How to remove duplicated values from attribute - sql

Question

I have a column with duplicated values in single cell, please tell me how can i remove duplicated values using sql or pl/sql only.
| Test
-+--------------------------------------------------------------------
| 999999999(10145) 999999999(10145) 999999999(10145) 999999999(10145)
|--------------------------------------------------------------------
| 113307425(2) 310122174(2) 310122174(2) 113307425(2)

Answer 1

Use a regular expression with a back-reference to match the repeating terms:
Oracle Setup:
CREATE TABLE test_data ( value ) AS
SELECT '9999999(12345) 9999999(12345) 9999999(12345) 9999999(12345)' FROM DUAL;
Query:
SELECT REGEXP_REPLACE( value, '([^ ]+)( \1)+', '\1' ) AS replaced_value
FROM test_data
Output:
| REPLACED_VALUE |
| :------------- |
| 9999999(12345) |
db<>fiddle here
Updated: For new data in the 6th edit:
CREATE TABLE test_data ( value ) AS
SELECT '9999999(12345) 9999999(12345) 9999999(12345) 9999999(12345)' FROM DUAL UNION ALL
SELECT '113307425(2) 310122174(2) 310122174(2) 113307425(2)' FROM DUAL;
Query:
Use a recursive sub-query factoring clause to find the terms in the string and then use DISTINCT to remove the duplicates and the LISTAGG to concatenate them back into a single string.
WITH bounds ( id, value, start_pos, end_pos ) AS (
SELECT ROWID,
value,
1,
INSTR( value, ' ', 1 )
FROM test_data
UNION ALL
SELECT id,
value,
end_pos + 1,
INSTR( value, ' ', end_pos + 1 )
FROM bounds
WHERE end_pos > 0
),
strings ( id, value ) AS (
SELECT DISTINCT
id,
CASE end_pos
WHEN 0
THEN SUBSTR( value, start_pos )
ELSE SUBSTR( value, start_pos, end_pos - start_pos )
END
FROM bounds
)
SELECT LISTAGG( value, ' ' ) WITHIN GROUP ( ORDER BY value ) AS unique_values
FROM strings
GROUP BY id
Output:
| UNIQUE_VALUES |
| :------------------------ |
| 9999999(12345) |
| 113307425(2) 310122174(2) |
db<>fiddle here

Answer 2

Oracle allows for recursive subquery factoring that can be harnessed to apply regexp based substitutions repeatedly:
CREATE TABLE test_data ( value ) AS
SELECT '9999999(12345) 9999999(12345) 9999999(12345) 9999999(12345)' FROM DUAL;
WITH rep(n,s,n_maxrep) AS (
SELECT 1
, value
, 1 + LENGTH(REGEXP_REPLACE(value, '[^ ]', ''))
FROM test_data
UNION ALL
SELECT n+1
, REGEXP_REPLACE ( s, '([^ ]+)(( [^ ]+)*)( \1)+', '\1\2' )
, n_maxrep
FROM rep
WHERE n <= n_maxrep
)
SELECT s FROM rep WHERE n = n_maxrep;
Explanation
The query repeatedly applies the same basic regex-based replacement of a single verb duplicate. to the original column. A 'verb' in this context is the maximal sequence of consecutive non-space chars. The duplicates may be next to each other or be separated by other verbs.
The maximum possible number of such replacements is known beforehand: n-1 for n verbs, when all verbs are identical. This is equivalent to the number of occurrences of the separating character in the original value.
Everything else is syntactic sugar. Oracle builds the nested chain of subqueries on its own.
Note that the limit n_maxrep is actually 1 + <number_of_separator_occurrences>. This is necessary as the base case ( n=1 ) does no replacement.