Re: JDBC: getMoreResults() versus rs.next() & autoGeneratedKeys

From:

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 20 Dec 2013 19:08:17 -0500

Message-ID:

<52b4dbf5$0$304$14726298@news.sunsite.dk>

On 12/20/2013 9:07 AM, Andreas Leitgeb wrote:

I have to write code to execute runtime-specified SQL-statements,
and there are two things that I wasn't able to understand from reading
the javadocs:

1.)
When would one call .getMoreResults() on a statement instead of just
another rs.next() on the first one (obtained from stmnt.getResultSet())?
Are these equivalent, or is there really a concept of multiple ResultSets,
each of which has its own independent set of rows?

Yes.

Some databases support stored procedures returning multiple
result sets.

It is relative common in the MS SQLServer and Sybase ASE world.

Ultra simple example:

         CallableStatement cstmt = con.prepareCall("{CALL test()}");
         cstmt.execute();
         ResultSet rs = cstmt.getResultSet();
         while(rs.next()) {
             System.out.println(rs.getInt(1));
         }
         rs.close();
         cstmt.getMoreResults();
         rs = cstmt.getResultSet();
         while(rs.next()) {
             System.out.println(rs.getInt(1));
         }
         rs.close();

getMoreResults() returns a boolean whether there are more result set,
but typical you will know how many result sets there will be.

Note that the different result sets does not need to have same
number of columns or same column types.

Arne