Oracle数据创建虚拟列和复合触发器的方法

create table sales  (  sales_id number,  cust_id number,  sales_amt number,  sale_category varchar2(6) /* 虚拟列名及数据类型*/  generated always as  (  case when sales_amt <= 10000 then 'LOW'  when sales_amt > 10000 and sales_amt <= 100000 then 'MEDIUM'  when sales_amt > 100000 and sales_amt <= 1000000 then 'HIGH' else 'ULTRA' end  ) virtual /*虚拟列值函数内容*/  ); 

create or replace trigger tri_sales  for update of sales_amt on SALES  compound trigger  type ty_sales_log is table of sales_log%rowtype  index by pls_integer;  coll_sales_log ty_sales_log;  ctr pls_integer:=0;  before statement is  begin  dbms_output.put_line('in before statement');  end before statement;  before each row is  begin  dbms_output.put_line('in before each row');  end before each row;  after each row is  begin  ctr := ctr+1;  dbms_output.put_line('in after each row.sales_amt'||:new.sales_amt);  coll_sales_log(ctr).sales_id := :old.sales_id;  coll_sales_log(ctr).cust_id := :old.cust_id;  coll_sales_log(ctr).sales_amt := :new.sales_amt;  end after each row;  after statement is  begin  dbms_output.put_line('in after statement');  forall counter in 1..coll_sales_log.count()  insert into sales_log(sales_id,cust_id,sales_amt)  values (coll_sales_log(counter).sales_id,coll_sales_log(counter).cust_id,coll_sales_log(counter).sales_amt);  end after statement;    /* 不能使用Insert into sales_log values  (coll_sales_log(counter));添加*/  end tri_sales;