Column limit with php

mikeyb123

Hi All

I'm trying to create a function that allows me to dynamically check if a users input is too long to be entered in to a column? Please ignore the MAX function in the query thats my workaround.

function maxLength($value,$column,$table) {
	stripslashes($value);
	stripslashes($column);
	stripslashes($table);
	mysql_real_escape_string($value);
	mysql_real_escape_string($column);
	mysql_real_escape_string($table);

$sql = "SELECT MAX(".$column.") FROM ".$table." ";
if(!mysql_query($sql)) {
	die('mysql failed');
}

$len = strlen($value);
$maxlen = mysql_fetch_array($sql);
if($len > $maxlen[''.$column.'']) {
	return false;
} else {
	return true;
}	
}

Two things I am unsure about is:
1) Is there a way of getting the column limit i.e. if test VARCHAR(65) I need php to display 65?
2) Would the $maxlength array call work below?
if($len > $maxlen[''.$column.'']) {
return false;
} else {
return true;
}

Regards,
Mike

johanafm

MAX returns the highest value for a column among all the selected rows, so it has nothing to do with the max possible input length.

You may want to have a look at http://se.php.net/manual/en/mysqli-result.fetch-fields.php and http://se.php.net/manual/en/mysqli-stmt.result-metadata.php

But if you control the database yourself so that boundaries won't change without you knowing it, and somehow map data between tables and objects, e.g. using ORM, I'd recommend hard coding the max lengths and or min and max values in your classes' set member methods.

A more elaborate technique would be to keep a separte file(s) that desctibes all your tables/objects, either as SQL, PHP or some proprietary way, and then create a script that will produce the appropriate PHP and/or SQL code automatically. This way you will only have to make changes in one single place. And as an added upside, you don't have to write the basic code both for describing the db and your classes.

mikeyb123

I was just going to add the highest value in row 1 then use MAX and strlen() to limit the input(seems stupid now I've had some sleep). I like the separate file idea for the tables, I have already listed the tables and describe because my memory is useless 🙂 Thanks that helped a lot