Select Query to check both or either or condition

Question

I\'m using postgresql 9.1 and wish to select a single record from table. Details are as below :

table name : muser

fields present in table : userid,username,fir

Answer 1

When I'm dealing with filter where the value can be any including null I'll try add coalesce()

SELECT userid, mailid, phonenumber 
FROM muser 
WHERE coalesce(phonenumber,'no data') = coalesce(?,'no data') 
OR coalesce(mailid,'no data') = coalesce(?, 'no data');

Answer 2

Assuming that when you mean "not present", mailid or phonenumber will be NULL in database,

SELECT userid, mailid, phonenumber 
FROM muser 
WHERE (phonenumber = ? AND (mailid IS NULL OR mailid = ''))
OR ((phonenumber IS NULL OR phonenumber = '') AND mailid = ?)
OR (phonenumber = ? AND mailid = ?)