Regex with more than one OR/AND operator - regex

Question

I'm trying to match text that is:
a combination of numbers and letters, and might contain [:,.]
OR
a * character plus at least one number OR letter (not necessarily in this order)
Meaning my regex should match all these
Bf1305020008401 6798ubbii230693
Nettbank til: Troij iudh Betalt: 03.05.13
7509*30.04
*87589
but not these:
0205
252,25

Answer 1

Yes, regex alternation with | does not have the meaning in a character group (e.g. [a-z|0-9]) that it does elsewhere in a pattern. (Think of it as implied between characters & character ranges within a character group, making it redundant.)
Pattern
This pattern should do what you need:
^((?=^.{0,}[0-9])(?=^.{0,}[a-zA-Z])[0-9a-zA-Z :,.]{2,}|(?!^\*$)(?=^[0-9.a-zA-Z]{0,}\*[0-9.a-zA-Z]{0,})(?!^[0-9.a-zA-Z]{0,}\*[0-9.a-zA-Z]{0,}\*)[*0-9.a-zA-Z]{2,})$
It matches...
Bf1305020008401 6798ubbii230693
Nettbank til: Troij iudh Betalt: 03.05.13
7509*30.04
*87589
...and does not match...
0205
252,25
...as you require.
You can try the pattern with the inputs you specified in a regex fiddle.
Explanation
Some explanation for the 1st subpattern (on the left side of the |) matching your 1st set of match criteria:
(?=^.{0,}[0-9]) - Assert that a number appears in the string.
(?=^.{0,}[a-zA-Z]) - Assert that a letter also (i.e. AND) appears in the string.
[0-9a-zA-Z :,.]{2,} - "a combination of numbers and letters, and might contain [ :,.]" (assuming the aforementioned assertions)
Similarly, some explanation for the 2nd subpattern (on the right side of the |) matching your 2nd set of match criteria:
(?!^\*$) - Assert that the string is not just *.
(?=^[0-9.a-zA-Z]{0,}\*[0-9.a-zA-Z]{0,}) - Assert that the string contains *.
(?!^[0-9.a-zA-Z]{0,}\*[0-9.a-zA-Z]{0,}\*) - Assert that the string does not contain more than one *.
[*0-9.a-zA-Z]{2,} - "a * character + atleast one number OR letter (not necessarily in this order)" (assuming the aforementioned assertions)
There is probably room to sand & polish the pattern - especially the lookahead assertions for * in the second subpattern I suspect; but it works and conveys the strategy I employed of multiple lookahead assertions to constrain each of the two subpatterns to fit your requirements.

Answer 2

As you comment below, I think you dose want a full line match, and by saying number and letter, I think it means digits and letters both occurred in the right match.
And by saying "a * character + atleast one number OR letter" I suppose "*" occurs only once in match.
Maybe you could try this one:
(^(?=.*[a-zA-Z]+)(?=.*[0-9]+)[0-9a-zA-Z :,.]+$)|(^[a-zA-Z0-9.]*\*[a-zA-Z0-9.]+$)|(^[a-zA-Z0-9.]+\*[a-zA-Z0-9.]*$)
It matches:
Bf1305020008401 6798ubbii230693
Nettbank til: Troij iudh Betalt: 03.05.13
7509*30.04
*87589
123456*
.*.
test123
123test
But won't match any of:
0205
252,25
*
123*345*789
rebound
test
123
Original:
This should work
(^[A-Za-z0-9 ]*(([A-Za-z]+[ ]*[0-9]+)|([0-9]+[ ]*[A-Za-z]+))[A-Za-z0-9 ]*$)|(^\*[A-Za-z0-9]+$)