判断不为空函数

create table dept_info(
pk_name varchar(100),
dept01 varchar(100),
dept02 varchar(100)
)

insert into dept_info values('001','长租','小微'),('001','长租',''),('002','长租','')

select pk_name,case when d2 !='' then d2 else d1 end from
(select pk_name, max(dept01) as d1 ,max(dept02) as d2 from dept_info group by pk_name) T ;

select  pk_name,nvl(d2,d1) from
(select pk_name, max(dept01) as d1 ,max(dept02) as d2 from pbbase.dept_info group by pk_name) T ;

select  pk_name,ifnull(d2,d1)  from
(select pk_name, max(dept01) as d1 ,max(dept02) as d2 from pbbase.dept_info group by pk_name) T ;

select  pk_name,colesce(d2,d1)  from
(select pk_name, max(dept01) as d1 ,max(dept02) as d2 from pbbase.dept_info group by pk_name) T ;