Comparing two comma delimited strings - sql

Question

I have 2 strings str1: 'abc,def,ghi' and str2: 'tyu,abc,fgh'.
I want to compare these two strings using the delimiter ,. Now since the 2 strings have abc it should return true. I want a function in Oracle SQL which can perform this operation.

Answer 1

Looks complicated but it is just a couple of helper functions to split a list into separate values (to be contained into a table type) and then a very simple function to test the intersection of two collections.
Oracle Setup:
CREATE TYPE VARCHAR2s_Table AS TABLE OF VARCHAR2(4000);
CREATE FUNCTION regexp_escape(
expression VARCHAR2
) RETURN VARCHAR2 DETERMINISTIC
AS
BEGIN
RETURN REGEXP_REPLACE( expression, '([$^[()+*?{\|])', '\\\1', 1, 0, 'c' );
END;
/
CREATE FUNCTION splitList(
list VARCHAR2,
delim VARCHAR2 := ','
) RETURN VARCHAR2s_Table DETERMINISTIC
AS
pattern VARCHAR2(256);
len BINARY_INTEGER;
t_items VARCHAR2s_Table := VARCHAR2s_Table();
BEGIN
IF list IS NULL THEN
NULL;
ELSIF delim IS NULL THEN
t_items.EXTEND( LENGTH( list ) );
FOR i IN 1 .. LENGTH( list ) LOOP
t_items(i) := SUBSTR( list, i, 1 );
END LOOP;
ELSE
pattern := '(.*?)($|' || REGEXP_ESCAPE( delim ) || ')';
len := REGEXP_COUNT( list, pattern ) - 1;
t_items.EXTEND( len );
IF len = 1 THEN
t_items(1) := list;
ELSE
FOR i IN 1 .. len LOOP
t_items(i) := REGEXP_SUBSTR( list, pattern, 1, i, NULL, 1 );
END LOOP;
END IF;
END IF;
RETURN t_items;
END;
/
CREATE FUNCTION check_list_intersect(
list1 VARCHAR2,
list2 VARCHAR2
) RETURN NUMBER DETERMINISTIC
AS
BEGIN
IF splitList( list1 ) MULTISET INTERSECT splitList( list2 ) IS EMPTY THEN
RETURN 0;
ELSE
RETURN 1;
END IF;
END;
/
Query 1:
SELECT check_list_intersect( 'abc,def,ghi', 'abc' ) AS matches
FROM DUAL;
Results:
MATCHES
---------
1
Query 2:
SELECT check_list_intersect( 'abc,def,ghi', 'abcd' ) AS matches
FROM DUAL;
Results:
MATCHES
---------
0

Answer 2

The below will make the trick.
with temp as (
select 1 strid, 'abc,def,ghi' Error from dual
union all
select 2, 'tyu,abc,fgh' from dual
)
select str
from (
SELECT strid, trim(regexp_substr(str, '[^,]+', 1, level)) str
FROM (SELECT strid, Error str FROM temp) t
CONNECT BY instr(str, ',', 1, level - 1) > 0
)
group by str
having count(distinct strid) > 1;

Answer 3

Warning: This answer is not fully correct. (See the comments.)
Starting from dcieslak answer(csv split with regexp), a variation of the subject would be:
create or replace function check_string_intersec(str1 varchar2, str2 varchar2) return number
is
begin
for k in (SELECT trim(regexp_substr(str1, '[^,]+', 1, level)) item
FROM dual
CONNECT BY instr(str1, ',', 1, level - 1) > 0
)
loop
if instr(str2, k.item,1) > 0 then return 1; end if;
end loop;
return 0;
end;
This splits first string and search for every item in the second string.