select distinct agent, count(customer) as total_customer,
(select count(january_1) from salestable where january_1!=0 group by agent) as sales_customer
from salestable
where customer_type = "urban"
group by agent
order by agent asc

more than one row returned by a subquery used as an expression

more than one row returned by a subquery used as an expression

select agent,
       count(customer) as total_customer,
       count(case when january_1 <> 0 then 1 end)  as sales_customer
from salestable
where customer_type = "urban"
group by agent
order by agent asc