Deleting substrings throughout a column - postgresql

Question

I am trying to clean up throughout columns within a table to create a clear attribution/reference for reporting on my digital marketing campaigns. The goal is to keep one part of a string while deleting all others. All strings within my marketing campaigns have symbols separating each substring.
Attached are pictures of my current table and of the desired table.
I am essentially trying to only keep on part of the structure of a string and delete all other sub strings. I have already managed to do this successfully by applying the following formula given to be from a separate thread.
update adwords
set campaign = substring(campaign from '%-%-#"%#"' for '#')
where campaign like '%-%-%';
This worked perfectly, however, I do not fully understand why and have not found a clear answer thus far on this forum.
How would I apply this to future rows? Ad group and match type can be used for this purpose.
Many Thanks.

Answer 1

First thing: You do not modify source data. Do ETL instead, and transform it to a final stage. Do that periodically and thus taking care of new data.
You could just create a trigger which should work for all new data, but there are 2 caveats with that:
Failure will lead to missing data and you not being able to QA it.
If you modify the source data in an incorrect way by mistake, you cannot undo it unless you have a backup, and even then it's just too hard.
So instead look at ETL tools like Talend or Pentaho Kettle; create your own ETL scripts, or whatever. Use Jenkins to schedule all of this periodically and you're set.
Now, about the transformation itself.
for '#'
indicates that # will be an escape symbol, which means that #" will be treated as a regular quote in this case.
substring(campaign from '%-%-#"%#"' for '#')
thus, selects everything between the quotes in the pattern. % is a wildcard, same as used in LIKE comparisons. So everything in the last group will be returned. This can better be done with regular expressions
substring(campaign from '.*?-.*?-(.*)')
For the second column the regex would be ^(.*?)\s*\{
And for the third one - similar: ^(.*?)\s*\}
I would create the new table like this:
CREATE TABLE aw_final AS
SELECT
substring(campaign FROM '^\w{2}-\w+-(.*)$') AS campaign,
substring(ad_group FROM '^(\w+)\s*\{\w+\}$') AS ad_group,
substring(match_type FROM '^(\w+)\s*\}$') AS match_type
FROM adwords
WHERE campaign ~ '^\w{2}-\w+-(.*)$'
But if you must do an update, this would be how:
UPDATE adwords SET
campaign = substring(campaign FROM '^\w{2}-\w+-(.*)$'),
ad_group = substring(ad_group FROM '^(\w+)\s*\{\w+\}$'),
match_type = substring(match_type FROM '^(\w+)\s*\}$')
WHERE campaign ~ '^\w{2}-\w+-(.*)$'