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Understanding SQL Server Roles

Tuesday Mar 20th 2001 by Alexander Chigrik

In this article, Alexander Chigrik covers the various types of roles in SQL Server 7.0 and provides tips on how you can add new roles, how you can drop existing ones, and how you can return information about the roles.


Introduction
Server Roles
Database Roles
  • Fixed Database Roles
  • Public Role
  • User-Defined Database Roles
Application Roles

 

Introduction

Roles are the new SQL Server 7.0 feature, which was not available in
the previous versions. SQL Server roles act like Windows NT local
groups.

SQL Server 7.0 supports several different types of roles. There are:
  • server roles
  • database roles
  • application roles

In this article, I want to tell you about each kind of roles, about
how you can add new role, how you can drop existing role, how you
can return information about the roles, and so on.

Server Roles

Server roles are defined at the server level and exist outside of users
databases. There are only fixed server roles, so you cannot add, delete
or modify server role. You can only add users as a member of a server
roles.

There are seven fixed server roles:
  • sysadmin
  • serveradmin
  • setupadmin
  • securityadmin
  • processadmin
  • dbcreator
  • diskadmin

The members of sysadmin server role can perform any activity in
SQL Server 7.0 and have completes control over all database functions.

The members of serveradmin server role can change server 
configuration
parameters and shut down the server.

The members of setupadmin server role can manage linked servers (add
or remove linked servers), manage replication, manage extended stored
procedures, and execute some system stored procedures, such as
sp_serveroption.

The members of securityadmin server role can create and manage server
logins and auditing, and read error logs.

The members of processadmin server role can manage the processes
running in SQL Server.

The members of dbcreator server role can create, alter, and resize
databases.

The members of diskadmin server role can manage disk files.


To add a login as a member of a fixed server role, you 
can use
sp_addsrvrolemember system stored procedure.This is the syntax:
sp_addsrvrolemember [@loginame =] 'login', [@rolename =] 'role'
where @loginame - is a SQL Server login or a Windows NT user account. @rolename - is the name of the fixed server role. See this link for more information sp_addsrvrolemember (T-SQL) To remove a SQL Server login or a Windows NT user or group from a fixed server role, you can use sp_dropsrvrolemember system stored procedure.This is the syntax:
sp_dropsrvrolemember [@loginame =] 'login', [@rolename =] 'role'
where @loginame - is the name of a login to remove. @rolename - is the name of the fixed server role. See this link for more information sp_dropsrvrolemember (T-SQL) To return a list of the SQL Server fixed server roles, you can use sp_helpsrvrole system stored procedure.This is the syntax:
sp_helpsrvrole [[@srvrolename =] 'role']
where @srvrolename - is the name of the fixed server role. See this link for more information sp_helpsrvrole (T-SQL)

Database Roles

In SQL Server 6.5 you can use database groups to simplify management
of a large number of database users. For example, you can use database
groups to grant and revoke permissions to more than one user at the
same time.
But database groups are no longer supported in SQL Server 7.0.
SQL Server database roles act like SQL Server 6.5 database groups,
but roles have some improvements: in SQL Server 6.5 each user can be
a member of only one group (in addition to public group), but in
SQL Server 7.0 each user can belong to many roles and the result users
permissions are combined for all roles they're members of.

There are three kinds of the database roles:
  • Fixed Database Roles
  • Public Role
  • User-Defined Database Roles

Fixed Database Roles

Fixed database roles are defined at the database level and exist in
each database.
You cannot add, delete or modify fixed database roles. You can only
add users as a member of a fixed database roles.

There are nine fixed database roles:
  • db_owner
  • db_accessadmin
  • db_datareader
  • db_datawriter
  • db_ddladmin
  • db_securityadmin
  • db_backupoperator
  • db_denydatareader
  • db_denydatawriter

The members of db_owner database role can perform any activity in
the database.

The members of db_accessadmin database role can add or remove Windows 
NT
groups, users or SQL Server users in the database.

The members of db_datareader database role can see any data from all
user tables in the database.

The members of db_datawriter database role can add, change, or delete
data from all user tables in the database.

The members of db_ddladmin database role can make any data definition
language commands in the database.

The members of db_securityadmin database role can manage statement
and object permissions in the database.

The members of db_backupoperator database role can back up the
database.

The members of db_denydatareader database role can deny permission to
select data in the database.

The members of db_denydatawriter database role can deny permission to
change data in the database.


To add a security account as a member of an existing 
SQL Server
database role in the current database, you can use sp_addrolemember
system stored procedure.This is the syntax:
sp_addrolemember [@rolename =] 'role',
    [@membername =] 'security_account'
where @rolename - is the name of the database role. @membername - is the name of the security account. Any member of a fixed database role can add other users to this role. See this link for more information sp_addrolemember (T-SQL) To remove a security account from a SQL Server role in the current database, you can use sp_droprolemember system stored procedure.This is the syntax:
sp_droprolemember [@rolename =] 'role',
    [@membername =] 'security_account'
where @rolename - is the name of the role. @membername - is the name of the security account. See this link for more information sp_droprolemember (T-SQL) To return information about the members of a role in the current database, you can use sp_helprolemember system stored procedure.This is the syntax:
sp_helprolemember [[@rolename =] 'role']
where @rolename - is the name of a role in the current database. See this link for more information sp_helprolemember (T-SQL)

Public Role

The public role is a special database role to which every database
user belongs. The public role contain default access permissions
for any user who can access the database. This database role cannot
be dropped.

User-Defined Database Roles

Although the built-in database roles handle permissions for common
database management tasks, it's likely that you will want to group
users who have access to perform specific database functions.


To create a new SQL Server role in the current 
database, you can use
sp_addrole system stored procedure.This is the syntax:
sp_addrole [@rolename =] 'role' [,[@ownername =] 'owner']
where @rolename - is the name of the database role. @ownername - is the owner of the new role. See this link for more information sp_addrole (T-SQL) To remove a SQL Server role from the current database, you can use sp_droprole system stored procedure.This is the syntax:
sp_droprole [@rolename =] 'role'
where @rolename - is the name of the role. See this link for more information sp_droprole (T-SQL)

Application Roles

Application roles are the SQL Server roles created to support the
security needs of an application. Often database applications
enforce their own security based on the application logic.
For example, you can use application role with its own password
to allow the particular user to obtain and modify any data only
during specific hours. So, you can realize more complex security
management within the application logic.


To add a special type of role in the current database, 
which is used
for application security, you can use sp_addapprole stored 
procedure.This is the syntax:
sp_addapprole [@rolename =] 'role', [@password =] 'password'
where @rolename - is the name of the application role. @password - is the password for the new application role. See this link for more information sp_addapprole (T-SQL) To remove an application role from the current database, you can use sp_dropapprole system stored procedure.This is the syntax:
sp_dropapprole [@rolename =] 'role'
where @rolename - is the name of the application role. See this link for more information sp_dropapprole (T-SQL) To change the password of an application role in the current database, you can use sp_approlepassword system stored procedure.This is the syntax:
sp_approlepassword [@rolename =] 'role', [@newpwd =] 'password'
where @rolename - is the name of the application role. @newpwd - is the new password for the application role. See this link for more information sp_approlepassword (T-SQL)


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