Mysql逻辑运算符实战

淩亂°似流年 2021-07-24 14:21 485阅读 0赞

**一 分别使用非运算符"NOT"和"！"进行逻辑判断**

mysql> SELECT NOT 10, NOT (1-1), NOT -5, NOT NULL, NOT 1 + 1;
    +--------+-----------+--------+----------+-----------+
    | NOT 10 | NOT (1-1) | NOT -5 | NOT NULL | NOT 1 + 1 |
    +--------+-----------+--------+----------+-----------+
    |      0 |         1 |      0 |     NULL |         0 |
    +--------+-----------+--------+----------+-----------+
    1 row in set (0.00 sec)
    
    
    mysql> SELECT !10, !(1-1), !-5, ! NULL, ! 1 + 1;
    +-----+--------+-----+--------+---------+
    | !10 | !(1-1) | !-5 | ! NULL | ! 1 + 1 |
    +-----+--------+-----+--------+---------+
    |   0 |      1 |   0 |   NULL |       1 |
    +-----+--------+-----+--------+---------+
    1 row in set (0.00 sec)

**二 分别使用与运算符"AND"和"&&"进行逻辑判断**

mysql> SELECT  1 AND -1,1 AND 0,1 AND NULL, 0 AND NULL;
    +----------+---------+------------+------------+
    | 1 AND -1 | 1 AND 0 | 1 AND NULL | 0 AND NULL |
    +----------+---------+------------+------------+
    |        1 |       0 |       NULL |          0 |
    +----------+---------+------------+------------+
    1 row in set (0.00 sec)
    
    
    mysql> SELECT  1 && -1,1 && 0,1 && NULL, 0 && NULL;
    +---------+--------+-----------+-----------+
    | 1 && -1 | 1 && 0 | 1 && NULL | 0 && NULL |
    +---------+--------+-----------+-----------+
    |       1 |      0 |      NULL |         0 |
    +---------+--------+-----------+-----------+
    1 row in set (0.00 sec)

**三 分别使用或运算符"OR"和"||"进行逻辑判断**

mysql> SELECT  1 OR -1 OR 0, 1 OR 2,1 OR NULL, 0 OR NULL, NULL OR NULL;
    +--------------+--------+-----------+-----------+--------------+
    | 1 OR -1 OR 0 | 1 OR 2 | 1 OR NULL | 0 OR NULL | NULL OR NULL |
    +--------------+--------+-----------+-----------+--------------+
    |            1 |      1 |         1 |      NULL |         NULL |
    +--------------+--------+-----------+-----------+--------------+
    1 row in set (0.00 sec)
    
    
    mysql> SELECT  1 || -1 || 0, 1 || 2,1 || NULL, 0 || NULL, NULL || NULL;
    +--------------+--------+-----------+-----------+--------------+
    | 1 || -1 || 0 | 1 || 2 | 1 || NULL | 0 || NULL | NULL || NULL |
    +--------------+--------+-----------+-----------+--------------+
    |            1 |      1 |         1 |      NULL |         NULL |
    +--------------+--------+-----------+-----------+--------------+
    1 row in set (0.00 sec)

**四 使用异或运算符"XOR"进行逻辑判断**

mysql> SELECT 1 XOR 1, 0 XOR 0, 1 XOR 0, 1 XOR NULL, 1 XOR 1 XOR 1;
    +---------+---------+---------+------------+---------------+
    | 1 XOR 1 | 0 XOR 0 | 1 XOR 0 | 1 XOR NULL | 1 XOR 1 XOR 1 |
    +---------+---------+---------+------------+---------------+
    |       0 |       0 |       1 |       NULL |             1 |
    +---------+---------+---------+------------+---------------+
    1 row in set (0.00 sec)