Why rs.next() before fetching data???

[parkarumesh]

Hi,

I have written a function as follows

public String fetchName(String query) throws Exception
{

stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
rs.next();
return (rs.getString(1));
}

If i don't write the statement,
rs.next and directly use rs.getString(1), i get exception

Why is it so, why do we need to move one record next???

Thanks

 

[Ingo R. Homann]

Hi,

I have written a function as follows

public String fetchName(String query) throws Exception
{

stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
rs.next();
return (rs.getString(1));
}

If i don't write the statement,
rs.next and directly use rs.getString(1), i get exception

Why is it so, why do we need to move one record next???

Because

(1) There may be more than one record in the result set.
(2) There may be no record in the result set.

You must be able to handle that!

Ciao,
Ingo

 

[Chris Diver]

Hi,

I have written a function as follows

public String fetchName(String query) throws Exception
{

stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(query);
rs.next();
return (rs.getString(1));
}

If i don't write the statement,
rs.next and directly use rs.getString(1), i get exception

Why is it so, why do we need to move one record next???

Thanks

I'm not entirely sure why it is. I'd imagine its a pointer
which starts before the first tuple in your result set.

Initially
-->
Row1
Row2
Row3
....

Calling rs.next() moves the pointer down.

....
--> Row1
Row2
....


But it does allow you to do

while(rs.next()){
//get elements
}

because rs.next() returns true when there is
another row and false if there was no next row.

Chris

 

[ishahdad]

A related question

I am doing something similar to this.. however what I want is to delete all except the last from the result set of a query I am executing.

My sql query gives a list of names that I want to delete except for the last one which I want to keep.

Is there something like rs->getlast() as well which would give me the last name from that result set? How do I implement this?

Appreciate your help

 

[ishahdad]

I am using C++