select dbtable from profiles where ( email = 'blah@test.com' ) into @tableName;
set @queryy = CONCAT(CONCAT('INSERT INTO ', @tableName), ' values ( null, null, \'blah@test.com\', \'testing\' )');
prepare myQuery from @queryy;
execute myQuery;
deallocate prepare myQuery;
I think it should help you solve your problem.