MySQL IFNULL question

I have a query which contains a subquery which is something like this

IFNULL(开发者_如何学JAVA(SELECT id FROM mytable WHERE id = 1), 'No')

It works OK, but I would like to return the string 'Yes' on success rather than the actual id of the row.

Is there any way to override the value it returns?

Thanks.

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IFNULL((SELECT 'Yes' FROM mytable WHERE id = 1), 'No')

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Little Advance example of IFNULL:

Problem: How to get the home phone number if office phone number is not available ?

Solution:

SELECT IFNULL(office_phone_no,home_phone_no) as contact_number
FROM employee_table e
where e.username = 'sumoanand';