Get delimiters from preg_split in PHP

Question

My PHP code:

$cmd = 'SELECT var1 FROM var2 GROUP BY var3 LIMIT var4';
// split command
$p = preg_split('/SELECT|FROM|GROUP BY|LIMIT/si', $cmd);

Output:

Array
(
  [0] =>  
  [1] =>  var1 
  [2] =>  var2 
  [3] =>  var3
  [4] =>  var4
)

Is that output below possible?

Array
(
  [SELECT] => var1
  [FROM] => var2
  [GROUP BY] => var3
  [LIMIT] => var4
)

Or is there any way to get delimiters?

Answer 1

Have you considered using a SQL parser? You're bound to get wrong results with this regex-hack.

Checkout:

1. http://code.google.com/p/php-sql-parser
2. http://pear.php.net/package/SQL_Parser
3. PHP MySQL SQL parser (INSERT and UPDATE)

A demo with option 1:

#!/usr/bin/env php
<?php

// http://php-sql-parser.googlecode.com/svn/trunk/php-sql-parser.php
require_once('php-sql-parser.php');

$cmd = 'SELECT var1 FROM var2 GROUP BY var3 LIMIT var4';
$parser = new PHPSQLParser($cmd);
$parse_tree = $parser->parsed;

echo 'SELECT -> ' . $parse_tree['SELECT'][0]['base_expr'] . "\n";
echo 'FROM   -> ' . $parse_tree['FROM'][0]['table'] . "\n";
echo 'GROUP  -> ' . $parse_tree['GROUP'][0]['base_expr'] . "\n";
echo 'LIMIT  -> ' . $parse_tree['LIMIT']['end'] . "\n";

?>

produces:

SELECT -> var1
FROM   -> var2
GROUP  -> var3
LIMIT  -> var4

Answer 2

$cmd = 'SELECT var1 FROM var2 GROUP BY var3 LIMIT var4';

$array = array();
if(preg_match_all('/(SELECT|FROM|GROUP BY|LIMIT)\s+([^\s]+)/si', $cmd, $matches)) {
    $array = array_combine($matches[1], $matches[2]);
}

var_dump($array);

Result:

array
  'SELECT' => string 'var1' (length=4)
  'FROM' => string 'var2' (length=4)
  'GROUP BY' => string 'var3' (length=4)
  'LIMIT' => string 'var4' (length=4)