如果 INTERVAL() 函数的第一个参数为 NULL，MySQL 将返回什么？
如果 INTERVAL() 函数的第一个参数为 NULL，MySQL 将返回 -1 作为输出。下面的例子将演示它 -
mysql> Select INTERVAL(NULL,20,32,38,40,50,55); +--------------------------------------+ | INTERVAL(NULL,20,32,38,40,50,55) | +--------------------------------------+ | -1 | +--------------------------------------+ 1 row in set (0.00 sec)登录后复制
mysql> Select INTERVAL(NULL,20,32,NULL,40,50,NULL); +--------------------------------------+ | INTERVAL(NULL,20,32,NULL,40,50,NULL) | +--------------------------------------+ | -1 | +--------------------------------------+ 1 row in set (0.00 sec)登录后复制
mysql> Select INTERVAL(50,20,NULL,55,40,50,NULL); +------------------------------------+ | INTERVAL(50,20,NULL,55,40,50,NULL) | +------------------------------------+ | 2 | +------------------------------------+ 1 row in set (0.00 sec)登录后复制
