Problem with creating "updatable" view. Any ideas?

Question

Hello to nice people!
I'm trying to create plain, simple updatable view such as:
CREATE OR REPLACE VIEW v_admin_maint
(from_addrs,mail_invoice_addrs,auth_off,location_cd) AS SELECT
A.from_addrs, A.mail_invoice_addrs, A.auth_off,
A.location_cd FROM admin_maint A, sysusers B WHERE A.location_cd
= B.location_cd and B.user_id = USER;
TABLE admin_maint
from_addrs,
mail_invoice_addrs,
auth_off,
location_cd (PRIMARY KEY)
TABLE sysusers
USER_ID (PRIMARY KEY)
FIRST_NAME
LAST_NAME
LOCATION_CD
View works great as view-only, but I got an error on update
statement "ORA-01779: cannot modify a column which maps to a non
key-preserved table".
UPDATE v_admin_maint SET from_addrs = 'test' where location_cd
= 'HOME';
TABLE admin_maint does have PK and this column included into
VIEW.
Any ideas? Please advice.

Answer 1

You need to create a unique index on the location_cd column of
the sysusers table, then re-create your view:
SQL> ALTER TABLE sysusers
  2  ADD CONSTRAINT sysusers_location_cd_uk
  3  UNIQUE (location_cd)
  4  /
Table altered.
SQL> CREATE OR REPLACE VIEW v_admin_maint
  2    (from_addrs,
  3     mail_invoice_addrs,
  4     auth_off,
  5     location_cd)
  6  AS
  7  SELECT A.from_addrs,
  8         A.mail_invoice_addrs,
  9         A.auth_off,
10         A.location_cd
11  FROM   admin_maint A,
12         sysusers B
13  WHERE  A.location_cd = B.location_cd
14  and    B.user_id = USER
15  /
View created.
SQL> SELECT      column_name,
  2              updatable
  3  FROM        user_updatable_columns
  4  WHERE       table_name = 'V_ADMIN_MAINT'
  5  /
COLUMN_NAME                    UPD
FROM_ADDRS                     YES
MAIL_INVOICE_ADDRS             YES
AUTH_OFF                       YES
LOCATION_CD                    YES
SQL> UPDATE v_admin_maint
  2  SET    from_addrs = 'test'
  3  where  location_cd = 'HOME'
  4  /
1 row updated.