postgres case ERROR：用作表达式的子查询返回的多行

Question

with temp as(
select a.fk_audit_inserimento
from mtd.t_mtd_all_dt_elab_etl a,mtd.t_mtd_all_dt_anag_etl b
where a.fk_etl_caricamento=b.pk_etl_caricamento
and b.sds_livello='DMT' and b.sds_nome_etl='JOB_DM_MOBILE_CODE'
order by 1 desc
limit 2
)

select
case 
when
(select count(*) from temp)=1
then
(select 19000101000000, 
union
select fk_audit_inserimento from temp)
when
(select count(*) from temp)=2
then (select fk_audit_inserimento from temp)
end

我想要那个 If count (*) of TEMP =1然后我想要两条记录19000101000000和select fk_audit_inserimento from temp; If count(*) of TEMP =2然后我想要select fk_audit_inserimento from temp.

但我有

  

错误：多行。

我如何解决它？

感谢

Answer 1

尝试以下几点：

SELECT 19000101000000
WHERE (SELECT count(*) FROM temp)=1
UNION
SELECT fk_audit_inserimento FROM temp ;