The given database contains a masterdata (MD) Schema and an application specific Schema (APP). In the APP Schema we have a view which provides the applications data from one table in the scheme joined with data from the MD Schema.
Example: Think of an address book application, which holds an address table, but cities and ZIP codes are joined from a masterdata table in another Schema which is maintained centrally.
CREATE VIEW view_adress AS
SELECT app.ID, app.Street, app.ZIP, zip.CITYNAME
FROM APP.adress app
LEFT OUTER JOIN MD.zipcodes zip
ON app.ZIP = zip.ZIP
This is very simplified. The actual view I use is a lot more complicated like that and therefore I implemented an INSTEAD OF INSERT, UPDATE Trigger to map INSERTs on the view to the correct base table in my APP Schema.
The application users (role) is granted SELECT,INSERT,UPDATE,DELETE on all tables inside this APP Schema. They are also granted SELECT on that zipcode table in the master data Schema.
When I insert on that view, I get an "ORA-01720: Grant Option Does Not Exist"... I don't know the exact cause of this error, but it can be assumed that the INSTEAD-OF Trigger never INSERTS on the ZIP Code Table, only on the address table.
I understand, that granting the application users INSERT privilege on the zipcode table would probably resolve this issue, but I am feeling uncomfortable granting INSERTs on tables to users which they never should edit in any way, because these are only lookups.
Is there another, possibly "the correct way" to solve this?
By "insufficient permissions error" do you mean this?
ORA-01720: grant option does not exist for 'MD.ZIPCODES'
*Cause: A grant was being performed on a view or a view was being replaced
and the grant option was not present for an underlying object.
*Action: Obtain the grant option on all underlying objects of the view or
revoke existing grants on the view.
If so, the solution is that you need to grant the relevant permissions to the schema owning the view - not to the roles that use the view:
grant insert on md.zipcodes to app with grant option;
It's true that you are still having to grant a permission that is logically not required, but you are not granting it to users, only the app schema.
I have created a Sequence for the table and on creation of a trigger I got the following error:
ORA-04089: cannot create triggers on objects owned by SYS.
Can someone explain me what is it and how can it be solved? Since I'm a beginner, is there a simple way to solve it?
MY TABLE NAME IS-testing.
create sequence example_seq
start with 1
increment by 1
nomaxvalue;
create trigger example_trigger
before insert on testing
for each row
begin
select example_seq.nextval into :new.id from dual;
end;
The error message is quite clear:
ORA-04089: cannot create triggers on objects owned by SYS.
So obviously you are logged in as SYS, and creating objects in that user;s schemas. You must not do this. SYS is the user who owns the data dictionary and all the objects which manage the database. Changing the SYS schema is, at best, bad practice and runs the risk of corrupting the database. Find out more.
What you need to do is create a new user, for your application objects. This is quite simple. Connect as SYSTEM (avoid using SYS for menial tasks):
create user your_name_here identified by << password >>
/
grant create session, create table, create sequence, create trigger
to your_name_here
/
Obviously you will need to grant more privileges. The full list is in the documentation.
Once you've created your new user you can connect to it and create all the objects you desire.
I have a situation in our Oracle environment where I would like to be able to grant select permissions to a certain user/group on all views in a particular schema.
I realize that I could write a dynamic statement to iterate over all the views in the schema and grant permissions to them individually as shown here but I would like to be able to have this apply to all views that exist in the schema now or in the future.
I was also contemplating the possibility of writing a DDL trigger that could monitor for the creation of new views but setting permissions in a trigger isn't something I've seen done before and doesn't seem like accepted practice.
Basically, is there a VIEW analog to the GRANT EXECUTE ANY PROCEDURE?
The EXECUTE ANY PROCEDURE grant allows a user to execute any procedure in any schema in the database, not just those in a particular schema. You can grant a user the SELECT ANY TABLE privilege-- that will allow the user to query any table or view in any schema in the database not just those in a particular schema. That's the analogous privilege, it just seems unlikely that either is really what you're after.
Since views should not be created dynamically, this sort of requirement would normally be handled by simply including the appropriate GRANT statements in the scripts that create the new views which get promoted up through the environments. Dynamically granting privileges is generally frowned upon because it generally implies that you have issues with your change control process that need to be addressed.
I have, for third party applications that insist on creating new objects periodically, created a DDL trigger that grants privileges on new objects. In order to do that, you would need to submit a job that actually does the GRANT. A GRANT is a DDL statement so it issues an implicit commit and implicit commits aren't allowed in triggers, you have to have a separate job that runs moments after the object is created. This means that you end up with a number of moving pieces that generally makes your environment more complex.
I have created a read only user A in Oracle DB. (who can access schema X but cannot alter anything) Then i am asked to give user A create table privilege on schema X.
However as far as i know, i can either give create any table privilege to user A or create table privilege. One of them is for creating table on his/her own schema, other one is for creating table on all schemas, which should not be preferred.
So i have given create any table privilege to user A and then created a trigger which prevents user A from creating a table on schemas other than X.
HOWEVER,
I needed to create the trigger as user A, and now user A can easily drop that trigger because A is the owner.
Is there any way i can prevent user A from dropping triggers even if he/she's the owner ?
As far as i experienced,user A does not need to have drop any trigger or administer database trigger privileges since trigger is already his/her own.
Is there any workaround for this ? Or should i search for an alternative way to give create table permission on other schemas.
Thank you in advance.
No, there is no way to prevent a user from dropping an object that it owns.
There's also no way to directly allow for user A to create objects in user X's schema, unless you start granting "ANY" privileges.
One possible workaround may be to create a stored procedure in user X's schema that will create objects in user X's schema (execute immediate) and grant EXECUTE privilege on said stored procedure to user A.
So, in this way, user A could do something like:
exec create_in_x_schema('create table blah(a number)');
And that procedure would just do an execute immediate on the string passed in.
A procedure that looks something like:
create or replace procedure create_in_x_schema(doit varchar2)
begin
execute immediate doit;
end;
/
ought to do it.
(Code is untested, but should give you some idea.)
Hope that helps.
What is the difference between a user and a schema in Oracle?
From Ask Tom
You should consider a schema to be the user account and collection of all objects therein
as a schema for all intents and purposes.
SCOTT is a schema that includes the EMP, DEPT and BONUS tables with various grants, and
other stuff.
SYS is a schema that includes tons of tables, views, grants, etc etc etc.
SYSTEM is a schema.....
Technically -- A schema is the set of metadata (data dictionary) used by the database,
typically generated using DDL. A schema defines attributes of the database, such as
tables, columns, and properties. A database schema is a description of the data in a
database.
I believe the problem is that Oracle uses the term schema slightly differently from what it generally means.
Oracle's schema (as explained in Nebakanezer's answer): basically the set of all tables and other objects owned by a user account, so roughly equivalent to a user account
Schema in general: The set of all tables, sprocs etc. that make up the database for a given system / application (as in "Developers should discuss with the DBAs about the schema for our new application.")
Schema in sense 2. is similar, but not the same as schema in sense 1. E.g. for an application that uses several DB accounts, a schema in sense 2 might consist of several Oracle schemas :-).
Plus schema can also mean a bunch of other, fairly unrelated things in other contexts (e.g. in mathematics).
Oracle should just have used a term like "userarea" or "accountobjects", instead of overloadin "schema"...
From WikiAnswers:
A schema is collection of database objects, including logical structures such as tables, views, sequences, stored procedures, synonyms, indexes, clusters, and database links.
A user owns a schema.
A user and a schema have the same name.
The CREATE USER command creates a user. It also automatically creates a schema for that user.
The CREATE SCHEMA command does not create a "schema" as it implies, it just allows you to create multiple tables and views and perform multiple grants in your own schema in a single transaction.
For all intents and purposes you can consider a user to be a schema and a schema to be a user.
Furthermore, a user can access objects in schemas other than their own, if they have permission to do so.
Think of a user as you normally do (username/password with access to log in and access some objects in the system) and a schema as the database version of a user's home directory. User "foo" generally creates things under schema "foo" for example, if user "foo" creates or refers to table "bar" then Oracle will assume that the user means "foo.bar".
This answer does not define the difference between an owner and schema but I think it adds to the discussion.
In my little world of thinking:
I have struggled with the idea that I create N number of users where I want each of these users to "consume" (aka, use) a single schema.
Tim at oracle-base.com shows how to do this (have N number of users and each of these users will be "redirected" to a single schema.
He has a second "synonym" approach (not listed here). I am only quoting the CURRENT_SCHEMA version (one of his approaches) here:
CURRENT_SCHEMA Approach
This method uses the CURRENT_SCHEMA session attribute to automatically
point application users to the correct schema.
First, we create the schema owner and an application user.
CONN sys/password AS SYSDBA
-- Remove existing users and roles with the same names.
DROP USER schema_owner CASCADE;
DROP USER app_user CASCADE;
DROP ROLE schema_rw_role;
DROP ROLE schema_ro_role;
-- Schema owner.
CREATE USER schema_owner IDENTIFIED BY password
DEFAULT TABLESPACE users
TEMPORARY TABLESPACE temp
QUOTA UNLIMITED ON users;
GRANT CONNECT, CREATE TABLE TO schema_owner;
-- Application user.
CREATE USER app_user IDENTIFIED BY password
DEFAULT TABLESPACE users
TEMPORARY TABLESPACE temp;
GRANT CONNECT TO app_user;
Notice that the application user can connect, but does not have any
tablespace quotas or privileges to create objects.
Next, we create some roles to allow read-write and read-only access.
CREATE ROLE schema_rw_role;
CREATE ROLE schema_ro_role;
We want to give our application user read-write access to the schema
objects, so we grant the relevant role.
GRANT schema_rw_role TO app_user;
We need to make sure the application user has its default schema
pointing to the schema owner, so we create an AFTER LOGON trigger to
do this for us.
CREATE OR REPLACE TRIGGER app_user.after_logon_trg
AFTER LOGON ON app_user.SCHEMA
BEGIN
DBMS_APPLICATION_INFO.set_module(USER, 'Initialized');
EXECUTE IMMEDIATE 'ALTER SESSION SET current_schema=SCHEMA_OWNER';
END;
/
Now we are ready to create an object in the schema owner.
CONN schema_owner/password
CREATE TABLE test_tab (
id NUMBER,
description VARCHAR2(50),
CONSTRAINT test_tab_pk PRIMARY KEY (id)
);
GRANT SELECT ON test_tab TO schema_ro_role;
GRANT SELECT, INSERT, UPDATE, DELETE ON test_tab TO schema_rw_role;
Notice how the privileges are granted to the relevant roles. Without
this, the objects would not be visible to the application user. We now
have a functioning schema owner and application user.
SQL> CONN app_user/password
Connected.
SQL> DESC test_tab
Name Null? Type
----------------------------------------------------- -------- ------------------------------------
ID NOT NULL NUMBER
DESCRIPTION VARCHAR2(50)
SQL>
This method is ideal where the application user is simply an
alternative entry point to the main schema, requiring no objects of
its own.
It's very simple.
If USER has OBJECTS
then call it SCHEMA
else
call it USER
end if;
A user may be given access to schema objects owned by different Users.
Schema is an encapsulation of DB.objects about an idea/domain of intrest, and owned by ONE user. It then will be shared by other users/applications with suppressed roles. So users need not own a schema, but a schema needs to have an owner.
--USER and SCHEMA
The both words user and schema are interchangeble,thats why most people get confusion on this words below i explained the difference between them
--User User is a account to connect database(Server). we can create user by using CREATE USER user_name IDENTIFIED BY password .
--Schema
Actually Oracle Database contain logical and physical strucutre to process the data.The Schema Also Logical Structure to process the data in Database(Memory Component). Its Created automatically by oracle when user created.It Contains All Objects created by the user associated to that schema.For Example if i created a user with name santhosh then oracle createts a schema called santhosh,oracle stores all objects created by user santhosh in santhosh schema.
We can create schema by CREATE SCHEMA statement ,but Oracle Automatically create a user for that schema.
We can Drop the schema by using DROP SCHEMA schama_name RESTRICT statement but it can not delete scehema contains objects,so to drop schema it must be empty.here the restrict word forcely specify that schema with out objects.
If we try to drop a user contain objects in his schema we must specify CASCADE word because oracle does not allow you to delete user contain objects.
DROP USER user_name CASCADE
so oracle deletes the objects in schema and then it drops the user automatically,Objects refered to this schema objects from other schema like views and private synonyms goes to invalid state.
I hope now you got the difference between them,if you have any doubts on this topic,please feel free to ask.
Thank you.
A user account is like relatives who holds a key to your home, but does not own anything i.e. a user account does not own any database object...no data dictionary...
Whereas a schema is an encapsulation of database objects. It's like the owner of the house who owns everything in your house and a user account will be able to access the goods at the home only when the owner i.e. schema gives needed grants to it.
A schema and database users are same but if schema has owned database objects and they can do anything their object but user just access the objects, They can't DO any DDL operations until schema user give you the proper privileges.
Based on my little knowledge of Oracle... a USER and a SCHEMA are somewhat similar. But there is also a major difference. A USER can be called a SCHEMA if the "USER" owns any object, otherwise ... it will only remain a "USER". Once the USER owns at least one object then by virtue of all of your definitions above.... the USER can now be called a SCHEMA.
User: Access to resource of the database. Like a key to enter a house.
Schema: Collection of information about database objects. Like Index in your book which contains the short information about the chapter.
Look here for details
For most of the people who are more familiar with MariaDB or MySQL this seems little confusing because in MariaDB or MySQL they have different schemas (which includes different tables, view , PLSQL blocks and DB objects etc) and USERS are the accounts which can access those schema. Therefore no specific user can belong to any particular schema. The permission has be to given to that Schema then the user can access it. The Users and Schema is separated in databases like MySQL and MariaDB.
In Oracle schema and users are almost treated as same. To work with that schema you need to have the permission which is where you will feel that the schema name is nothing but user name. Permissions can be given across schemas to access different database objects from different schema. In oracle we can say that a user owns a schema because when you create a user you create DB objects for it and vice a versa.
Schema is a container of objects.
It is owned by a user.
Well, I read somewhere that if your database user has the DDL privileges then it's a schema, else it's a user.