zlnyjj的专栏

CREATE SEQUENCE AutoInc INCREMENT BY 1 START WITH 1 MAXVALUE 99999 CYCLE NOCACHE;建一个BeforeInsert触发器：SELECT AutoInc.nextval from dual;

1.求字持串的长度LENGTH您可用LENGTH函数求字符串的长度。LENGTH返回一个数值。该值等于参数中的字符个数。例：使用LENGTH函数    SQL＞select Last_Name, length(Last_Name) from customer order by LastName;2.使用SUBSTR函数从字符串中提取子串语法：    SUBSTR函数的语法如下：    SUBSTR