gaoshanwudi的专栏

Oracle上没有自增字段，可以使用索引和触发器来达到此目的 第一步：创建SEQUENCE create sequence s_country_id increment by 1 start with 1 maxvalue 999999999; 第二步：创建一个基于该表的before insert 触发器，在触发器中使用该SEQUENCE create or replace trigger bef

In MySQL it is pretty easy to drop a table if it exists already. In Oracle and Microsoft’s SQL Server it is a little more complicated. Today I want to present you the solutions for these two DBMS’.

SQL中的单记录函数 1.ASCII 返回与指定的字符对应的十进制数; SQL> select ascii('A') A,ascii('a') a,ascii('0') zero,ascii(' ') space from dual;         A         A      ZERO     SPACE --------- --------- --------- -----