[PHP] How *not* to assume MySQL will return data?
Hiya all,
Stock standard, and from most of the examples I've seen, standard MySQL
lookups via PHP utlises a while look to retrieve the data. All very nice
and well yes... But what if there is no data?
Here's a little example of what I want to do...
// Check for inportaint notices for the contact.
echo table width=\100%\ class=\td\\n;
echo tr\n;
echo td colspan=\2\ valign=\top\ class=\subhead\\n;
echo buImportant notes:/u/bbr\n;
echo /td\n;
echo /tr\n;
$SQL = mysql_query(SELECT MessageID, MessageTitle FROM contactmessages
WHERE ContactID=' . $_SESSION['ContactID'] . ' AND MessageRead='n';);
while ($ContactMessageList = mysql_fetch_array($SQL)) {
echo tr\n;
echo td align=\left\ valign=\top\a
href=\/profile/readmsg.php?MessageID= . $ContactMessageList['MessageID'] .
\ alt=\Read Message\ border=\0\img src=\/lib/images/arrow.gif\
border=\0\/td\n;
echo td align=\left\ valign=\top\ .
$ContactMessageList['MessageTitle'] . /td\n;
echo /tr\n;
}
echo /table\n;
echo br\n;
From this example, this block would be printed evertime. Whether the
contact has actual messages or not. How would I go about in a instance like
this, to use a MySQL check and only print the block if $SQL will actually
return data ?
In this case, can I do something like...
if ($SQL = mysql_query(something) {
print the block
while (do the actualy mysql lookup) {
print data
}
}
Spanks everyone :)
--
me
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Re: [PHP] How *not* to assume MySQL will return data?
H.
There's no way to do it *without* having to submit two queries to the
database? I'm thinking load wise here. The query (or block), would be
displayed on every single page in my app - sort of like a shared border type
thing...
Now, when I have say, 20 pages in the site, 250 concurrent users (or active
sessions) on the site - which, can happy very quickly - the load on the
database is going to be -very- high So I'm kind of looking for a way
how I can do this, with as few queries as possible, to put as little stress
on the database as I can...
But yes, if there is no otherway to do it, then I guess this would have to
do
Kind Regards,
Chris Knipe
MegaLAN Corporate InterNetworking Services
Tel: +27 21 854 7064
Cell: +27 72 434 7582
- Original Message -
From: Nathan [EMAIL PROTECTED]
To: Chris Knipe [EMAIL PROTECTED]
Sent: Monday, May 13, 2002 7:12 PM
Subject: Re: [PHP] How *not* to assume MySQL will return data?
if (mysql_num_rows($query) 0) {
print crud
}
else {
echo Query succeeded, but produced no results;
}
Is that what you mean?
- Original Message -
From: Chris Knipe [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Monday, May 13, 2002 8:46 AM
Subject: [PHP] How *not* to assume MySQL will return data?
Hiya all,
Stock standard, and from most of the examples I've seen, standard MySQL
lookups via PHP utlises a while look to retrieve the data. All very nice
and well yes... But what if there is no data?
Here's a little example of what I want to do...
// Check for inportaint notices for the contact.
echo table width=\100%\ class=\td\\n;
echo tr\n;
echo td colspan=\2\ valign=\top\ class=\subhead\\n;
echo buImportant notes:/u/bbr\n;
echo /td\n;
echo /tr\n;
$SQL = mysql_query(SELECT MessageID, MessageTitle FROM
contactmessages
WHERE ContactID=' . $_SESSION['ContactID'] . ' AND MessageRead='n';);
while ($ContactMessageList = mysql_fetch_array($SQL)) {
echo tr\n;
echo td align=\left\ valign=\top\a
href=\/profile/readmsg.php?MessageID= . $ContactMessageList['MessageID']
.
\ alt=\Read Message\ border=\0\img src=\/lib/images/arrow.gif\
border=\0\/td\n;
echo td align=\left\ valign=\top\ .
$ContactMessageList['MessageTitle'] . /td\n;
echo /tr\n;
}
echo /table\n;
echo br\n;
From this example, this block would be printed evertime. Whether the
contact has actual messages or not. How would I go about in a instance
like
this, to use a MySQL check and only print the block if $SQL will actually
return data ?
In this case, can I do something like...
if ($SQL = mysql_query(something) {
print the block
while (do the actualy mysql lookup) {
print data
}
}
Spanks everyone :)
--
me
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
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Re: [PHP] How *not* to assume MySQL will return data?
On Tuesday 14 May 2002 01:36, Chris Knipe wrote: H. There's no way to do it *without* having to submit two queries to the database? I'm thinking load wise here. The query (or block), would be displayed on every single page in my app - sort of like a shared border type thing... Now, when I have say, 20 pages in the site, 250 concurrent users (or active sessions) on the site - which, can happy very quickly - the load on the database is going to be -very- high So I'm kind of looking for a way how I can do this, with as few queries as possible, to put as little stress on the database as I can... But yes, if there is no otherway to do it, then I guess this would have to do It's just a matter of structuring your code properly. Separate code from HTML. Have your regular while-loop reading all the results into an array. If array is not empty then print your stuff out, otherwise don't print anything. -- Jason Wong - Gremlins Associates - www.gremlins.com.hk Open Source Software Systems Integrators * Web Design Hosting * Internet Intranet Applications Development * /* Virtual means never knowing where your next byte is coming from. */ -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] How *not* to assume MySQL will return data?
$result = mysql_query(...);
if($row = mysql_fetch_array($result))
{
do {
//loop through results
}while($row = mysql_fetch_array($result));
}
else
{ echo No rows returned; }
You could also just check mysql_num_rows() to see if any were returned and
base your if off of that.
---John Holmes...
- Original Message -
From: Chris Knipe [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Monday, May 13, 2002 10:46 AM
Subject: [PHP] How *not* to assume MySQL will return data?
Hiya all,
Stock standard, and from most of the examples I've seen, standard MySQL
lookups via PHP utlises a while look to retrieve the data. All very nice
and well yes... But what if there is no data?
Here's a little example of what I want to do...
// Check for inportaint notices for the contact.
echo table width=\100%\ class=\td\\n;
echo tr\n;
echo td colspan=\2\ valign=\top\ class=\subhead\\n;
echo buImportant notes:/u/bbr\n;
echo /td\n;
echo /tr\n;
$SQL = mysql_query(SELECT MessageID, MessageTitle FROM
contactmessages
WHERE ContactID=' . $_SESSION['ContactID'] . ' AND MessageRead='n';);
while ($ContactMessageList = mysql_fetch_array($SQL)) {
echo tr\n;
echo td align=\left\ valign=\top\a
href=\/profile/readmsg.php?MessageID= . $ContactMessageList['MessageID']
.
\ alt=\Read Message\ border=\0\img src=\/lib/images/arrow.gif\
border=\0\/td\n;
echo td align=\left\ valign=\top\ .
$ContactMessageList['MessageTitle'] . /td\n;
echo /tr\n;
}
echo /table\n;
echo br\n;
From this example, this block would be printed evertime. Whether the
contact has actual messages or not. How would I go about in a instance
like
this, to use a MySQL check and only print the block if $SQL will actually
return data ?
In this case, can I do something like...
if ($SQL = mysql_query(something) {
print the block
while (do the actualy mysql lookup) {
print data
}
}
Spanks everyone :)
--
me
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
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