SQL: If-condition when result does not exist? [closed]

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably an开发者_如何学Cswered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 10 years ago.

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?

---

example

IF NOT EXISTS (select * from customers where customerID = 'ALFKI')
BEGIN
    SELECT '1'
END
ELSE
BEGIN
    SELECT '2'
END

---

Please disregard this question. I should have been weary asking because the question sounded even confusing for me.

Turns out I was in the wrong place when the answer was elsewhere. The answer was solved with precedence parenthesis just like that. Sorry for the confusion.

rod.

---

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