Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Programming
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Databases
Mail Systems
openSolaris
Eclipse Documentation
Techotopia.com
Virtuatopia.com

How To Guides
Virtualization
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Windows
Problem Solutions
Privacy Policy

  




 

 

Databases - Practical PostgreSQL
Previous Page Home Next Page

Associating Users with Groups

Users are both added and removed from groups in PostgreSQL through the ALTER GROUP SQL command. Here is the syntax for the ALTER GROUP command:

  ALTER GROUP 
groupname
 { ADD | DROP } USER 
username
 [, ... ]

The groupname is the name of the group to be modified, while the username is the name of the user to be added or removed, depending on whether the ADD or DROP keyword is specified.

Adding a user to a group

Suppose that Booktown hires two new sales associates, David and Ben, and gives them usernames david and ben, respectively. Example 10-14 uses the ALTER GROUP command adds these new users to the sales group.

Example 10-14. Adding a user to a group

booktown=# 
ALTER GROUP sales ADD USER david, ben;

ALTER GROUP

The ALTER GROUP server message returned in Example 10-14 indicates that the users david and ben were successfully added to the sales group. Example 10-15 demonstrates another query to the pg_ group table to verify the addition of those new users to the group. Note that there are now four system IDs in the grolist column for the sales group.

Example 10-15. Verifying user addition

booktown=# 
SELECT * FROM pg_group WHERE groname = 'sales';

 groname | grosysid |        grolist
---------+----------+-----------------------
 sales   |        1 | {7019,7018,7017,7016}
(1 row)

Removing a user from a group

Suppose that some time later David is transferred from sales to accounting. In order to maintain the correct group association, and to make sure that David does not have any rights granted exclusively to the sales group, his user (david) should be removed from that group; Example 10-16 achieves this.

Example 10-16. Removing a user from a group

booktown=# 
ALTER GROUP sales DROP USER david;

ALTER GROUP

The ALTER GROUP message returned from Example 10-16 indicates that the david user was successfully removed from the sales group.

To complete his transition to the accounting department, David must then have his user added to the accounting group. The following statements use similar syntax as the statements in Example 10-14 and Example 10-15. The net effect is that the david user is added into the accounting group. This means that any special rights granted to this group will be implicitly granted to david for as long as he is a member of the group.

booktown=# 
ALTER GROUP accounting ADD USER david;

ALTER GROUP
booktown=# 
SELECT * FROM pg_group;

  groname   | grosysid |     grolist
------------+----------+------------------
 sales      |        1 | {7016,7017,7019}
 accounting |        2 | {7018}
(2 rows)
Databases - Practical PostgreSQL
Previous Page Home Next Page

 
 
  Published under the terms of the Open Publication License Design by Interspire