preg_match help required for password security

[pwebb]

Hi,

Could anyone please help with the preg_match expression I will need to perform the following.

I need it to check a password field for a password that contains :-

numeric chars (min of 1)
upper case letters (min of 1)
lower case letters (min of 1)
The password must be at least 6 characters and only be made up of upper and lower case letters and numbers.

Any help would be greatly appreciated.

Regards,