Question

I got a few queries built dynamically by my scripts. They usually fit the following template:

SELECT ... 
FROM ... 
JOIN ... 
WHERE ... (lots of filters, search conditions, etc. here) ... 
ORDER BY (optional) ... 
LIMIT (optional) ... OFFSET (optional)

I want to remove the LIMIT and OFFSET parts from the query. I used

$sql_entitati = implode("LIMIT", explode("LIMIT", $sql_entitati, -1));

to do it but then it hit me: what if there’s no LIMIT in the query and what if the only LIMIT is somewhere in the where clauses?

So my question to you is: How can I safely remove everything after the LIMIT key word, without screwing it up if there’s no LIMIT and/or there’s a “LIMIT” somewhere in the where clause? All this done in php.

A bit of an edit for clarity:

the algorithm i use:

$sql = implode("LIMIT", explode("LIMIT", $sql, -1));

Will work on 99% of the cases. The problem occurs when the “LIMIT” key word at the end is missing, AND there is “LIMIT” written somewhere in the conditions. for example:

 SELECT * FROM table WHERE bla = 'SPEED LIMIT' ORDER BY table.a

this is the problem i need to tackle.

Solved using the following algorithm (Credit to techfoobar):

    $p = strrpos($sql, "LIMIT");
    if($p !== false) {
        $q = strpos($sql, ")", $p);
        $r = strpos($sql, "'", $p);
        $s = strpos($sql, "\"", $p);
        if($q === false && $r === false && $s === false)
            $sql = substr($sql, 0, $p);
    }

Answer 1

You should do something like:

1. Get the position of the last “LIMIT” – store this position in say, p
2. Ensure that you do not have a ")" character after p – if so, it is part of some inner query inside a condition etc..
3. Ensure that you do not have a "'" character after p – if so, it is part of some user input string
4. If steps 2 and 3 are passed, strip off everything after p

More hints:

• For step 1 – use strrpos for the last occurrence of LIMIT
• For steps 2 and 3, use strpos with p as the search start offset
• For step4, use substr to strip off everything after p