select only required text in oracle without hardcoding the character position - oracle

Question

I have a column in database which stores data like follows
{0}="[DYD666020115982-ZO]",{1}="SomeText"
I want to get the 0th value ie DYD666020115982-ZO printed in output.
I have tried SUBSTR({0}="[DYD666020115982-ZO]",{1}="SomeText",7,18) which gives me output, but I wanted to know is there any other way without hard coding the position.

Answer 1

The oldfashioned substr + instr combination works good, works fast (res_1).
Regexp (res_2) along with trims (because of parenthesis) is another option:
SQL> with test (col) as
2 (select '{0}="[DYD666020115982-ZO]",{1}="SomeText"' from dual)
3 select substr(col, instr(col, '[') + 1,
4 instr(col, ']') - instr(col, '[') - 1
5 ) res_1,
6 --
7 rtrim(ltrim(regexp_substr(col, '\[.+\]'), '['), ']') res_2
8 from test;
RES_1 RES_2
------------------ ------------------
DYD666020115982-ZO DYD666020115982-ZO
SQL>

Answer 2

You can use REGEXP_SUBSTR to match the pattern (^|,)\{0\}="(([^"]|\\")*?)"(,|$):
Oracle Setup:
CREATE TABLE test_data ( id, list ) AS
SELECT 1, '{0}="[DYD666020115982-ZO]",{1}="SomeText"' FROM DUAL UNION ALL
SELECT 2, '{1}="SomeText with a \"Quote\"",{0}="[DYD666020115982-ZO]"' FROM DUAL UNION ALL
SELECT 3, '{1}="SomeText"' FROM DUAL UNION ALL
SELECT 4, '{0}="[DYD666020115982-ZO-2]",{1}="SomeText",{0}="[DYD666020115982-ZO-1]"' FROM DUAL UNION ALL
SELECT 5, '{1}="{0}=\"[DYD666020115982-ZO]\""' FROM DUAL;
Query:
SELECT REGEXP_SUBSTR( list, '(^|,)\{0\}="(([^"]|\\")*?)"(,|$)', 1, 1, NULL, 2 ) AS value
FROM test_data
Output:
| VALUE |
| :--------------------- |
| [DYD666020115982-ZO] |
| [DYD666020115982-ZO] |
| null |
| [DYD666020115982-ZO-2] |
| null |
or, if you want to string the leading and training characters then:
SELECT SUBSTR( value, 2, LENGTH( value ) - 2 ) AS value
FROM (
SELECT REGEXP_SUBSTR( list, '(^|,)\{0\}="(([^"]|\\")*?)"(,|$)', 1, 1, NULL, 2 ) AS value
FROM test_data
)
which outputs:
| VALUE |
| :------------------- |
| DYD666020115982-ZO |
| DYD666020115982-ZO |
| null |
| DYD666020115982-ZO-2 |
| null |
If you want to get all the values then you can use a recursive sub-query and REGEXP_SUBSTR:
Query:
WITH data ( id, list, key, value, idx, max_idx ) AS (
SELECT id,
list,
TO_NUMBER( REGEXP_SUBSTR( list, '\{(\d+)\}="(([^"]|\\")*?)"(,|$)', 1, 1, NULL, 1 ) ),
REGEXP_SUBSTR( list, '\{(\d+)\}="(([^"]|\\")*?)"(,|$)', 1, 1, NULL, 2 ),
1,
REGEXP_COUNT( list, '\{(\d+)\}="(([^"]|\\")*?)"(,|$)' )
FROM test_data
UNION ALL
SELECT id,
list,
TO_NUMBER( REGEXP_SUBSTR( list, '\{(\d+)\}="(([^"]|\\")*?)"(,|$)', 1, idx + 1, NULL, 1 ) ),
REGEXP_SUBSTR( list, '\{(\d+)\}="(([^"]|\\")*?)"(,|$)', 1, idx + 1, NULL, 2 ),
idx + 1,
max_idx
FROM data
WHERE idx < max_idx
)
SELECT id, key, value
FROM data
WHERE idx <= max_idx
ORDER BY id, key
Output:
ID | KEY | VALUE
-: | --: | :---------------------------
1 | 0 | [DYD666020115982-ZO]
1 | 1 | SomeText
2 | 0 | [DYD666020115982-ZO]
2 | 1 | SomeText with a \"Quote\"
3 | 1 | SomeText
4 | 0 | [DYD666020115982-ZO-2]
4 | 0 | [DYD666020115982-ZO-1]
4 | 1 | SomeText
5 | 1 | {0}=\"[DYD666020115982-ZO]\"
If you just want the values where the key is 0 then add AND key = 0 to the end of the query.
db<>fiddle here