output of replace SQL as a where clause in another SQL - sql

Question

Sorry for the rubbish title. I could quite articulate my problem in a few words.
I have an SQL that gives a list of ids separate by a pipe (|). I want to pass these ids into another sql as a where clause. I can use replace to convert the values from pipe separate into comma separated.
As an example the list of IDs might be
1|2|3|4
and using replace I get
1,2,3,4
select replace(value, '|', ',') from my_table;
If I try and pass this into another SQL where I want to look up these IDs I get an error
ORA-01722: invalid number
select * from my_table2 where id in (
select replace(value, '|', ',') from my_table);
Now I presume I need to cast the output to a number but I dont want to cast the entire string to a number just hte numeric values within it.
How can I do this easily?
Thanks

Answer 1

This is a complicated expression, but you can do it with like and exists:
select *
from my_table2
where exists (select 1
from my_table t1
where '|' || value || '|' like '%|' || id || '|%'
);
However, you have a fundamental problem with the data structure in my_table. You should not be storing lists of anything -- and especially integer ids -- in a string. The proper SQL approach is to use a junction table, with one row per id. Oracle has other data structures such as nested tables, which can help with this.

Answer 2

There may be two cases: good and bad.
Bad case is your pipe-separated string is stored somewhere in the database and you cannot change this design to something meaningful. If so, you'll need to use like operator, something like this:
select t2.*
from my_table2 t2, my_table t
where '|' || t1.value || '|' like '%|' || t2.id || '|%'
Good case is this pipelining isn't persistent and made by first SQL. If so, you should just remove garbage. Remove pipelining, remove listing into one row. Make inner SQL return resultset of IDs required, one per row, and use something like
select t2.*
from my_table2 t2
where t2.id in (select id from ...)
Additional case is if this list is a parameter value transferred from client. Some developers use this approach to make filters etc. If so, you should change client for transferring something better, say, table of numbers. SQL would be like
select t2.*
from my_table2 t2
where t2.id in (select column_value from table(cast :param as NumberTable))

Answer 3

We do it the following way. We have one function that splits string and returns table. The code is TSQL, but i think you can easily change it to ORACLE SQL
CREATE FUNCTION [dbo].[fStringToTable]
(
#List NVARCHAR(MAX) ,
#Splitter NVARCHAR(MAX)
)
RETURNS #ParsedList TABLE ( ID INT )
AS
BEGIN
DECLARE #ID NVARCHAR(MAX) ,
#Pos INT ,
#sqlstat NVARCHAR(MAX)
DECLARE #tbl TABLE ( ID INT )
SET #List = LTRIM(RTRIM(#List)) + #Splitter
SET #Pos = CHARINDEX(',', #List, 1)
IF REPLACE(#List, #Splitter, '') <> ''
BEGIN
WHILE #Pos > 0
BEGIN
SET #ID = LTRIM(RTRIM(LEFT(#List, #Pos - 1)))
IF #ID <> ''
BEGIN
INSERT INTO #tbl
( ID )
SELECT ( #ID )
END
SET #List = RIGHT(#List, LEN(#List) - #Pos)
SET #Pos = CHARINDEX(#Splitter, #List, 1)
END
END
INSERT INTO #ParsedList
SELECT ID
FROM #tbl
GROUP BY ID
RETURN
END
And your select will be
select * from my_table2 where id in (
SELECT ID FROM [dbo].[fStringToTable]('1,2', ','));
See this http://www.adp-gmbh.ch/ora/plsql/coll/return_table.html