使用 listagg 时不按表达式分组 function

Question

CREATE TABLE source_det (
    e_id       NUMBER(10),
    sys_name   VARCHAR2(20),
    ref_id     NUMBER(10),
    sys_other  VARCHAR2(30)
);

INSERT INTO source_det VALUES(11,'SOURCE',992,null);
INSERT INTO source_det VALUES(11,'SOURCE',637,null);
INSERT INTO source_det VALUES(11,'SOURCE',null,'Manual');
INSERT INTO source_det VALUES(11,'TARGET',637,null);

commit;

My Attempt:

SELECT e_id,
       LISTAGG(source, ';') source,
       LISTAGG(target, ';') target,
       source_other
  FROM (SELECT e_id,
               CASE
                 WHEN sys_name = 'SOURCE' THEN
                  ref_id
               END source,
               CASE
                 WHEN sys_name = 'TARGET' THEN
                  ref_id
               END target,
               CASE
                 WHEN sys_name = 'SOURCE' AND ref_id IS NULL THEN
                  sys_other
               END source_other
          FROM source_det
         GROUP BY e_id);

From the above set of data I need only a single row to be returned from the SELECT query but I am getting null values instead along with the required values. If sys_name is SOURCE then the result should be ref_id . If there is more than one record then it should be spilitted by delimiter; If sys_name is TARGET then result should be ref_id If sys_name is SOURCE AND ref_id is null then it should give sys_other as a result. But from my query I am not getting a single row instead getting 4 rows. But ideally, I need only one row with e_id 11 And most important is in place of null values it could be possible that there would be () present in place of null. So, need to exclude this as well. After getting the desired result then we can use DECODE(ref_id,'()',null) like this.

Expected result:

e_id	source	target	source_other
11	992;637	637	Manual

Tool used: SQL Developer (18c)

Answer 1

You don't need a subquery, just use like the following one below

SELECT e_id,
       LISTAGG(CASE
                 WHEN sys_name = 'SOURCE' THEN
                  ref_id
               END,
               ';') WITHIN GROUP(ORDER BY ref_id DESC) AS source,
       LISTAGG(CASE
                 WHEN sys_name = 'TARGET' THEN
                  ref_id
               END,
               ';') WITHIN GROUP(ORDER BY ref_id DESC) AS target,
       LISTAGG(CASE
                 WHEN sys_name = 'SOURCE' AND ref_id IS NULL THEN
                  DECODE(sys_other,'()','',sys_other)
               END,
               ';') WITHIN GROUP(ORDER BY 0) AS source_other
  FROM source_det
 GROUP BY e_id

where missing WITHIN GROUP (ORDER BY..) should follow LISTAGG(...) expression

Demo