making sure SQL_CALC_FOUND_ROWS is in there

[sneakyimp]

So I'm working on a class to help me display paged tables of data. I want to let the user specify whatever query they are working on and then I need to make sure the MySQL query (sorry mysql only) has SQL_CALC_FOUND_ROWS in it so that I can easily get a total record count later.

I read the MySQL select syntax here and came up with this code:

if (strpos($this->sql, 'SQL_CALC_FOUND_ROWS') === false) {
	// CRIKEY!  get a load of this cumbersome expression.
	$this->sql = preg_replace('#(^\s*SELECT\s*(ALL|DISTINCT|DISTINCTROW){0,1}\s*(HIGH_PRIORITY){0,1}\s*(STRAIGHT_JOIN){0,1}\s*(SQL_SMALL_RESULT){0,1}\s*(SQL_BIG_RESULT){0,1}\s*(SQL_BUFFER_RESULT){0,1}\s*(SQL_CACHE|SQL_NO_CACHE){0,1}\s*)(.*)(\sFROM\s)#is', '\1SQL_CALC_FOUND_ROWS \9\10', $str);
}

1) Do we think that will always work? Can anyone think of a counterexample that breaks it?
2) Is there a simpler expression that'll work? That one seems like a real pain in the ass.

[dagon]

why not just use mysql_num_rows()

[sneakyimp]

SQL_CALC_FOUND_ROWS in your select query tells MySQL to calculate how many rows match your query if the limit clause is complete ignored. This is useful for paging data. You need to read the link i posted to the mysql docs:
http://dev.mysql.com/doc/refman/5.0/en/select.html

[dagon]

woops, forgot what it did