Regex to get area and district codes from UK postcodes

Question

Basically, I need a regex that would match first sequence of letters in UK postcode (easy) and another regex which would match the following number (not so easy).

Examples of possible combinations and matches:

AA9A 9AA    regex1: AA    regex2: 9
A9A 9AA     regex1: A     regex2: 9
A9 9AA      regex1: A     regex2: 9
A99 9AA     regex1: A     regex2: 99
AA9 9AA     regex1: AA    regex2: 9
AA99 9AA    regex1: AA    regex2: 99

Spaces in poscodes are only there for clarity, they might or might not be there, therefor must be disregarded.

I could use some help with these two regular expressions, especially regex2 (matching the number). By the way, I'm gonna be running this in MySQL 5.6

UPDATE: Just to note: last 3 characters will always be ignored no matter what, that's the only pattern that always applies - it should be visible from my examples.

UPDATE2: Sorry if I wasn't clear enough before - I don't need to validate the post codes, I need to extract area and district codes.

UPDATE3: Just to emphasize again: white space must be disregarded, it could be AA99 9AA or AA999AA - in both cases the regex2 (extract number) should be 99

UPDATE4: Thanks for all your answers, unfortunately I just found out that MySQL can't extract regex matches. Way to go, MySQL, proving to be useless yet again.

Answer 1

You can use this regex:

([A-Z]+)([0-9]+).*?[A-Z0-9]{3}

and use matched group #1 and #2

Answer 2

this regex:

([A-Z]+)([0-9]+)([A-Z ]*[0-9][A-Z]{2})

works as follows according to RegexBuddy 4 simulation of MySQL's POSIX ERE regex implementation:

Input     G1   G2   G3
--------  ---  ---  ------
AA9A 9AA  AA   9    A 9AA
A9A 9AA   A    9    A 9AA
A9 9AA    A    9     9AA
A99 9AA   A    99    9AA
AA9 9AA   AA   9     9AA
AA99 9AA  AA   99    9AA
AA9A9AA   AA   9    A9AA
A9A9AA    A    9    A9AA
A99AA     A    9    9AA
A999AA    A    99   9AA
AA99AA    AA   9    9AA
AA999AA   AA   99   9AA

explanation:

([A-Z]+)    # captures one or more letters
([0-9]+)    # captures one or more digits
(           # starts 3rd capture group
 [A-Z ]*    # captures zero or more letters or space
 [0-9]      # captures exactly one digit
 [A-Z]{2}   # captures exactly two letters
)           # ends 3rd capture group

let me know if I missed a test case that doesn't work, and I'll see what I can do

Answer 3

"[A-Z](?:\\D\\d\\D|\\d\\D|\\d|\\d{2}|\\D\\d|\\D\\d\\d|EI)\\s??\\d{1}\\D{2}" works quite well for me. It is littlebit complicated because I use it to fetch zipcode from ONE LINE ADDRESS (whole address with city, country, street names etc, and not for validating zipcodes). I use it in my production environment.