Re: Nest SQL queries and result sets?
"Mo" <dmittleider@gmail.com> wrote in
news:1154096487.984124.124920@s13g2000cwa.googlegroups.com:
These are two different databases. One is off an AS/400 mainframe and
I hope you don't expect to maintain referential integrity over such a
configuration. You'll get lots of orphaned child rows in the child table as
you delete rows in the parent table, for one.
the other is off a n AIX box running DB2 and eventually this will be
expanded for an Oracle database too.
What are you doing with the string that you're retrieving from the result
set?
Is the column that this string is retrieved from nullable? If so, then are
you doing appropriate null checks before using the string?
What is the exact line of code that the NPE's stacktrace points at? Is the
NPE in your code or is it in the JDBC driver's code? If the former, then
what is the exact line of code that is giving the NPE? If the latter, then
what is the line of code further up the stack trace that is your code?
Cheers
GRB
Greg R. Broderick wrote:
"Mo" <dmittleider@gmail.com> wrote in news:1154037754.863609.184420
@s13g2000cwa.googlegroups.com:
I'm trying to use a while loop to loop through a result set, and
inside that results set call another query. Like....
database_conn1 = new DBConnection(url, user, pass);
database_conn2 = new DBConnection(url, user, pass);
ResultSet records_conn1 = database_conn1.executeQuery(sqlstatment01);
while (records_conn1.next()) {
records1_conn.getString(1);
ResultSet records_conn2 =
database_conn2.executeQuery(sqlstatment02);
while (records_conn2.next()) { records2_conn.getString(1);
}
}
(I have try and catch around the while statements, just trying to
keep the code simple)
What happens is the outside result set gets the first record, the
inside record gets all of it's results and then it gives me a null
pointer exception. I'm not sure if it is because the inside result
set closes down everything or what. Is this even possible, or is
there a better way to do this?
I'd suggest collapsing the two queries into one query using a join on
the two tables and an ORDER BY clause to insure that one parent table's
rows stay together in the output results - it will save you multiple
round trips to the database at the cost of some denormalization.
Cheers
GRB
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