Database User Authorization¶

Database User¶

To create the user name, see Identifier.

CUBRID has two types of users by default: DBA and PUBLIC. At initial installation of the product, no password is set.

• All users have authorization granted to the PUBLIC user. All users of the database are automatically the members of PUBLIC. Granting authorization to the PUBLIC means granting it all users.
• The DBA user has the authorization of the database administrator. The DBA automatically becomes the member of all users and groups. That is, the DBA is granted the access for all tables. Therefore, there is no need to grant authorization explicitly to the DBA and DBA members. Each database user has a unique name. The database administrator can create multiple users simultaneously using the cubrid createdb utility (see cubrid Management Utilities for details). A database user cannot have a member who already has the same authorization. If authorization is granted to a user, all members of the user is automatically granted the same authorization.

Managing User¶

DBA and DBA members can create, drop and alter users by using SQL statements. At the initial installation, passwords for users are not configured.

CREATE USER user_name
[ PASSWORD password ]
[ GROUPS user_name [ {, user_name } ... ] ]
[ MEMBERS user_name [ {, user_name } ... ] ] ;

DROP USER user_name;

ALTER USER user_name PASSWORD password;

• user_name: Specifies the user name to create, delete or change.
• password: Specifies the user password to create or change.

The following example shows how to create a user (Fred), change a password, and delete the user.

CREATE USER Fred;
ALTER USER Fred PASSWORD '1234';
DROP USER Fred;

The following example shows how to create a user and add member to the user. By the following statement, company becomes a group that has engineering, marketing and design as its members. marketing becomes a group with members smith and jones, design becomes a group with a member smith, and engineering becomes a group with a member brown.

CREATE USER company;
CREATE USER engineering GROUPS company;
CREATE USER marketing GROUPS company;
CREATE USER design GROUPS company;
CREATE USER smith GROUPS design, marketing;
CREATE USER jones GROUPS marketing;
CREATE USER brown GROUPS engineering;

The following example shows how to create the same groups as above but use the MEMBERS keyword instead of GROUPS.

CREATE USER smith;
CREATE USER brown;
CREATE USER jones;
CREATE USER engineering MEMBERS brown;
CREATE USER marketing MEMBERS smith, jones;
CREATE USER design MEMBERS smith;
CREATE USER company MEMBERS engineering, marketing, design;

Granting Authorization¶

In CUBRID, the smallest grant unit of authorization is a table. You must grant appropriate authorization to other users (groups) before allowing them to access the table you created.

You don't need to grant authorization individually because the members of the granted group have the same authorization. The access to the (virtual) table created by a PUBLIC user is allowed to all users. You can grant access authorization to a user by using the GRANT statement.

GRANT operation [ { ,operation } ... ] ON table_name [ { ,table_name } ... ]
TO user [ { ,user } ... ] [ WITH GRANT OPTION ] ;

• operation: Specifies an operation that can be used when granting authorization. The following table shows operations.

  • SELECT: Allows to read the table definitions and retrieve records. The most general type of permissions.
  • INSERT: Allows to create records in the table.
  • UPDATE: Allows to modify the records already existing in the table.
  • DELETE: Allows to delete records in the table.
  • ALTER: Allows to modify the table definition, rename or delete the table.
  • INDEX: Allows to call table methods or instance methods.
  • EXECUTE: Allows to call table methods or instance methods.
  • ALL PRIVILEGES: Includes all permissions described above.

• table_name: Specifies the name of a table or virtual table to be granted.

• user: Specifies the name of a user (group) to be granted. Enter the login name of the database user or PUBLIC, a system-defined user. If PUBLIC is specified, all database users are granted with the permission.

• WITH GRANT OPTION: WITH GRANT OPTION allows the grantee of authorization to grant that same authorization to another user.

The following example shows how to grant the SELECT authorization for the olympic table to smith (including his members).

GRANT SELECT ON olympic TO smith;

The following example shows how to grant the SELECT, INSERT, UPDATE and DELETE authorization on the nation and athlete tables to brown and jones (including their members).

GRANT SELECT, INSERT, UPDATE, DELETE ON nation, athlete TO  brown, jones;

The following example shows how to grant every authorization on the tbl1 and tbl2 tables to all users(public).

CREATE TABLE tbl1 (a INT);
CREATE TABLE tbl2 (a INT);
GRANT ALL PRIVILEGES ON tbl1, tbl2 TO public;

The following example shows how to grant retrieving authorization on the record and history tables to brown. Using WITH GRANT OPTION allows brown to grant retrieving to another users. brown can grant authorization to others within his authorization.

GRANT SELECT ON record, history TO brown WITH GRANT OPTION;

Revoking Authorization¶

You can revoke authorization using the REVOKE statement. The authorization granted to a user can be revoked anytime. If more than one authorization is granted to a user, all or part of the authorization can be revoked. In addition, if authorization on multiple tables is granted to more than one user using one GRANT statement, the authorization can be selectively revoked for specific users and tables.

If the authorization (WITH GRANT OPTION) is revoked from the grantor, the authorization granted to the grantee by that grantor is also revoked.

REVOKE operation [ { , operation } ... ] ON table_name [ { , class_name } ... ]
FROM user [ { , user } ... ] ;

• operation: Indicates an operation that can be used when granting authorization (see Syntax in Granting Authorization for details).
• table_name: Specifies the name of the table or virtual table to be granted.
• user: Specifies the name of the user (group) to be granted.

The following example shows how to grant SELECT, INSERT, UPDATE and DELETE authorization to smith and jones so that they can perform on the nation and athlete tables.

GRANT SELECT, INSERT, UPDATE, DELETE ON nation, athlete TO smith, jones;

The following example shows how to execute the REVOKE statement; this allows jones to have only SELECT authorization. If jones has granted authorization to another user, the user is also allowed to execute SELECT only.

REVOKE INSERT, UPDATE, DELETE ON nation, athlete FROM jones;

The following example shows how to execute the REVOKE statement revoking all authorization that has granted to smith. smith is not allowed to execute any operations on the nation and athlete tables once this statement is executed.

REVOKE ALL PRIVILEGES ON nation, athlete FROM smith;

Changing Owner¶

Database Administrator (DBA) or a member of the DBA group can change the owner of table, view, trigger, and Java stored functions/procedures by using the following query.

ALTER [TABLE | CLASS | VIEW | VCLASS | TRIGGER | PROCEDURE | FUNCTION] name OWNER TO user_id;

• name: The name of schema object of which owner is to be changed
• user_id: User ID

ALTER TABLE test_tbl OWNER TO public;
ALTER VIEW test_view OWNER TO public;
ALTER TRIGGER test_trigger OWNER TO public;
ALTER FUNCTION test_function OWNER TO public;
ALTER PROCEDURE test_procedure OWNER TO public;

User Authorization Management METHOD¶

The database administrator (DBA) can check and modify user authorization by calling authorization-related methods defined in db_user where information about database user is stored, or db_authorizations (the system authorization class). The administrator can specify db_user or db_authorizations depending on the method to be called, and store the return value of a method to a variable. In addition, some methods can be called only by DBA or members of DBA group.

CALL method_definition ON CLASS auth_class [ TO variable ] [ ; ]
CALL method_definition ON variable [ ; ]

login( ) method

As a class method of db_user class, this method is used to change the users who are currently connected to the database. The name and password of a new user to connect are given as arguments, and they must be string type. If there is no password, a blank character ('') can be used as the argument. DBA and DBA members can call the login( ) method without a password.

-- Connect as DBA user who has no password
CALL login ('dba', '') ON CLASS db_user;

-- Connect as a user_1 whose password is cubrid
CALL login ('user_1', 'cubrid') ON CLASS db_user;

add_user( ) method

As a class method of db_user class, this method is used to add a new user. The name and password of a new user to add are given as arguments, and they must be string type. At this time, the new user name should not duplicate any user name already registered in a database. The add_user( ) can be called only by DBA or members of DBA group.

-- Add user_2 who has no password
CALL add_user ('user_3', '') ON CLASS db_user;

-- Add user_3 who has no password, and store the return value of a method into an admin variable
CALL add_user ('user_2', '') ON CLASS db_user to admin;

drop_user( ) method

As a class method of db_user class, this method is used to drop an existing user. Only the user name to be dropped is given as an argument, and it must be a string type. However, the owner of a class cannot be dropped thus DBA needs to specify a new owner of the class before dropping the user. The drop_user( ) method can be also called only by DBA or members of DBA.

-- Delete user_2
CALL drop_user ('user_2') ON CLASS db_user;

find_user( ) method

As a class method of db_user class, this method is used to find a user who is given as an argument. The name of a user to be found is given as an argument, and the return value of the method is stored into a variable that follows 'to'. The stored value can be used in a next query execution.

-- Find user_2 and store it into a variable called 'admin'
CALL find_user ('user_2') ON CLASS db_user to admin;

set_password( ) method

This method is an instance method that can call each user instance, and it is used to change a user's password. The new password of a specified user is given as an argument. General users other than DBA and DBA group members can only change their own passwords.

-- Add user_4 and store it into a variable called user_common
CALL add_user ('user_4','') ON CLASS db_user to user_common;

-- Change the password of user_4 to 'abcdef'
CALL set_password('abcdef') on user_common;

change_owner() method

As a class method of db_authorizations class, this method is used to change the owner of a class. The name of a class for which you want to change the owner, and the name of a new owner are given as arguments. At this time, the class and owner that are specified as an argument must exist in a database. Otherwise, an error occurs. change_owner( ) can be called only by DBA or members of DBA group. The ALTER ... OWNER query has the same role as the method. See Changing Owner.

-- Change the owner of table_1 to user_4
CALL change_owner ('table_1', 'user_4') ON CLASS db_authorizations;

The following example shows a CALL statement that calls the find_user method defined in the system table db_user. It is called to determine whether the database user entered as the find_user exists. The first statement calls the table method defined in the db_user class. The name (db_user in this case) is stored in x if the user is registered in the database. Otherwise, NULL is stored.

The second statement outputs the value stored in the variable x. In this query statement, the DB_ROOT is a system class that can have only one record. It can be used to output the value of sys_date or other registered variables. For this purpose, the DB_ROOT can be replaced by another table having only one record.

CALL find_user('dba') ON CLASS db_user to x;

Result
======================
db_user

SELECT x FROM db_root;

x
======================
db_user

With find_user, you can determine if the user exists in the database depending on whether the return value is NULL or not.