SQL condition on firstname and lastname without append or concat -

you have 2 tables customers , blacklist, both columns firstname , lastname.

how find customers? please note cannot append or concatenate lastname firstname(or vice versa) because of character limit.

i think left join work. please confirm.

select c.lastname,c.firstname curtomers c left join blacklist b on (c.lastname = b.lastname , c.firstname = b.lastname) b.firstname null , b.lastname null 

select    c.*      customer c not exists (   select  *      blacklist b     c.firstname = b.firstname     ,   c.lastname = b.lastname ) 

i assume you're inferring "good customer" 1 not in blacklist table? also, have no idea dbms you're using.