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Managing Users Permissions on SQL Server

Posted by Praveen Kumar on February 29, 2008

Permissions are the rights to access the database objects. Permissions can be granted to a user or role to allow that user or role to perform operations such as selection, insertion or modification of data rows.

Creates an entry in the security system that allows a user in the current database to work with data in the current database or execute specific Transact-SQL statements.
Permissions Types
To perform any activity in a database, user must have the appropriate permissions. These permissions fall into three categories, which we call permissions types:

Permissions to work with data and execute procedures (object permissions).
Permissions to create a database or an item in the database (statement permissions).
Permissions to utilize permissions granted to predefined roles (implied permissions).

Syntax
Statement permissions:

GRANT { ALL | statement [ ,…n ] }
TO security_account [ ,…n ]

Object permissions:

GRANT
    { ALL [ PRIVILEGES ] | permission [ ,…n ] }
    {
        [ ( column [ ,…n ] ) ] ON { table | view }
        | ON { table | view } [ ( column [ ,…n ] ) ]
        | ON { stored_procedure | extended_procedure }
        | ON { user_defined_function }
    }
TO security_account [ ,…n ]
[ WITH GRANT OPTION ]
[ AS { group | role } ]

Examples
A. Grant statement permissions
This example grants multiple statement permissions to the users Mary and John, and the CorporateBobJ Windows NT group.

GRANT CREATE DATABASE, CREATE TABLE
TO Mary, John, [CorporateBobJ]

B. Grant object permissions within the permission hierarchy

This example shows the preferred ordering of permissions. First, SELECT permissions are granted to the public role. Then, specific permissions are granted to users Mary, John, and Tom. These users then have all permissions to the authors table.

USE pubs
GO

GRANT SELECT
ON authors
TO public
GO

GRANT INSERT, UPDATE, DELETE
ON authors
TO Mary, John, Tom
GO

C. Grant permissions to a SQL Server role

This example grants CREATE TABLE permissions to all members of the Accounting role.

GRANT CREATE TABLE TO Accounting

D. Grant permissions using the AS option

The Plan_Data table is owned by the user Jean. Jean grants SELECT permissions, specifying the WITH GRANT OPTION clause, on Plan_Data to the Accounting role. The user Jill, who is member of Accounting, wants to grant SELECT permissions on the Plan_Data table to the user Jack, who is not a member of Accounting.

Because the permission to GRANT other users SELECT permissions to the Plan_Data table were granted to the Accounting role and not Jill explicitly, Jill cannot grant permissions for the table based on the permissions granted through being a member of the Accounting role. Jill must use the AS clause to assume the grant permissions of the Accounting role.

/* User Jean */
GRANT SELECT ON Plan_Data TO Accounting WITH GRANT OPTION

/* User Jill */
GRANT SELECT ON Plan_Data TO Jack AS Accounting

SQL Server 2000 supports granting or revoking user rights to the following permissions types:

Object Permissions

The object permissions are the permissions to act on the database objects (such as tables, stored procedures and views). They consist of the following permissions:

SELECT

Enables a user to select or read data from a table or view. The SELECT permission can be applied to individual columns within a table or view, and may be applied to user-defined functions.

INSERT

Enables a user to insert new data to a table or view.

DELETE

Enables a user to delete data from a table or view.

UPDATE

Enables a user to update data in a table or view. The UPDATE permission can be applied to individual columns within a table or view, not just the entire table.

EXECUTE

Enables a user to execute a stored procedure.

DRI (declarative referential integrity)

Enables a user to add foreign key constraints on a table.

Statement Permissions

These are the permissions to create a database or an object in the database. These permissions are applied to the statement itself, rather than to a specific object defined in the database. They consist of the following permissions:

BACKUP DATABASE

The BACKUP DATABASE statement is used to back up an entire database or one or more files or filegroups.

BACKUP LOG

The BACKUP LOG statement is used to back up the transaction log.

CREATE DATABASE

The CREATE DATABASE statement is used to create a new database and the files used to store the database.

CREATE DEFAULT

The CREATE DEFAULT statement is used to create an object called a default.

CREATE FUNCTION

The CREATE FUNCTION statement is used to create a user-defined function, which is a saved Transact-SQL routine that returns a value.

CREATE PROCEDURE

The CREATE PROCEDURE statement is used to create a stored procedure, which is a saved collection of Transact-SQL statements.

CREATE RULE

The CREATE RULE statement is used to create an object called a rule.

CREATE TABLE

The CREATE TABLE statement is used to create a new table.

CREATE VIEW

The CREATE VIEW statement is used to create an object called a view.

Implied Permissions

These are the permissions granted to the predefined roles (such as fixed server roles or fixed database roles). For example, a member of the db_owner fixed database role has full permissions in the database.

Managing Permissions

You can use the GRANT, DENY, and REVOKE statements to give or take away permission from a user or role.

The GRANT statement is used to give permissions to a user or role. By using the GRANT statement, it is possible to assign permissions to both statements as well as objects. You can use the GRANT statement with the WITH GRANT OPTION clause to permit the user or role receiving the permission to further grant/revoke access to other accounts.

This example grants the SELECT permission on the authors table to Alex

GRANT SELECT ON authors TO Alex

The DENY statement is used to deny a permission from a security account in the current database and prevents the security account from inheriting the permission through its group or role memberships. You can use the DENY statement to deny both statements and objects permissions.

The following example denies the user Alex SELECT permissions to the authors table:

DENY SELECT ON authors TO Alex

The REVOKE statement is used to remove a previously granted or denied permission from a user in the current database. You can use the REVOKE statement to remove both statements and objects permissions. You can specify the GRANT OPTION FOR clause with the REVOKE statement to remove the WITH GRANT OPTION permissions. Therefore, the user will have the objects permissions, but cannot grant the permissions to other users. Specify the CASCADE clause along with the WITH GRANT OPTION clause, if the permissions being revoked were originally granted using the WITH GRANT OPTION setting.

The following example revokes SELECT permissions to the authors table from the user, Alex:

REVOKE SELECT ON authors TO Alex

Use the WITH GRANT OPTION setting very carefully, because in this case users can grant permissions to the objects to other users and it will be more difficult to manage security.

Do not grant the superfluous permissions to the public role, because each database user has the public role’s permissions.

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2 Responses to “Managing Users Permissions on SQL Server”

  1. Frank said

    Take a look at this eWeek article.
    They descibing security explorer from scriptlogic that can be a good answer in sql security permissions management.
    The solution covers managing of sql databases and objects permissions, permissions cloning and backup.

  2. Thanks Frank really it was best article on Eweek..and i could know more about on it.

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