convert string into rows with SQL - sql

Question

I have a string, like:
'one,two,three'
and I want to convert it in rows and use it into IN clause in an SQL:
one
two
three
I tried something like :
SELECT column_value
FROM XMLTable('"one","two","three"');
and it worked fine but in a join condition it fails.
SELECT 1
FROM dual
WHERE 'one' IN (SELECT column_value
FROM XMLTable('"one","two","three"'));
it gaves me the error:
ORA-00932: inconsistent datatypes: expected - got CHAR
00932. 00000 - "inconsistent datatypes: expected %s got %s"
Can anyone help me on this, please?
NOTE: I would like not use PLSQL

Answer 1

What you need is nothing but just casting a CLOB value to a [VAR]CHAR[2] data type such as
SELECT 1
FROM dual
WHERE 'one' IN (SELECT CAST(column_value AS VARCHAR2(20))
FROM XMLTable('"one","two","three"'))
1
---
1
in order to make it comparable with a literal(such as 'one').
Moreover, CAST might be replaceable with XMLCast as well.

Answer 2

You do not need XML to split the string and can use simple (fast) string functions:
WITH data (value) AS (
SELECT 'one,two,three' FROM DUAL
),
bounds (value, spos, epos) AS (
SELECT value, 1, INSTR(value, ',', 1)
FROM data
UNION ALL
SELECT value, epos + 1, INSTR(value, ',', epos + 1)
FROM bounds
WHERE epos > 0
)
SEARCH DEPTH FIRST BY value SET order_id
SELECT CASE epos
WHEN 0
THEN SUBSTR(value, spos)
ELSE SUBSTR(value, spos, epos-spos)
END as item
FROM bounds;
Which outputs:
ITEM
one
two
three
However
In your case you have an XY-problem and you DO NOT NEED to split the string as you can use LIKE to match the search string against a sub-string of your list:
SELECT 1
FROM dual
WHERE ',' || :your_list || ',' LIKE '%,' || :search_value || ',%';
or with hardcoded strings:
SELECT 1
FROM dual
WHERE ',' || 'one,two,three' || ',' LIKE '%,' || 'one' || ',%';
db<>fiddle here

Answer 3

Query that raised an error - if rewritten to this - works:
SQL> select 1
2 from dual
3 where 'one' in (select regexp_substr('one,two,three', '[^,]+', 1, level)
4 from dual
5 connect by level <= regexp_count('one,two,three', ',') + 1
6 );
1
----------
1
SQL>
Subquery (that uses regexp_substr) splits a comma-separated list of values ('one,two,three') into rows.
Alternatively, if you use Oracle Apex (or have it installed in your database), you can simplify it by utilizing apex_string.split:
SQL> select 1
2 from dual
3 where 'one' in (select * from apex_string.split('one,two,three', ','));
1
----------
1
SQL>

Answer 4

You could use REGEXP_COUNT to find your word in the list.
This would be faster than converting
But read this canonical thread Is storing a delimited list in a database column really that bad?
SELECT
CASE WHEN REGEXP_COUNT('one,two,three', '^([^,]+,)*one(,[^,]+)*$', 1, 'i') > 0
THEN 1 ELSE 0
END as cnt
FROM DUAL;
| CNT |
| --: |
| 1 |
db<>fiddle here