oracl 和db2 常用语法比较: 1、取前N条记录 Oracle:Select * from TableName where rownum <= N; DB2:Select * from TableName fetch first N rows only; 2、取得系统日期 Oracle:Select sysdate from dual; DB2:Select current timestamp from sysibm.sysdummy1; 3、空值转换 Oracle:Select
代码如下:on delete cascade
当你更新或删除主键表时,那么外键表也会跟随一起更新或删除,需要在建表时设置级联属性
CREATE TABLE Countries(CountryId INT PRIMARY KEY) INSERT INTO Countries (CountryId) VALUES (1) INSERT INTO Countries (CountryId) VALUES (2) INSERT INTO Countries (CountryId) VALUES (3)