Notes for How To Use Perl's DBI Modules

See http://dbi.perl.org or http://search.cpan.org/perldoc?DBI for the documentation.

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Some common variable names and their implied content,
  $dbh    Database handle object
  $sth    Statement handle object
  $drh    Driver handle object (rarely seen or used in applications)
  $h      Any of the handle types above ($dbh, $sth, or $drh)
  $rc     General Return Code  (boolean: true=ok, false=error)
  $rv     General Return Value (typically an integer)
  @ary    List of values returned from the database, typically a row of data
  $rows   Number of rows processed (if available, else -1)
  $fh     A filehandle

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From what I can tell, despite seeing it in Dale's old save_* code and in various
fcgi-bin Perl programs, one does not have to set
    $ENV{DB2DIR}="/home/inst1/sqllib";
    $ENV{INSTHOME}="/home/inst1";
    $ENV{PATH}.=":/home/inst1/sqllib/bin:/home/inst1/sqllib/adm:/home/inst1/sqllib/misc";
    $ENV{LD_LIBRARY_PATH}.=":/home/inst1/sqllib/lib";
in order to use DBI.  All you really need is
    $ENV{DB2INSTANCE}="inst1";          # Normally
or  $ENV{DB2INSTANCE}="caeadmin";       # On most dephds0nn systems (not 59 or 61)
or  $ENV{DB2INSTANCE}="db2inst1";       # On dephds069

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$dbh->rows is suppose to return the number of rows affected by the last command,
or -1 if the number of rows is not known or not available, but there's this caveat
for select statements,

   Generally, you can only rely on a row count after a non-SELECT execute
   (for some specific operations like UPDATE and DELETE), or after fetching
   all the rows of a SELECT statement.

   For SELECT statements, it is generally not possible to know how many rows will
   be returned except by fetching them all. Some drivers will return the number of
   rows the application has fetched so far, but others may return -1 until all rows
   have been fetched.

so it's basically worthless.