Hi Martin,
Thank you for yor concern. I don't explore the source code of firebird, but I 
guess your opinion is  correct.
Regards,Tjioe Hian Pin
 

    On Friday, 9 December 2016, 21:13, "Köditz, Martin [email protected] 
[firebird-support]" <[email protected]> wrote:
 

     Hi,    I think the answer is simple. Since EXISTS just checks for 
existence the results are equal. So after EXISTS fetches (finds) one row the 
result is true and no further records will be checked. So there is internally 
no difference in your queries.    Please correct me if I’m wrong.    Regards, 
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