6.4: MySQL
MySQL 1 (TRUE), (FALSE) NULL (, , FALSE):
NOT !
NOT (). 1, 0, 0. : NOT NULL NULL:
mysql> select NOT 1;
-> 0
mysql> select NOT NULL;
-> NULL
mysql> select ! (1+1);
-> 0
mysql> select !, 1+1;
-> 1
1 , , (!1)+1.
OR ||
OR (). 1, 0 NULL:
mysql> select 1 || 0;
-> 1
mysql> select 0 || 0;
-> 0
mysql> select 1 || NULL;
-> 1
AND &&
AND (). 0, 0 NULL, 1:
mysql> select 1 && NULL;
-> 0
mysql> select 1 && 0;
-> 0