How to transfer data with multiple conditions with pgsql? - regex

Question

I would like to create a trigger with I can check the uploaded data and I can insert into another table as well. In the initial table (capture) I have 15 columns, but I would like to transfer only 5 columns (ring_number, code, year, date, species, location) to another table (ring).
The ring table is a background table in which I am collecting the combinations of ring_number and code, more specifically one ring_number could be paired only with one code. There is one exception, when the code include "X", than it can be changed later, and in this case this code can be paired with more ring_number, and if originally belongs to the ring_number a code with "X" it can be changed later.
In the capture table, could be possible to upload the same combination of code and ring_number multiple times with a condition of a third column. But still the ring_number can be paired only with one code, with exceptions of codes included "X". The name of the conditional column is recapture. If recapture (boolean column type) is "true", then you can upload the combination of code and ring_number again. If it is "empty" or "no" you can upload only new combinations of code and ring_number. If somebody uploads old combinations then the following error message has to raise: this combination already exists, please check your data and if it is a recapture, then set the recapture column to yes.
Additionally: ring_number is a not null column, but code can be empty. And different ring_number can be paired with empty code than later can be paired with actual value.
I have several problems with my code:
1: I would like to define the exception to X with regex, and the X can be anywhere in the code. But can not manage the regex in a good way. It does just not work.
2: I write conditional checkpoint with recapture column and if I have an old combination this is work on the right way and say please set the recapture column to yes. But! If I set the recapture column to yes I get the same error message.
Could you help to solve these issues?
Here is my code:
Declare
a integer := 0;
b integer := 0;
c integer := 0;
d integer := 0;
Begin
IF new.code <> '' THEN
--Az 'a' means whether the given ring_number already exist in the database with a code, which is not empty
SELECT INTO a COUNT(*) FROM plover_captures PC WHERE PC.ring_number = new.ring_number AND PC.code <> new.code AND PC.code <> '' AND PC.code ~ '[X]{2}[\.]{1}[X]{2}[|]{1}[X]{2}[\.]{1}[X]{2}';
--Az 'b' means the given code already exist in the database with a ring_number
SELECT INTO b COUNT(*) FROM plover_captures PC WHERE PC.ring_number <> new.ring_number AND PC.code = new.code AND PC.code ~ '[X]{2}[\.]{1}[X]{2}[|]{1}[X]{2}[\.]{1}[X]{2}';
--Az 'c' how much times exist the given ring_number with the given code in the database
SELECT INTO c COUNT(*) FROM plover_captures PC WHERE PC.ring_number = new.ring_number AND PC.code = new.code AND PC.code ~ '[X]{2}[\.]{1}[X]{2}[|]{1}[X]{2}[\.]{1}[X]{2}';
--Az 'd' means the given combination already exist in ring table or not
SELECT INTO d COUNT(*) FROM plover_rings PC WHERE PC.ring_number = new.ring_number AND PC.code = new.code;
IF a > 0 THEN
raise exception 'This ring_number is already paired with another code before. %', new.ring_number;
END IF;
IF b > 0 THEN
raise exception 'This code is already paired with another ring_number before. %', new.code;
END IF;
IF c > 0 AND (new.rettrap IS null OR new.rettrap IS false) THEN
raise exception 'This ring_number and code pair is already in the database. So it is a rettrap but the rettrap attribute set to false or null. %, %, %', new.ring_number, new.code, new.rettrap;
END IF;
IF c = 0 AND new.rettrap IS true THEN
raise exception 'The rettrap attribute set to true but this ring_number and code pair is not in this database yet. %, %, %', new.ring_number, new.code, new.rettrap;
END IF;
IF c = 0 AND d = 0 THEN
Insert into plover_rings values(new.ring_number,new.code,new.species,new.location,new.year, new.date);
END IF;
END IF;
Return new;
End