REGEXP_SUBSTR where in condition - sql

Question

I have this data in a table
procedure1/loc1/p1
proc2/loc1/p2/c1
proc1/loc2/p2/c2
procedure3/loc1/p1
procedure4/loc3/p1
I want a query to select specific proc, like proc1 and procedure4 , like wouldnt work so
the ouptput should be like this
proc1/loc2/p2/c2
procedure4/loc3/p1
I tried to use REGEXP_SUBSTR, but how include the list of the procedure that i want ?
--this is wrong
select * from tab1 where REGEXP_SUBSTR(col1,
'[^/]+', 1, 1) in ('proc1','procedure4')

Answer 1

you could check, if the length returned by REGEXP_SUBSTR is greater than 0
select *
from (select 'procedure1/loc1/p1' a from dual union
select 'proc2/loc1/p2/c1' from dual union
select 'proc1/loc2/p2/c2' from dual union
select 'procedure3/loc1/p1' from dual union
select 'procedure4/loc3/p1' from dual) t
where length(regexp_substr(t.a, 'procedure4|proc1')) > 0
alternativly you could use REGEXP_LIKE, which does simply return a boolean and in my oppinion would fit better here.
select *
from (select 'procedure1/loc1/p1' a from dual union
select 'proc2/loc1/p2/c1' from dual union
select 'proc1/loc2/p2/c2' from dual union
select 'procedure3/loc1/p1' from dual union
select 'procedure4/loc3/p1' from dual) t
where regexp_like(t.a, 'procedure4|proc1')
O/P
proc1/loc2/p2/c2
procedure4/loc3/p1
if you would want to get the values from a table you could generate the regex dynamicly with the listagg function provided by oracle. What happens now is, that each possible value, that could occure is getting concatinated with an |, which does represent an or in regex. Due to this you you're not in need for an in, because your regex will have each possible value seperated by an or
select *
from (select 'procedure1/loc1/p1' a from dual union
select 'proc2/loc1/p2/c1' from dual union
select 'proc1/loc2/p2/c2' from dual union
select 'procedure3/loc1/p1' from dual union
select 'procedure4/loc3/p1' from dual) t
where regexp_like(t.a, (select listagg(regexp.b, '|') WITHIN GROUP (ORDER BY regexp.b) regex
from (select 'procedure4' b from dual union
select 'proc1' from dual) regexp))
O/P of the subquery used for the regex would be proc1|procedure4, which would be the regexp needed as seen in the previous example

Answer 2

You don't need to use regular expressions to do that. You just could use ordinary SUBSTR and INSTR to get the substring from the beginning to the first /:
WITH your_table AS (
SELECT 'procedure1/loc1/p1' procedure_name FROM dual
UNION
SELECT 'proc2/loc1/p2/c1' procedure_name FROM dual
UNION
SELECT 'proc1/loc2/p2/c2' procedure_name FROM dual
UNION
SELECT 'procedure3/loc1/p1' procedure_name FROM dual
UNION
SELECT 'procedure4/loc3/p1' procedure_name FROM dual
)
SELECT *
FROM your_table
WHERE SUBSTR(procedure_name,1,INSTR(procedure_name,'/')-1) IN ('proc1','procedure4');
However, if you want to learn to use regular expressions in Oracle. You could use REGEXP_SUBSTR like this:
WITH your_table AS (
SELECT 'procedure1/loc1/p1' procedure_name FROM dual
UNION
SELECT 'proc2/loc1/p2/c1' procedure_name FROM dual
UNION
SELECT 'proc1/loc2/p2/c2' procedure_name FROM dual
UNION
SELECT 'procedure3/loc1/p1' procedure_name FROM dual
UNION
SELECT 'procedure4/loc3/p1' procedure_name FROM dual
)
SELECT *
FROM your_table
WHERE REGEXP_SUBSTR(procedure_name,'^(.+?)/',1,1,'i',1) IN ('proc1','procedure4');
The last parameter tells Oracle to return the match for the pattern between ().
As already mentioned, you also could use REGEXP_LIKE:
WITH your_table AS (
SELECT 'procedure1/loc1/p1' procedure_name FROM dual
UNION
SELECT 'proc2/loc1/p2/c1' procedure_name FROM dual
UNION
SELECT 'proc1/loc2/p2/c2' procedure_name FROM dual
UNION
SELECT 'procedure3/loc1/p1' procedure_name FROM dual
UNION
SELECT 'procedure4/loc3/p1' procedure_name FROM dual
)
SELECT *
FROM your_table
WHERE REGEXP_LIKE(procedure_name,'^(proc1|procedure4)/');

Answer 3

If the procedures you are interesetd in are in a different table, one way could be the following:
Setup:
CREATE TABLE your_table (col) AS
(SELECT 'procedure1/loc1/p1' FROM DUAL UNION ALL
SELECT 'proc2/loc1/p2/c1' FROM DUAL UNION ALL
SELECT 'proc1/loc2/p2/c2' FROM DUAL UNION ALL
SELECT 'procedure3/loc1/p1' FROM DUAL UNION ALL
SELECT 'procedure4/loc3/p1' FROM DUAL
)
CREATE TABLE procedures (name) AS
(SELECT 'proc1' FROM DUAL UNION ALL
SELECT 'procedure4' FROM DUAL
)
You can try this, with no need for regular expressions:
SELECT *
FROM your_table
INNER JOIN procedures
ON (INSTR(col, name) != 0)