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NewbieNotes is a little series of tips for people who are new to PHP to give them a few handy tips that the more experienced of us use often
I use this one all the time...
A little function saves you lots of lines and time in a database-heavy script.
When you're new at this you're quite likely to keep on writing the same thing over and over again. Wrap it up in one nice little function and call the fucntion instead.
| <?php
// alter the following four lines to your liking
$sql_host = "localhost";
$sql_user = "username";
$sql_pass = "password";
$sql_data = "database";
function open_mysql_link()
{
if($link = mysql_pconnect($GLOBALS["sql_host",
$GLOBALS["sql_user"], $GLOBALS["sql_pass"]))
{
if(!mysql_select_db($GLOBALS["sql_data"], $link))
{
$link = 0;
}
}
return $link;
}
?> | |
Armed with this trifle you can open a link to MySQL, connect to your database and get on with the rest of it without introducing hard to find bugs from the odd typo.
Usage Example:
| <?php
if($link = open_mysql_link())
{
$sql = "select program, time, channel from tv";
if($res = mysql_query($sql, $link))
{
while($row = mysql_fetch_object($res))
{
// Print tonight's TV listing
}
else echo mysql_error()."<br>\n$sql<br>\n";
}
else echo mysql_error()."<br>\n";
}
?> | |
Note that it's important to check what you got back from a call to MySQL. You often see code that never checks if things went as expected. Your database might have stopped running for some reason, you might have an error in your SQL - a multitude of things can stops something as simple as the above functioning.
CHECK what you get back is what you should have back! It's all detailed in the manual.
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| | | | Top Up wrote : 1102
Thats really cool I just got to know mysql_fetch_object ;p
I liked your code (though I would use mysql_connect instead of mysql_pconnect since the second kills the server after many requests).. and here is your code after my editings:
function open_mysql_link(){
global $db;
if($link = mysql_connect($db[`server`], $db[`username`], $db[`password`]))
if(!mysql_select_db($db[`database`], $link)) $link = 0;
return $link;
}
$sql = "select * from page";
if($res = mysql_query($sql, $link_id))
while($row = mysql_fetch_object($res)){
echo $row->title."<br>";
}
else echo mysql_error()."<br>\n$sql<br>\n";
| | | | Simon Booth wrote :1105
Using connect rather than pconnect you should mysql_close($link) at the end
Actually, although not illustrated above you should also free the result when you`re done with it
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