寻找用户推荐人。写一个查询语句,返回一个客户列表,列表中客户的推荐人的编号都 不是 2。
对于示例数据,结果为:
±-----+
| name |
±-----+
| Will |
| Jane |
| Bill |
| Zack |
±-----+
DROP TABLE IF EXISTS `customer`;
CREATE TABLE `customer` (
`id` int(11) NOT NULL,
`name` varchar(255) NOT NULL,
`referee_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `customer` VALUES ('1', 'Will', null);
INSERT INTO `customer` VALUES ('2', 'Jane', null);
INSERT INTO `customer` VALUES ('3', 'Alex', '2');
INSERT INTO `customer` VALUES ('4', 'Bill', null);
INSERT INTO `customer` VALUES ('5', 'Zack', '1');
INSERT INTO `customer` VALUES ('6', 'Mark', '2');
sql语句如下:
SELECT name FROM customer WHERE referee_id != 2 OR referee_id IS NULL;