Get matching elements from an array comparison - postgresql

Question

I'm attempting to get matching elements regarding two arrays. I need to select them, so it essentially goes as follows
Contstraints:
Using Postgres 12, with no plugins.
String arrays, not int.
SQL I've come up with:
SELECT
elb.1,
elb.2,
esp.1,
esp.2
FROM
schema.table1 as esp
JOIN schema.table2 elb ON (elb.1 = esp.1)
WHERE
(esp.3 && ('{DHE:false, DHE:true, CAM:true}'::text[]))
Let's assume esp.3 ==
'{
BHE:false,
DHE:true,
CMD:true,
}'
What is the cleanest way to get that matching value DHE:true from these two arrays? I can't really alter the format of what i have here by much, so no functions etc.
I was really hoping to have something like:
SELECT
elb.1,
elb.2,
esp.1,
esp.2,
diff
FROM
schema.table1 as esp
JOIN schema.table2 elb ON (elb.1 = esp.1)
WHERE
select((esp.3 in any('{DHE:false, DHE:true, CAM:true}'::text[]))) as diff;
But i couldn't find any solution or variation on that. Any help is greatly appreciated!

Answer 1

any only returns true or false so it can stop looking once it matches.
You can use the technique from this answer to get the intersection of two text arrays.
SELECT
elb.1,
elb.2,
esp.1,
esp.2,
ARRAY(
SELECT *
FROM UNNEST( esp.3 )
WHERE UNNEST = ANY('{DHE:false, DHE:true, CAM:true}'::text[])
) as diff
FROM
schema.table1 as esp
JOIN schema.table2 elb ON (elb.1 = esp.1)
WHERE
(esp.3 && ('{DHE:false, DHE:true, CAM:true}'::text[]))
You can DRY it up with a CTE to first take the diff, then check it.
with esp as (
select
1,
2,
ARRAY(
SELECT *
FROM UNNEST( 3 )
WHERE UNNEST = ANY('{DHE:false, DHE:true, CAM:true}'::text[])
) as diff
from schema.table1
)
select
elb.1,
elb.2,
esp.1,
esp.2,
esp.diff
from
schema.table2 elb
join esp on (elb.1 = esp.1)
where cardinality(esp.diff) != 0;