Select only letters which are followed by a number - regex

Question

I am trying to select some codes from a PostgreSQl table.
I only want the codes that have numbers in them e.g
GD123
GD564
I don't want to pick any codes like `GDTG GDCNB
Here's my query so far:
select regexp_matches(no_, '[a-zA-Z0-9]*$')
from myschema.mytable
which of course doesn't work.
Any help appreciated.

Answer 1

The pattern to match a string that has at least 1 letter followed by at least 1 number is '[A-Za-z]+[0-9]+'.
Now, if the valid patterns had to start with two letters, and then have 3 digits after as your examples show, then replace the + with {2} & {4} respectively, and enclose the pattern in ^$, like this: '^[A-Za-z]{2}[0-9]{3}$'
The regex match operator is ~ which you can use in the where clause:
SELECT no_
FROM myschema.mytable
WHERE no_ ~ '[A-Za-z]+[0-9]+'

Answer 2

You may use
CREATE TABLE tb1
(s character varying)
;
INSERT INTO tb1
(s)
VALUES
('GD123'),
('12345'),
('GDFGH')
;
SELECT * FROM tb1 WHERE s ~ '^(?![A-Za-z]+$)[a-zA-Z0-9]+$';
Result:
Details
^ - start of string
(?![A-Za-z]+$) - a negative lookahead that fails the match if there are only letters to the end of the string
[a-zA-Z0-9]+ - 1 or more alphanumeric chars
$ - end of string.
If you want to avoid matching 12345, use
'^(?![A-Za-z]+$)(?![0-9]+$)[a-zA-Z0-9]+$'
Here, (?![0-9]+$) will similarly fail the match if, from the string start, all chars up to the end of the string are digits. Result:

Answer 3

smth like:
so=# with c(v) as (values('GD123'),('12345'),('GD ERT'))
select v ~ '[A-Z]{1,}[0-9]+', v from c;
?column? | v
----------+--------
t | GD123
f | 12345
f | GD ERT
(3 rows)
?..

Answer 4

If the format of the data you want to obtain is a set of characters follewd by a set of digits (i.e., GD123) you can use the regex:
[a-zA-Z0-9]+[0-9]

Answer 5

This captures every digit and letter which is in front of the digits:
([A-z]+\d+)