Re: [PHP] Re: mysql_num_rows
First, there is no reason to do mycounter like this
when mysql_num_rows() will work perfectly. It's not
based on any certain column numbers or primary keys.
Although if you're suggesting this method to simply
print 0-n in the loop (as users may want to know the
row number of output not any id number) then that's
good altough it's not really a counter in this case.
Second, we assume this person wants a count for
informational purposes, to go along with the
data in which case mysql_num_rows() is your best
bet. It means having a count before the data is
printed/used. And checking the number or rows
returned before fetching is a form of error handling
as well as if it equals 0 than there is no data to
fetch. But if one ONLY wants a number of rows count,
doing SELECT count(*)... works great as suggested
below.
Regards,
Philip Olson
On Wed, 18 Dec 2002, liljim wrote:
Hi John,
John Taylor-Johnston wrote in message:
I use $mycounter, not saying it is pretty. But if you have a whole bunch
of stuff deleted, your last id might be worth a lot more than the actual
number of rows.
$myconnection = mysql_connect($server,$user,$pass);
mysql_select_db($db,$myconnection);
$news = mysql_query('select * from '.$table.' where '.$where.' order by id
asc');
$mycounter = 0;
while ($mydata = mysql_fetch_object($news))
{
$mycounter++;
}
Have you ever considered just doing a count()?
$count = @mysql_query(select count(*) from [table(s)] where [criteria
[group by something]]);
$total = mysql_result($count, 0);
That will return the number of rows in your table(s). It's also much quicker
and less resource intensive, particularly with large datasets. :)
James
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Re: [PHP] Re: mysql_num_rows
I would also tend to do a count(*) as well as the main query if I intend to
use pagination (with the help of LIMIT in the main query).
Suppose, for example, you're limiting to 30 news posts per page, and from
calculations there are only 2 pages that fall into the criteria, then trying
to bring the result set back on page 3 when it doesn't exist will result
in a warning. Also, you'll want to know how many pages of the news post
there are...
Brief Example (assuming $page has already been validated as an integer):
$num = 30; // per page
$total = 49; // result from count(*)
$total_pages = ceil($total/$num);
if($page $total_pages)
{
$page = $total_pages;
}
// Main query.
// select [whatever] from [table(s)] where [criteria] [whateverelse] limit
. (($page*$num)-$num) . ,$num;
James
Philip Olson [EMAIL PROTECTED] wrote in message
Pine.BSF.4.10.10212181637090.4483-10@localhost">news:Pine.BSF.4.10.10212181637090.4483-10@localhost...
First, there is no reason to do mycounter like this
when mysql_num_rows() will work perfectly. It's not
based on any certain column numbers or primary keys.
Although if you're suggesting this method to simply
print 0-n in the loop (as users may want to know the
row number of output not any id number) then that's
good altough it's not really a counter in this case.
Second, we assume this person wants a count for
informational purposes, to go along with the
data in which case mysql_num_rows() is your best
bet. It means having a count before the data is
printed/used. And checking the number or rows
returned before fetching is a form of error handling
as well as if it equals 0 than there is no data to
fetch. But if one ONLY wants a number of rows count,
doing SELECT count(*)... works great as suggested
below.
Regards,
Philip Olson
On Wed, 18 Dec 2002, liljim wrote:
Hi John,
John Taylor-Johnston wrote in message:
I use $mycounter, not saying it is pretty. But if you have a whole
bunch
of stuff deleted, your last id might be worth a lot more than the actual
number of rows.
$myconnection = mysql_connect($server,$user,$pass);
mysql_select_db($db,$myconnection);
$news = mysql_query('select * from '.$table.' where '.$where.' order
by id
asc');
$mycounter = 0;
while ($mydata = mysql_fetch_object($news))
{
$mycounter++;
}
Have you ever considered just doing a count()?
$count = @mysql_query(select count(*) from [table(s)] where [criteria
[group by something]]);
$total = mysql_result($count, 0);
That will return the number of rows in your table(s). It's also much
quicker
and less resource intensive, particularly with large datasets. :)
James
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Re: [PHP] Re: mysql_num_rows
And now mysql4 allows doing this another way, I *assume*
this new way is slightly faster then the additional
count() although I haven't tested it and wonder if it
affects mysql_num_rows()...
See: SQL_CALC_FOUND_ROWS()
http://www.mysql.com/doc/en/Miscellaneous_functions.html
Regards,
Philip Olson
On Wed, 18 Dec 2002, liljim wrote:
I would also tend to do a count(*) as well as the main query if I intend to
use pagination (with the help of LIMIT in the main query).
Suppose, for example, you're limiting to 30 news posts per page, and from
calculations there are only 2 pages that fall into the criteria, then trying
to bring the result set back on page 3 when it doesn't exist will result
in a warning. Also, you'll want to know how many pages of the news post
there are...
Brief Example (assuming $page has already been validated as an integer):
$num = 30; // per page
$total = 49; // result from count(*)
$total_pages = ceil($total/$num);
if($page $total_pages)
{
$page = $total_pages;
}
// Main query.
// select [whatever] from [table(s)] where [criteria] [whateverelse] limit
. (($page*$num)-$num) . ,$num;
James
Philip Olson [EMAIL PROTECTED] wrote in message
Pine.BSF.4.10.10212181637090.4483-10@localhost">news:Pine.BSF.4.10.10212181637090.4483-10@localhost...
First, there is no reason to do mycounter like this
when mysql_num_rows() will work perfectly. It's not
based on any certain column numbers or primary keys.
Although if you're suggesting this method to simply
print 0-n in the loop (as users may want to know the
row number of output not any id number) then that's
good altough it's not really a counter in this case.
Second, we assume this person wants a count for
informational purposes, to go along with the
data in which case mysql_num_rows() is your best
bet. It means having a count before the data is
printed/used. And checking the number or rows
returned before fetching is a form of error handling
as well as if it equals 0 than there is no data to
fetch. But if one ONLY wants a number of rows count,
doing SELECT count(*)... works great as suggested
below.
Regards,
Philip Olson
On Wed, 18 Dec 2002, liljim wrote:
Hi John,
John Taylor-Johnston wrote in message:
I use $mycounter, not saying it is pretty. But if you have a whole
bunch
of stuff deleted, your last id might be worth a lot more than the actual
number of rows.
$myconnection = mysql_connect($server,$user,$pass);
mysql_select_db($db,$myconnection);
$news = mysql_query('select * from '.$table.' where '.$where.' order
by id
asc');
$mycounter = 0;
while ($mydata = mysql_fetch_object($news))
{
$mycounter++;
}
Have you ever considered just doing a count()?
$count = @mysql_query(select count(*) from [table(s)] where [criteria
[group by something]]);
$total = mysql_result($count, 0);
That will return the number of rows in your table(s). It's also much
quicker
and less resource intensive, particularly with large datasets. :)
James
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
--
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To unsubscribe, visit: http://www.php.net/unsub.php
--
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