
><daphish@msn.com> wrote in message
>news:h0kmfv4iodtvt10qe8n4tracbsjl42f7ao@4ax.com.. .

>> There is a difference between dbnull and the object being null. You
>> also need to check if the object doesn't exists as well
>>
>> if not dr1("Catnum") is vbnullstring orelse isdbnull(dr1("catnum")
>> then
>>
>>
>> -dwayne
>>
>>
>> On Thu, 26 Jun 2003 15:47:53 -0400, "Helixpoint" <dave@helixpoint.com>
>> wrote:
>>

>> >I get an error when it checks for NULL???
>> >
>> >
>> >
>> >"Marina" <zlatkinam@nospam.hotmail.com> wrote in message
>> >news:unyL3sBPDHA.2228@tk2msftngp13.phx.gbl...
>> >> If you figured out that no rows were returned, then what's the problem?
>> >>
>> >> "Helixpoint" <dave@helixpoint.com> wrote in message
>> >> news:OT6UkqBPDHA.2788@TK2MSFTNGP10.phx.gbl...
>> >> > Not to be a jerk, but I figured that out.
>> >> >
>> >> >
>> >> > "Marina" <zlatkinam@nospam.hotmail.com> wrote in message
>> >> > news:useiulBPDHA.2284@TK2MSFTNGP11.phx.gbl...
>> >> > > Looks like there were no rows returned. dr1.Read returned false.
>> >> > >
>> >> > > "Helixpoint" <dave@helixpoint.com> wrote in message
>> >> > > news:OyEoEjBPDHA.2228@tk2msftngp13.phx.gbl...
>> >> > > > Dim dr1 As SqlDataReader =
>> >> MachCodeListID.GetSingleMachCode(thecodesID)
>> >> > > >
>> >> > > > ' Read first row from database
>> >> > > >
>> >> > > > dr1.Read()
>> >> > > >
>> >> > > > If IsDBNull(dr1("CATNUM")) Then '**************** This is where I

>am

>> >> > > getting
>> >> > > > the error??????
>> >> > > >
>> >> > > > thecatnum = 0
>> >> > > >
>> >> > > > Else
>> >> > > >
>> >> > > > thecatnum = dr1("CATNUM")
>> >> > > >
>> >> > > > End If
>> >> > > >
>> >> > > >
>> >> > > > --
>> >> > > >
>> >> > > > ______________________
>> >> > > > David Fetrow
>> >> > > > HelixPoint LLC.
>> >> > > > [url]http://www.helixpoint.com[/url]
>> >> > > > [email]davef@helixpoint.com[/email]
>> >> > > >
>> >> > > > Interested in Affordable Email Marketing?
>> >> > > > Check out the HelixMailer at
>> >[url]http://www.helixpoint.com/helixmailer.asp[/url]
>> >> > > > If you are interested in becoming a Reseller of HelixPoint

>products,

>> >> > > contact
>> >> > > > [email]davef@helixpoint.com[/email]
>> >> > > > ______________________
>> >> > > >
>> >> > > >
>> >> > >
>> >> > >
>> >> >
>> >> >
>> >>
>> >>
>> >

>>

>

[Marina]

No, my point is you could not do anything that would mean getting the column
value from the datareader.

The mere call to dr1("catnum") raises the error. There is no row - so no
column value for "catnum" - because there is no row!!

That's why the if statement for dr1.Read - to make sure there is a row
before you try to look at one of its columns.

<daphish@msn.com> wrote in message
news:oklmfvgnfogaigdbpu50t8udcg4h4jnu6u@4ax.com...

> oops my bad you could do it as
> dr1("catnum") is nothing
>
> On Thu, 26 Jun 2003 16:10:41 -0400, "Marina"
> <zlatkinam@nospam.hotmail.com> wrote:
>

> >There is no point to doing that. dr1.Read returned false - hence no

rows.

> >Neither of these things will work. The structure needs to be
> >
> >If dr1.Read() Then
> >
> >If IsDbNull(dr1("Catnum") Then
> >....
> >End If
> >
> >End If
> ><daphish@msn.com> wrote in message
> >news:h0kmfv4iodtvt10qe8n4tracbsjl42f7ao@4ax.com.. .

> >> There is a difference between dbnull and the object being null. You
> >> also need to check if the object doesn't exists as well
> >>
> >> if not dr1("Catnum") is vbnullstring orelse isdbnull(dr1("catnum")
> >> then
> >>
> >>
> >> -dwayne
> >>
> >>
> >> On Thu, 26 Jun 2003 15:47:53 -0400, "Helixpoint" <dave@helixpoint.com>
> >> wrote:
> >>
> >> >I get an error when it checks for NULL???
> >> >
> >> >
> >> >
> >> >"Marina" <zlatkinam@nospam.hotmail.com> wrote in message
> >> >news:unyL3sBPDHA.2228@tk2msftngp13.phx.gbl...
> >> >> If you figured out that no rows were returned, then what's the

problem?

> >> >>
> >> >> "Helixpoint" <dave@helixpoint.com> wrote in message
> >> >> news:OT6UkqBPDHA.2788@TK2MSFTNGP10.phx.gbl...
> >> >> > Not to be a jerk, but I figured that out.
> >> >> >
> >> >> >
> >> >> > "Marina" <zlatkinam@nospam.hotmail.com> wrote in message
> >> >> > news:useiulBPDHA.2284@TK2MSFTNGP11.phx.gbl...
> >> >> > > Looks like there were no rows returned. dr1.Read returned false.
> >> >> > >
> >> >> > > "Helixpoint" <dave@helixpoint.com> wrote in message
> >> >> > > news:OyEoEjBPDHA.2228@tk2msftngp13.phx.gbl...
> >> >> > > > Dim dr1 As SqlDataReader =
> >> >> MachCodeListID.GetSingleMachCode(thecodesID)
> >> >> > > >
> >> >> > > > ' Read first row from database
> >> >> > > >
> >> >> > > > dr1.Read()
> >> >> > > >
> >> >> > > > If IsDBNull(dr1("CATNUM")) Then '**************** This is

where I

> >am

> >> >> > > getting
> >> >> > > > the error??????
> >> >> > > >
> >> >> > > > thecatnum = 0
> >> >> > > >
> >> >> > > > Else
> >> >> > > >
> >> >> > > > thecatnum = dr1("CATNUM")
> >> >> > > >
> >> >> > > > End If
> >> >> > > >
> >> >> > > >
> >> >> > > > --
> >> >> > > >
> >> >> > > > ______________________
> >> >> > > > David Fetrow
> >> >> > > > HelixPoint LLC.
> >> >> > > > [url]http://www.helixpoint.com[/url]
> >> >> > > > [email]davef@helixpoint.com[/email]
> >> >> > > >
> >> >> > > > Interested in Affordable Email Marketing?
> >> >> > > > Check out the HelixMailer at
> >> >[url]http://www.helixpoint.com/helixmailer.asp[/url]
> >> >> > > > If you are interested in becoming a Reseller of HelixPoint

> >products,

> >> >> > > contact
> >> >> > > > [email]davef@helixpoint.com[/email]
> >> >> > > > ______________________
> >> >> > > >
> >> >> > > >
> >> >> > >
> >> >> > >
> >> >> >
> >> >> >
> >> >>
> >> >>
> >> >
> >>

> >

>