SQL, EXECUTEREADER

[Givisiez]

Hi

I'm programming a windows application. I store values on a SQL-
database.
Now I've a problem reading the values stored.
I want to read a whole column from a table. I tried my SQL Command in
the "Query" from the Microsoft Visual Studio. There I get exactly the
values, which I want.
When I use the same command with a ExecuteReader, the only value which
I get for "reader" is:
System.Data.Sql Client.SqlDataR eader
But I expect a table of values with float values. Does anybody has an
Idea where I made a mistake?

SqlDataReader reader;

try
{
SQLComm.Command Text = "SELECT r.valeur FROM
Resultats_mesur e_testeur ...

SQLComm.Connect ion = conn;
conn.Open();
reader = SQLComm.Execute Reader();
if (reader.HasRows )
{
reader.Read();
test = reader.GetFloat (1);
}
In test I expect a value like "10" or something like that. But when I
debug I got an Error, Indexoutofbound exception.

Thanks for any help in advance!
Cheers,
Marco

[sloan]

The array is 0 based.

test = reader.GetFloat (0);
When in doubt , write DEVELOPMENT/DEBUG code like thisl
object o = reader.GetValue ( N ) ;

Where N is an ordinal number.

and put a watch on "o".

Do not do this for production code.



"Givisiez" <mw*****@contri nex.chwrote in message
news:11******** **************@ w5g2000hsg.goog legroups.com...

Hi

I'm programming a windows application. I store values on a SQL-
database.
Now I've a problem reading the values stored.
I want to read a whole column from a table. I tried my SQL Command in
the "Query" from the Microsoft Visual Studio. There I get exactly the
values, which I want.
When I use the same command with a ExecuteReader, the only value which
I get for "reader" is:
System.Data.Sql Client.SqlDataR eader
But I expect a table of values with float values. Does anybody has an
Idea where I made a mistake?

SqlDataReader reader;

try
{
SQLComm.Command Text = "SELECT r.valeur FROM
Resultats_mesur e_testeur ...

SQLComm.Connect ion = conn;
conn.Open();
reader = SQLComm.Execute Reader();
if (reader.HasRows )
{
reader.Read();
test = reader.GetFloat (1);
}
In test I expect a value like "10" or something like that. But when I
debug I got an Error, Indexoutofbound exception.

Thanks for any help in advance!
Cheers,
Marco

[Givisiez]

Thanks for your quick answer!!

I tried as you described:
object o = reader.GetValue ( N ) ;

for N=0, I get a value, in my case 36, that's great!!! I recive the
value which I should.
But for N=1, I've an exception "IndexOutOfrang eException". But it is a
table with more than 20 values..
So why haven't I access to the other Values?

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

"Givisiez" <mw*****@contri nex.chwrote in message
news:11******** **************@ g4g2000hsf.goog legroups.com...

Thanks for your quick answer!!

I tried as you described:
object o = reader.GetValue ( N ) ;

for N=0, I get a value, in my case 36, that's great!!! I recive the
value which I should.
But for N=1, I've an exception "IndexOutOfrang eException". But it is a
table with more than 20 values..
So why haven't I access to the other Values?

The table maybe has 20 rows but you are returning one column only "valeur "

Modify your query from:
SQLComm.Command Text = "SELECT r.valeur FROM Resultats_mesur e_testeur ...

to

SQLComm.Command Text = "SELECT * FROM Resultats_mesur e_testeur ...

[sloan]

You need to ask yourself?

Am I on a ROW, or am I accessing a COLUMN.

GetString(N) GetDecimal(N) , etc ,etc are COLUMN accessors, now row
accessors.
the while loop will loop over the ROWS.

int rowCounter = 0;
while (dataReader.Rea d())
{

rowCounter ++;
}

Console.WriteLi ne( rowCounter.ToSt ring() ) ;

"Givisiez" <mw*****@contri nex.chwrote in message
news:11******** **************@ g4g2000hsf.goog legroups.com...

Thanks for your quick answer!!

I tried as you described:
object o = reader.GetValue ( N ) ;

for N=0, I get a value, in my case 36, that's great!!! I recive the
value which I should.
But for N=1, I've an exception "IndexOutOfrang eException". But it is a
table with more than 20 values..
So why haven't I access to the other Values?

[Givisiez]

I tried out earlier SELECT * FROM, but then I get the whole table. The
Select command is right.
The solution was the while(datareade r.Read()) -Loop!!!
Thanks a lot for your help!!