impala mysql coalesce 里面子查询

mysql支持

select coalesce(

(select 1 from tableA where customer_id = '1234' limit 1),

(select 1 from tableB where customer_id = '5678' limit 1),

0

)

常用于看一个客户是否存在于A表或B表中。

但是impala并不支持这样的语法，也尝试了去掉括号仍然报错，错误本质应该还是impala不支持

形如：

select (select df_days from t_installments where inst_num = 1 and loan_id = a.loan_id) AS fpd

from t_installments a

【AnalysisException: Subqueries are not supported in the select list.

】

子查询不支持在select list中，子查询可以在in list中