SQL select in from a field containing comma separated keys - sql

Question

Is there a way I can construct a SQL statement that will help me retrieve active records based on status then references to oldids stored in another field?
Let's say I want to join the data below to another table. For ID=4, it is meant to imply that IDs 1,3 and 4 are combined and the surviving record is 4.
So when I want to join it with another table, how can I have scvid 104 be linked to transactions of IDs 1,3, and 4?
select *
from tbl
where scvid in (id, oldids)?
Sample data:
scvid id oldid status
------------------------------
101 1 NULL 0
102 2 NULL 1
103 3 NULL 0
104 4 [1,3] 1

Answer 1

You didn't mention your DB system. Here is the solution for SQL Server (TSQL). You can use it also in another RDBMS with minor changes
SELECT
t1.*, t2.scvid as NEWID
FROM
tbl t1
JOIN
tbl t2 ON
-- first case: if the record is main with [1,3] we link it to the the self
(t1.scvid = t2.scvid) AND (t2.oldid IS NOT NULL)
OR
-- second case: we bulid ",1,3," from "[1,3]"
-- then we get condition ",1,3," LIKE "%,id,%"
-- for the id = 1 and 3 it's TRUE
(REPLACE(REPLACE(t2.oldid,'[',','),']',',')
LIKE '%,'+CAST(t1.id as VARCHAR(100))+',%')
AND (t1.oldid IS NULL)
RESULT:
scvid id oldid status NEWID
101 1 NULL 0 104
103 3 NULL 0 104
104 4 [1,3] 1 104
This output new column NEWID for the old Id in this record so you can JOIN or use it in another way.

Answer 2

For Postgres you can do this by converting the comma separated list into an array.
Something like this:
Sample setup:
create table some_table (id integer);
insert into some_table values (4), (6), (8);
create table service (svcid integer, id integer, oldid text, status integer);
insert into service
values
(101, 1, NULL , 0),
(102, 2, NULL , 1),
(103, 3, NULL , 0),
(104, 4, '1,3', 1);
To get all rows from some_table where the id is either the id column of the service table or any of those in the oldid column you can use:
select *
from some_table st
join (
select svcid, id, oldid, status, string_to_array(s.oldid, ',')::int[]||id as all_ids
from service s
) s on st.id = any(s.all_ids)
This returns:
id | svcid | id | oldid | status | all_ids
---+-------+----+-------+--------+--------
4 | 104 | 4 | 1,3 | 1 | {1,3,4}

Answer 3

This works on SQL Server.
Since that LIKE syntax supports a negative character class as [^0-9].
select
old.scvid as old_scvid, old.id as old_id,
new.scvid as new_scvid, new.id as new_id, new.oldid as new_oldids
from tbl new
left join tbl old
on (old.status = 0 and new.oldid like concat('%[^0-9]',old.id,'[^0-9]%'))
where new.status = 1
and new.oldid is not null
To bad that the table doesn't have a "newid" field, instead of that "oldid" with a range.
That would make it a lot easier to join.