POSTGRE SQL

 PostgreSQL is a powerful object-relational database management system, provided under a flexible BSD-style license.[1] PostgreSQL contains many advanced features, is very fast and standards compliant. PostgreSQL has bindings for many programming languages such as
 C, C++, Python, Java, PHP, Ruby... It can be used to power anything from simple web applications to massive databases with millions of records. Client Installation If you only wish to connect to a PostgreSQL server, do not install the whole PostgreSQL package, but install the PostgreSQL client instead. To do this, use the following command sudo apt-get install postgresql-client you then connect to the server with the following command psql -h server.domain.org database user After you inserted the password you access PostgreSQL with line commands. You may for instance insert the following SELECT * FROM table WHERE 1; You exit the connection with \q Installation Dapper To install PostgreSQL 8.1 you may use the command line and type: sudo apt-get install postgresql-8.1 Hardy Install the latest Postgresql 8.3 from the command line with the following command: sudo apt-get install postgresql Karmic, Lucid, Intrepid and Maverick To install Postgresql 8.4 you may use the command line and type: sudo apt-get install postgresql Administration pgAdmin III is a handy GUI for PostgreSQL, it is essential to beginners. To install it, type at the command line: sudo apt-get install pgadmin3 You may also use the Synaptic package manager from the System>Administration menu to install these packages. Basic Server Setup To start off, we need to change the PostgreSQL postgres user password; we will not be able to access the server otherwise. As the “postgres” Linux user, we will execute the psql command. In a terminal, type: Dapper
 sudo -u postgres psql template1 
 Karmic, Lucid, Intrepid and Maverick
 sudo -u postgres psql postgres 
Set a password for the "postgres" database role using the command:
 \password postgres and give your password when prompted. The password text will be hidden from the console for security purposes. Type Control+D to exit the posgreSQL prompt. Create database To create the first database, which we will call "mydb", simply type:
 sudo -u postgres createdb mydb
Install Server Instrumentation for Postgresql 8.4 To install Server Instrumentation for Postgresql 8.4 you may use the command line and type: sudo apt-get install postgresql-contrib Run the adminpack.sql script, simply type:
 sudo -u postgres psql < /usr/share/postgresql/8.4/contrib/adminpack.sql Alternative Server Setup If you don't intend to connect to the database from other machines, this alternative setup may be simpler. By default in Ubuntu, Postgresql is configured to use 'ident sameuser' authentication for any connections from the same machine. Check out the excellent Postgresql documentation for more information, but essentially this means that if your Ubuntu username is 'foo' and you add 'foo' as a Postgresql user then you can connect to the database without requiring a password. Since the only user who can connect to a fresh install is the postgres user, here is how to create yourself a database account (which is in this case also a database superuser) with the same name as your login name and then create a password for the user:
 sudo -u postgres createuser --superuser
$USER sudo -u postgres psql postgres=# \password $USER Client programs, by default, connect to the local host using your Ubuntu login name and expect to find a database with that name too. So to make things REALLY easy, use your new superuser privileges granted above to create a database with the same name as your login name: createdb $USER Connecting to your own database to try out some SQL should now be as easy as: psql Creating additional database is just as easy, so for example, after running this: create database amarokdb; You can go right ahead and tell Amarok to use postgresql to store its music catalog. The database name would be amarokdb, the username would be your own login name, and you don't even need a password thanks to 'ident sameuser' so you can leave that blank. Using pgAdmin III GUI To get an idea of what PostgreSQL can do, you may start by firing up a graphical client. In a terminal type : pgadmin3 You will be presented with the pgAdmin III interface. Click on the "Add a connection to a server" button (top left). In the new dialog, enter the address 127.0.0.1, a description of the server, the default database ("mydb" in the example above), your username ("postgres") and your password. With this GUI you may start creating and managing databases, query the database, execute SQl etc. Managing the Server Managing users and rights To manage users, you first have to edit /etc/postgresql/8.1/main/pg_hba.conf and modify the default configuration which is very protective. For example, if you want postgres to manage its own users (not linked with system users), you will add the following line: 8<------------------------------------------- # TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD host all all 10.0.0.0 255.255.255.0 md5 8<------------------------------------------- Which means that on your local network (10.0.0.0/24 - replace with your own local network !), postgres users can connect through the network to the database providing a classical couple user / password. Besides allowing a user to connect over the network to the to a database on the server, you must enable postgre to listen across different networks. To do that, open up /etc/postgresql/8.3/main/postgresql.conf in your favourite editor and alter the listen_addresses as below: listen_addresses = '10.0.0.1,localhost' where 10.0.0.1 describes the server's IP address on the local network. Note that this setting is commented out by default. To create a database with a user that have full rights on the database, use the following command:
 sudo -u postgres createuser -D -A -P myuser 
sudo -u postgres createdb -O myuser mydb
 The first command line creates the user with no database creation rights (-D) with no add user rights -A) and will prompt you for entering a password (-P). The second command line create the database 'mydb with 'myuser' as owner. This little example will probably suit most of your needs. For more details, please refer to the corresponding man pages or the online documentation. restarting the server After configuring the networking / users you may need to restart the server, here is a suggested command to do so. sudo /etc/init.d/postgresql-8.3 restart