为什么要用触发器?DROP TABLE
Name
DROP TABLE -- remove a table
Synopsis
DROP TABLE name [, ...] [ CASCADE | RESTRICT ]
Description
DROP TABLE removes tables from the database. Only its owner may destroy a table. To empty a table of rows, without destroying the table, use DELETE. DROP TABLE always removes any indexes, rules, triggers, and constraints that exist for the target table. However, to drop a table that is referenced by a foreign-key constraint of another table, CASCADE must be specified. (CASCADE will remove the foreign-key constraint, not the other table entirely.)
Name
DROP TABLE -- remove a table
Synopsis
DROP TABLE name [, ...] [ CASCADE | RESTRICT ]
Description
DROP TABLE removes tables from the database. Only its owner may destroy a table. To empty a table of rows, without destroying the table, use DELETE. DROP TABLE always removes any indexes, rules, triggers, and constraints that exist for the target table. However, to drop a table that is referenced by a foreign-key constraint of another table, CASCADE must be specified. (CASCADE will remove the foreign-key constraint, not the other table entirely.)
这个函数是执行你的动作(对另一个表B的操作)的函数,返回值是 trigger
2.实现触发器,这个动作是去调用 开始建立的触发器函数 , 要说明是在对A表操作之前还是之后 去调用那个函数CREATE FUNCTION a_trigger_fun() RETURNS trigger AS '
begin
insert into b values(new.f1,new.f2,new.f3,new.f4,new.f5);
return new;
end;' LANGUAGE 'plpgsql' VOLATILE;
CREATE TRIGGER a_intrigger AFTER INSERT ON a FOR EACH ROW EXECUTE PROCEDURE a_trigger_fun();