ORACLE SQL | If a column contains a value, then it will exclude a different value from the same column - sql

Question

I have this query that returns the data below it
select LISTAGG(d.DOCUMENT_TYPE_CD, ',') WITHIN GROUP (ORDER BY D.DOCUMENT_TYPE_CD) as value
from test_table d;
VALUE
---------
CI,ECI,POA
now I'm trying to add a condition whenever 'ECI' value is present, it should exclude 'CI' in the result like this one below
VALUE
---------
ECI,POA
I tried using case statement in where condition it prompted an error
select LISTAGG(d.DOCUMENT_TYPE_CD, ',')
WITHIN GROUP (ORDER BY D.DOCUMENT_TYPE_CD) as value
from test_table d
where CASE d.DOCUMENT_TYPE_CD
WHEN 'ECI' THEN d.DOCUMENT_TYPE_CD <> 'CI'
END;
ORA-00905: missing keyword
00905. 00000 - "missing keyword"
*Cause:
*Action:
Error at Line: 7 Column: 36
is there any other way I could resolve this?

Answer 1

See if this helps; read comments within code.
SQL> with
2 test (id, document_type_cd) as
3 -- sample data
4 (select 1, 'ECI' from dual union all
5 select 1, 'CI' from dual union all
6 select 1, 'POA' from dual union all
7 --
8 select 2, 'CI' from dual union all
9 select 2, 'POA' from dual union all
10 --
11 select 3, 'XYZ' from dual union all
12 select 3, 'ABC' from dual
13 ),
14 temp as
15 -- see whether CI and ECI exist per each ID
16 (select id,
17 sum(case when document_type_cd = 'CI' then 1 else 0 end) sum_ci,
18 sum(case when document_type_cd = 'ECI' then 1 else 0 end) sum_eci
19 from test
20 group by id
21 ),
22 excl as
23 -- exclude CI rows if ECI exist for that ID
24 (select a.id,
25 a.document_type_cd
26 from test a join temp b on a.id = b.id
27 where a.document_type_cd <> case when b.sum_ci > 0 and b.sum_eci > 0 then 'CI'
28 else '-1'
29 end
30 )
31 -- finally:
32 select e.id,
33 listagg(e.document_type_cd, ',') within group (order by e.document_type_cd) result
34 from excl e
35 group by e.id;
ID RESULT
---------- --------------------
1 ECI,POA
2 CI,POA
3 ABC,XYZ
SQL>

Answer 2

Something like this:
select LISTAGG(d.DOCUMENT_TYPE_CD, ',')
WITHIN GROUP (ORDER BY D.DOCUMENT_TYPE_CD) as value
from test_table d,
(select sum (case when DOCUMENT_TYPE_CD = 'CI' then 1 else 0 end) C
from test_table) A
where d.DOCUMENT_TYPE_CD <> case when A.c > 0 then 'CI' when A.c = 0 then ' ' end;
DEMO

Answer 3

You may identify the presence of both the values with two conditional aggregations in the same group by and then replace CI inside the result of listagg in one pass.
with a(id, cd) as (
select 1, 'ABC' from dual union all
select 1, 'ECI' from dual union all
select 1, 'CI' from dual union all
select 1, 'POA' from dual union all
select 2, 'XYZ' from dual union all
select 2, 'ECI' from dual union all
select 2, 'CI' from dual union all
select 2, 'POA' from dual union all
select 3, 'CI' from dual union all
select 3, 'POA' from dual union all
select 4, 'ABC' from dual union all
select 4, 'DEF' from dual
)
select
id,
ltrim(
/*Added comma in case CI will be at the beginning*/
replace(
',' || listagg(cd, ',') within group (order by cd asc),
decode(
/*If both are present, then replace CI. If not, then do not replace anything*/
max(decode(cd, 'CI', 1))*max(decode(cd, 'ECI', 1)),
1,
',CI,'
),
','
),
','
) as res
from a
group by id
ID | RES
-: | :----------
1 | ABC,ECI,POA
2 | ECI,POA,XYZ
3 | CI,POA
4 | ABC,DEF
db<>fiddle here

Answer 4

Instead of using GROUP BY, you can also use windowing (aka analytic) functions to check the presence of ECI per group (test data shamelessly stolen from #littlefoot):
with
test (id, document_type_cd) as
-- sample data
(select 1, 'ECI' from dual union all
select 1, 'CI' from dual union all
select 1, 'POA' from dual union all
--
select 2, 'CI' from dual union all
select 2, 'POA' from dual union all
--
select 3, 'XYZ' from dual union all
select 3, 'ABC' from dual
),
temp as
(select id,
document_type_cd,
sum(case when document_type_cd = 'ECI' then 1 else 0 end) over (partition by id) as sum_eci
from test
)
select a.id,
listagg(a.document_type_cd, ',') within group (order by a.document_type_cd) result
from temp a
where a.document_type_cd != 'CI' or sum_eci = 0
group by a.id;