<?php
$sql = 'SELECT
    [Person].[Name]
    [Person].[Address],
    [Sales].[TotalAmount]';

preg_match_all('#\[[^]]+\]\.(\[[^]]+\])#', $sql, $found); // Match
$max = max(array_map('strlen', $found[1])); // Find max length

$new = preg_replace_callback('#\[[^]]+\]\.(\[[^]]+\])#', function($m)use($max){
    $string = $m[1].str_repeat(' ',$max - strlen($m[1])).' = '.$m[0];
	return($string);
}, $sql);
echo $new;
?>