datareader.getstring(0) error

[Nakhi]

Hi,
my code is very simple.

dim cm as oledbcommand= new oledbcommand("select * from page " ,cn)
cn.open()
Dim dr As OleDbDataReader = cm.ExecuteReader()
dim cate=dr.getstring(1) 'error line"
label1.text=cate

but there is error for dr.getstring(1), the error reads:the data of this
column does not exist:
I am sure the second line exist(not null) and is string type.

when add a read() before the error line,then there is no error. And in
another sub, I can output the same datareader content using a do while
read() function.

Can anyone give me a hint?

Nakhi
From Lijinag,China.

[Ravikanth[MVP]]

Hi
Try with the following code:

RULE: Always call Read before accessing data.

myReader = myCommand.ExecuteReader();
// Always call Read before accessing data.
while (myReader.Read()) {
Console.WriteLine(myReader.GetInt32(0) + ", " +
myReader.GetString(1));
}


HTH
Ravikanth

>-----Original Message-----
>Hi,
>my code is very simple.
>
>dim cm as oledbcommand= new oledbcommand("select * from

page " ,cn)

> cn.open()
> Dim dr As OleDbDataReader = cm.ExecuteReader()
> dim cate=dr.getstring(1) 'error line"
> label1.text=cate
>
>but there is error for dr.getstring(1), the error

reads:the data of this

>column does not exist:
>I am sure the second line exist(not null) and is string

type.

>
>when add a read() before the error line,then there is

no error. And in

>another sub, I can output the same datareader content

using a do while

>read() function.
>
>Can anyone give me a hint?
>
>Nakhi
>From Lijinag,China.
>
>
>.
>

[Natty Gur]

Hi,

you must use Read() in order to populate the reader.

Natty Gur, CTO
Dao2Com Ltd.
28th Baruch Hirsch st. Bnei-Brak
Israel , 51114

Phone Numbers:
Office: +972-(0)3-5786668
Fax: +972-(0)3-5703475
Mobile: +972-(0)58-888377

Know the overall picture


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[Nakhi]

thanx,it works, that is move the cursor to the first line.

Nakhi
Lijiang,Yunnan,China,Asia.


"Natty Gur" <natty@dao2com.com> дÈëÏûÏ¢ÐÂÎÅ
:OvLkJvgSDHA.1912@tk2msftngp13.phx.gbl...

> Hi,
>
> you must use Read() in order to populate the reader.
>
> Natty Gur, CTO
> Dao2Com Ltd.
> 28th Baruch Hirsch st. Bnei-Brak
> Israel , 51114
>
> Phone Numbers:
> Office: +972-(0)3-5786668
> Fax: +972-(0)3-5703475
> Mobile: +972-(0)58-888377
>
> Know the overall picture
>
>
> *** Sent via Developersdex [url]http://www.developersdex.com[/url] ***
> Don't just participate in USENET...get rewarded for it!