62

My inputs are in this way.

col1   col2
1      a
1      b
2      c
2      d
2      e

O/p: Should Be like

col1    col2
1       a,b
2       c,d,e

I want a query that can be fired at DB level. I've tried various ways, but wasn't able to make this out...

cacti5
  • 2,006
  • 2
  • 25
  • 33
Prashanth
  • 1,294
  • 3
  • 13
  • 30
  • Do you want the query to work both in Oracle and in MySQL? – YasirA May 27 '13 at 10:26
  • 4
    possible duplicate of [this](http://stackoverflow.com/questions/4686543/sql-to-concatenate-column-values-from-multiple-rows) or [this](http://stackoverflow.com/questions/1120706/is-there-an-oracle-sql-query-that-aggregates-multiple-rows-into-one-row) or [this](http://stackoverflow.com/questions/12145379/how-to-retrieve-two-columns-data-in-a-b-format-in-oracle) or [this](http://stackoverflow.com/questions/5822700/building-a-comma-separated-list-of-values-in-an-oracle-sql-statement) or ... – A.B.Cade May 28 '13 at 06:38
  • 1
    ...or [this](http://stackoverflow.com/questions/43256810/how-to-select-multiple-rows-in-a-single-row-with-condition-oracle) – Bohemian Dec 04 '18 at 01:04

1 Answers1

106

11g and higher: Use listagg:

SELECT 
    col1,
    LISTAGG(col2, ', ') WITHIN GROUP (ORDER BY col2) "names"
FROM table_x
GROUP BY col1

10g and lower: One method is to use a function:

CREATE OR REPLACE FUNCTION get_comma_separated_value (input_val  in  number)
  RETURN VARCHAR2
IS
  return_text  VARCHAR2(10000) := NULL;
BEGIN
  FOR x IN (SELECT col2 FROM table_name WHERE col1 = input_val) LOOP
    return_text := return_text || ',' || x.col2 ;
  END LOOP;
  RETURN LTRIM(return_text, ',');
END;
/

To use the function:

select col1, get_comma_separated_value(col1) from table_name

Note: There is an (unsupported) function WM_CONCAT available on certain older versions of Oracle, which might help you out - see here for details.

In MySQL:

SELECT col1, GROUP_CONCAT(col2) FROM table_name GROUP BY col1
zb226
  • 9,586
  • 6
  • 49
  • 79
hsuk
  • 6,770
  • 13
  • 50
  • 80
  • 3
    LISTAGG will throw a "ORA-01489: result of string concatenation is too long" if result exceeds VARCHAR2 limits. See http://stackoverflow.com/a/29008456/848072 for custom aggregate function – albfan Feb 24 '17 at 08:54