是否有更簡單的方法來編寫此查詢？

Question

我在MySQL查詢，做一些認證檢查，但它是相當長的。我想知道是否會有另一種方法來縮短/簡化它，但實際上所有的子句都是必需的。

select nickname from nicknames where nickname = '$nick' and password = '$md5pass' 
union 
select '$nick' as nickname from nicknames AS t1 where not 
    (nickname = '$nick' and password = '$md5pass') 
and not exists 
    (select 1 from nicknames where nickname = '$nick') 

Answer 1

這個怎麼樣？

select coalesce(max(nickname), '$nick') 
from nicknames 
where nickname = '$nick' and password = '$md5pass';