Question

Currently, these are the preparations I’m making:

1. Convert to lowercase.
2. Strip HTML tags.
3. Check if tag already exists

Are there any other things that I consider?

note: Tags may be in Arabic.

here the method i use

function sanitize_tag($tag){

//strip slashes
if(get_magic_quotes_gpc()) {
    $tag = stripslashes(trim($tag));
} 
//Remove white spaces
$tag = preg_replace('/\s\s+/',' ',$tag);
$tag = trim($tag);
$tag = ltrim($tag);
$tag=filter_var($tag, FILTER_SANITIZE_STRING);
return $tag;

}

Answer 1

If you are going to implement a FULLTEXT tag searching scheme (like mysqlicious), make sure that your tags do not include word separators.

Say, a dash (-) is a word separator in MySQL, while an underscore (_) is not.

So a search like this:

MATCH(tags) AGAINST ('+server' IN BOOLEAN MODE)

will incorrectly return sql-server but (correctly) will not return sql_server.