Question

I want to check if a value for a MySQL Query contain % character (can appear multiple times) but not the escaped \%.

So it should match:

• '%test'
• '%test\%'
• 'test\\%' – should match because it’s escape the \ not the %
• '%test\%%'
• '\%test%test\%'

but not:

• 'test\%'
• '\%test\%'
• '\%test\%test\%'

I’m not good in Regular Expression, can someone help me on this?

Thanks in advance.

Edit:
I’m trying creating a PHP Library for generating SQL Query from an array, and maybe the generated query will be used mostly on MySQL.
So, the regex filtering process will be in PHP.

Sorry, I forgot to mention this.

Thanks

Answer 1

Check this on PHP code:

unset($str1,$str2,$str3,$str4,$str5,$str6,$str7);

$str1 = '%100'; 
$str2 = '%100\%';
$str3 = "100\\\\%";
$str4 = "%100\\%%";
$str5 = '100\%';
$str6 = "100\\\\\\\\%";
$str7 = "100\\\\\\%";
$str8 = "100\\\\\\\\\\\\%";
$str9 = "100\\\\\\\\\\\\\\%";

$reg_exp=  '/^%|[^\x5C]%|[^\x5C](\x5C\x5C)+%/';

echo $str1.' = '.preg_match($reg_exp, $str1).'<br />';
echo $str2.' = '.preg_match($reg_exp, $str2).'<br />';
echo $str3.' = '.preg_match($reg_exp, $str3).'<br />';
echo $str4.' = '.preg_match($reg_exp, $str4).'<br />';
echo $str5.' = '.preg_match($reg_exp, $str5).'<br />';
echo $str6.' = '.preg_match($reg_exp, $str6).'<br />';
echo $str7.' = '.preg_match($reg_exp, $str7).'<br />';
echo $str8.' = '.preg_match($reg_exp, $str8).'<br />';
echo $str9.' = '.preg_match($reg_exp, $str9).'<br />';

http://ideone.com/Bgq5bV