更改表将列添加为select语句

Question

如何做这样的事......

alter table customer_schedule add (week_number as (TO_CHAR((SCHEDULE_DATE),'iw')) 

其中SCHEDULE_DATE是表中现有的列之一

Answer 1

这是您需要VIRTUAL COLUMN的地方.如果你在11g及以上,你当然可以 -

alter table table_name
add (column_name [data_type] [generated always] as (column_expression) [virtual]);

在你的情况下,它会像 -

alter table customer_schedule add (week_number data_type generated always as (TO_CHAR((SCHEDULE_DATE),'iw') VIRTUAL)