Need help writing functions for accessing MySQL

becky

I am new to writing my own functions, but am quite familiar with both PHP and MySQL otherwise.

I am updating a site that has tons of instances of the following basic code:
$sql = "select DATE_FORMAT(datepublished, '%W, %M %y') from news where id = $id";
$result = mysql_query($sql);
$nicedate = mysql_result($result, 0);

I'd like to replace all of this junk with a custom function (as it appears several times on each page). I wrote this and put it in my constants.php file:

function formatdatetime ($tablename, $fieldname, $format, $selector)
{
$sql = "select DATEFORMAT($fieldname, '$format') from $tablename where id = $selector";
$result = mysql_query($sql);
echo mysql_result($result, 0);
}

It doesn't work, I think because the server is trying to evaluate the function as a literal query when it includes the constants.php file.

Can anyone tell me what I'm doing wrong and how to accomplish this?

bastien

from the calling page, then you need the Globals keyword to identify the variables that can be used by the function

see

http://www.php.net/manual/en/printwn/language.variables.scope.php

function formatdatetime ($tablename, $fieldname, $format, $selector)
{
Gobals $varname;
$sql = "select DATEFORMAT($fieldname, '$format') from $tablename where id = $selector";
$result = mysql_query($sql);
echo mysql_result($result, 0);
}

tomhath

What do you mean by "it doesn't work" ?

Is mysql_query returning an error (tough to tell, since you aren't checking for it)? Or are you getting a syntax error when the function is called?

becky

I was getting a "nto a valid result resource" error. However, I did as bastien suggested and it works fine now. I never really took the time to understand variable scope in PHP, so I assumed that all variables were global unless specified otherwise. Ooops! Anyway, this is what I came up with, and it's working GREAT.

function formatdatetime ($tablename, $fieldname, $format, $selector)
{
Global $nice;
$nicesql = "select DATE_FORMAT($fieldname, '$format') from $tablename where id = $selector";
$niceresult = mysql_query($nicesql);
$nice = mysql_result($niceresult, 0);
return $nice;
}

jeremuck

don't forget to do error checking.

never assume database queries will work.