Oracle SQL-ALTER VIEW：ORA-00922：丢失或无效的选项

Question

I want to add a primary key constraint to my column, but Oracle gives me the following error message:

ORA-00922: missing or invalid option

SQL:

ALTER VIEW view_my_departments
add CONSTRAINT department_id_pk
    PRIMARY KEY (department_id);

Answer 1

Views do not have constraints. A view is simply a query that is saved with a name. Because it's a query, it returns a result set and is thus interchangeable with a table in terms of queries.

However, there is no actual data persisted in it. Only tables have data and thus tables may have constraints. Find out which table contains department_id (probably called department I'm guessing?) and add the constraint to that using.

ALTER TABLE department
add CONSTRAINT department_id_pk
    PRIMARY KEY (department_id);

Querying a table is like using a sub-query.

If "myview" is defined as:

select r.a, ro.b, u.c
from registration r
inner join roster ro on r.roster_id = ro.roster_id
inner join user u on u.user_id = ro.user_id

Then the database will interpret the following query

select a, b, c
from myview
where x = 1

as

select a, b, c
from (select r.a, ro.b, u.c
      from registration r
      inner join roster ro on r.roster_id = ro.roster_id
      inner join user u on u.user_id = ro.user_id)
where x = 1

Answer 2

Here, they must be written with disable clause as it cannot be validated.

So try,

ALTER VIEW view_my_departments
add CONSTRAINT department_id_pk
    PRIMARY KEY (department_id) disable;