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Full Discussion: perl: help with DBI
Top Forums Shell Programming and Scripting perl: help with DBI Post 302424535 by SFNYC on Tuesday 25th of May 2010 02:09:04 PM
Old 05-25-2010
What database are you using? There may be a way to code the SQL to return you some count or indicator when no rows are returned from your SELECT.

There is also a method called 'rows', but it does not work for SELECT statements.

From perldoc DBI:

Code:
$rv = $sth->rows;

Returns the number of rows affected by the last row-affecting command, or -1 if the number of rows is not known or not available.

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 use of the rows method or $DBI::rows with SELECT statements is not recommended.

One alternative method to get a row count for a SELECT is to execute a "SELECT COUNT(*) FROM ..." SQL statement with the same "..." as your query, and then fetch the row count from that.

 

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LEARN ABOUT DEBIAN

gtk2::pagesetup

Gtk2::PageSetup(3pm)					User Contributed Perl Documentation				      Gtk2::PageSetup(3pm)

NAME

       Gtk2::PageSetup - wrapper for GtkPageSetup

HIERARCHY

	 Glib::Object
	 +----Gtk2::PageSetup

METHODS

   pagesetup = Gtk2::PageSetup->new
   pagesetup = Gtk2::PageSetup->new_from_file ($file_name)
       o   $file_name (localized file name)

       May croak with a Glib::Error in $@ on failure.

       Since: gtk+ 2.12

   pagesetup = Gtk2::PageSetup->new_from_key_file ($key_file, $group_name)
       o   $key_file (Glib::KeyFile)

       o   $group_name (string or undef)

       May croak with a Glib::Error in $@ on failure.

       Since: gtk+ 2.12

   double = $setup->get_bottom_margin ($unit)
       o   $unit (Gtk2::Unit)

   $setup->set_bottom_margin ($margin, $unit)
       o   $margin (double)

       o   $unit (Gtk2::Unit)

   double = $setup->get_left_margin ($unit)
       o   $unit (Gtk2::Unit)

   $setup->set_left_margin ($margin, $unit)
       o   $margin (double)

       o   $unit (Gtk2::Unit)

   $setup->load_file ($file_name)
       o   $file_name (string)

       May croak with a Glib::Error in $@ on failure.

       Since: gtk+ 2.14

   $setup->load_key_file ($key_file, $group_name)
       o   $key_file (Glib::KeyFile)

       o   $group_name (string or undef)

       May croak with a Glib::Error in $@ on failure.

       Since: gtk+ 2.14

   pageorientation = $setup->get_orientation
   $setup->set_orientation ($orientation)
       o   $orientation (Gtk2::PageOrientation)

   double = $setup->get_page_height ($unit)
       o   $unit (Gtk2::Unit)

   double = $setup->get_page_width ($unit)
       o   $unit (Gtk2::Unit)

   double = $setup->get_paper_height ($unit)
       o   $unit (Gtk2::Unit)

   $setup->set_paper_size_and_default_margins ($size)
       o   $size (Gtk2::PaperSize)

   papersize = $setup->get_paper_size
   $setup->set_paper_size ($size)
       o   $size (Gtk2::PaperSize)

   double = $setup->get_paper_width ($unit)
       o   $unit (Gtk2::Unit)

   double = $setup->get_right_margin ($unit)
       o   $unit (Gtk2::Unit)

   $setup->set_right_margin ($margin, $unit)
       o   $margin (double)

       o   $unit (Gtk2::Unit)

   $setup->to_file ($file_name)
       o   $file_name (localized file name)

       May croak with a Glib::Error in $@ on failure.

       Since: gtk+ 2.12

   $setup->to_key_file ($key_file, $group_name)
       o   $key_file (Glib::KeyFile)

       o   $group_name (string or undef)

       Since: gtk+ 2.12

   double = $setup->get_top_margin ($unit)
       o   $unit (Gtk2::Unit)

   $setup->set_top_margin ($margin, $unit)
       o   $margin (double)

       o   $unit (Gtk2::Unit)

ENUMS AND FLAGS

   enum Gtk2::PageOrientation
       o   'portrait' / 'GTK_PAGE_ORIENTATION_PORTRAIT'

       o   'landscape' / 'GTK_PAGE_ORIENTATION_LANDSCAPE'

       o   'reverse-portrait' / 'GTK_PAGE_ORIENTATION_REVERSE_PORTRAIT'

       o   'reverse-landscape' / 'GTK_PAGE_ORIENTATION_REVERSE_LANDSCAPE'

   enum Gtk2::Unit
       o   'pixel' / 'GTK_UNIT_PIXEL'

       o   'points' / 'GTK_UNIT_POINTS'

       o   'inch' / 'GTK_UNIT_INCH'

       o   'mm' / 'GTK_UNIT_MM'

SEE ALSO

       Gtk2, Glib::Object

COPYRIGHT

       Copyright (C) 2003-2011 by the gtk2-perl team.

       This software is licensed under the LGPL.  See Gtk2 for a full notice.

perl v5.14.2							    2012-05-27						      Gtk2::PageSetup(3pm)
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