Question

我想在表格的电子邮件ID列中存储多个电子邮件ID，作为多值属性。我怎样才能在oracle中做到这一点？

Answer 1

执行此操作的传统关系方式是使用子堆表：

create table emails 
    (id number
     , email_address varchar2(254)
     , constraint em_t23_fk foreign key (id)
                  references t23 (id)
                  )
/

但是，你暗示了一个嵌套表：

create type email_t as object
    (email_address varchar2(254))
/

create type email_nt as table of email_t
/
alter table t23
    add emails email_nt
    nested table emails store as emails_table
/

以下是它的工作原理：

SQL> update t23
  2  set emails = email_nt (email_t('sam_i_am@example.com')
  3                          , email_t('green_eggs_n_ham@yahoo.co.uk'))
  4  where id = 222
  5  /

1 row updated.

SQL> select * from t23
  2  where id = 222
  3  /

        ID NAME                           DOB
---------- ------------------------------ ---------
EMAILS(EMAIL_ADDRESS)
----------------------------------------------------------------------------------
       222 Sam-I-Am                       06-AUG-02
EMAIL_NT(EMAIL_T('sam_i_am@example.com'), EMAIL_T('green_eggs_n_ham@yahoo.co.uk'))


SQL>

修改

VARRAY的解决方案基本相同：

SQL> alter table t23 2 drop column emails 3 / Table altered. SQL> create type email_va as varray(5) of varchar2(254) 2 / Type created. SQL> alter table t23 2 add emails email_va 3 / Table altered. SQL> update t23 2 set emails = email_va ('sam_i_am@example.com' 3 , 'green_eggs_n_ham@yahoo.co.uk') 4 where id = 222 5 / 1 row updated. SQL> select t23.name 2 , e.* 3 from t23 4 , table (t23.emails) e 5 where t23.id = 222 6 / NAME COLUMN_VALUE ------------------------------ --------------------------------- Sam-I-Am sam_i_am@example.com Sam-I-Am green_eggs_n_ham@yahoo.co.uk SQL>

Answer 2

执行此操作的标准方法是定义第二个表，您可以在其中存储每行一封电子邮件。

Oracle还支持nested tables，因此单个属性列可以包含多个值。

如何在oracle中实现多值属性？

2 个答案: