【转】Oracle virtual column（虚拟列）

1 HR@bear> create table inv(
2 inv_id number,
3 inv_count number,
4 inv_status generated always as
5 case when inv_count <= 100 then 'GETTING LOW'
6 when inv_count > 100 then 'OKAY'
7 end)
8 );

alter table inv add inv_comm generated always as(inv_count * 0.1) virtual;

alter table inv modify inv_status generated always as(
case when inv_count <= 50 then 'NEED MORE'
when inv_count >50 and inv_count <=200 then 'GETTING LOW'
when inv_count > 200 then 'OKAY'
end);

SQL> update inv set inv_count=100 where inv_status='OKAY';