Selecting one out of many strings with concatenation in Redshift - sql

Question

I have to match the following URLs by writing a query in Amazon Redshift:
<some url>/www.abc.com/a/<more url>
<some url>/www.abc.com/b/<more url>
<some url>/www.abc.com/c/<more url>
<some url>/www.abc.com/d/<more url>
Here, obviously the "/www.abc.com/" is constant, but the text after '/' can change. It can take one of the many values that I have a list of (a,b,c,d in this case). How do I match this part that comes immediately after "/www.abc.com/"?
I can think of the following:
select text,
case
when text ilike '%/www.abc.com/' || <what should go here?> || '/%' then 'URLType1'
when <some other condition> then 'URLType2'
end as URLType
from table
I have to maintain the CASE structure.
Any help would be much appreciated.

Answer 1

THe options are:
1) put the list of values into a subquery and then join to this list like this:
with
value_list as (
select 'a' as val union select 'b' union select 'c' union select 'd'
)
select text
from table
join value_list
on text ilike '%/www.abc.com/' || val || '/%'
2) use OR:
select text,
case
when text ilike '%/www.abc.com/a/%'
or text ilike '%/www.abc.com/b/%'
or text ilike '%/www.abc.com/c/%'
or text ilike '%/www.abc.com/d/%'
then 'URLType1'
when <some other condition>
then 'URLType2'
end as URLType
from table
3) Write a Python UDF that takes the url and the list and returns true or false like this:
CREATE OR REPLACE FUNCTION multi_ilike(str varchar(max),arr varchar(max))
RETURNS boolean
STABLE AS $$
if str==None or arr==None:
return None
arr = arr.split(',')
str = str.lower()
for i in arr:
if i.lower() in str:
return True
return False
$$ LANGUAGE plpythonu;
select multi_ilike('<some url>/www.abc.com/a/<more url>','/www.abc.com/a/,/www.abc.com/b/,/www.abc.com/c/,/www.abc.com/d/'); -- returns true
select multi_ilike('<some url>/www.abc.com/F/<more url>','/www.abc.com/a/,/www.abc.com/b/,/www.abc.com/c/,/www.abc.com/d/'); -- returns false