Question

The following sql snippet below is a subselect of a parent sql.

Is there a way to say, “If customer doesn’t exist I want to run a different sql”?

select orderdate, 
    (select contactname from customers where customerID = 'ALFKI' or select 'No Customer') as contactname

from orders

I know this can be solved with a join but mainly interested of the possibility?

Answer 1

The thing that you’re trying to do here is called LEFT JOIN with ISNULL:

select OrderDate, isnull(c.FullName, 'No customer') CustomerName
from Orders o
left join Customers c on o.CustomerId = c.CustomerId