Collecting into VARRAY inside SQL statement [duplicate]

Question

This question already has an answer here:

Is there any function in oracle similar to group_concat in mysql? [duplicate] (1 answer)

Closed 8 years ago.

I have the following SQL query :

SELECT ID, OC_YEAR FROM ACCOUNTS;

This query returns the following resultset:

       ID       |     OC_YEAR          
------------------------------------    
       10            2006
       10            2007
       10            2008
       11            2006
       11            2008

On the other hand I have a custom type

 create TYPE IDS AS VARRAY(10) OF NUMBER(5);

And finally I have a function that recieves 2 parameters of type IDS and NUMBER. Is there a way I can collect ID columns into an IDS variable grouping them under the OC_YEAR column and send these two arguments to my function. To make it clearer I need to group the resultset of the above query like this:

(10,11):2006
(10):2007
(10,11):2008

Not exactly but something similar to GROUP_CONCAT in MySQL.

Answer 1

Duplicate of this one:

If you have Oracle 10G:

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
                  ID
            FROM
                  ACCOUNTS
            WHERE
                  OC_YEAR = INPUT_VAL )
    LOOP
        RETURN_TEXT :=
               RETURN_TEXT
            || ','
            || X.ID;
    END LOOP;

    RETURN LTRIM ( RETURN_TEXT,
                ',' );
END;
/

So, you can do like:

SELECT
      GET_COMMA_SEPARATED_VALUE ( ID ),
      OC_YEAR
FROM
      ACCOUNTS;

If you have got oracle 11g, you can use listagg :

SELECT
      LISTAGG ( OC_YEAR,
              ', ' )
      WITHIN GROUP (ORDER BY ID),
      OC_YEAR
FROM
      ACCOUNTS
GROUP BY
      OC_YEAR;

Answer 2

Oracle 11.2 introduced function LISTAGG, which does the same like GROUP_CONCAT. If you don't have Oracle 11.2 available you have to encapsulate it in a function.