1.3. Creating a Database
The first test to see whether you can access the database server is to try to create a database. A running PostgreSQL server can manage many databases. Typically, a separate database is used for each project or for each user.
Possibly, your site administrator has already created a database for your use. In that case you can omit this step and skip ahead to the next section.
To create a new database, in this example named
, you use the following command:
If this produces no response then this step was successful and you can skip over the remainder of this section.
If you see a message similar to:
createdb: command not found
then PostgreSQL was not installed properly. Either it was not installed at all or your shell's search path was not set to include it. Try calling the command with an absolute path instead:
The path at your site might be different. Contact your site administrator or check the installation instructions to correct the situation.
Another response could be this:
createdb: could not connect to database postgres: could not connect to server: No such file or directory Is the server running locally and accepting connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
This means that the server was not started, or it was not started
expected it. Again, check the
installation instructions or consult the administrator.
Another response could be this:
createdb: could not connect to database postgres: FATAL: role "joe" does not exist
where your own login name is mentioned. This will happen if the
administrator has not created a
for you. (
user accounts are distinct from
operating system user accounts.) If you are the administrator, see
for help creating accounts. You will need to
become the operating system user under which
was installed (usually
) to create the first user
account. It could also be that you were assigned a
user name that is different from your
operating system user name; in that case you need to use the
switch or set the
environment variable to specify your
If you have a user account but it does not have the privileges required to create a database, you will see the following:
createdb: database creation failed: ERROR: permission denied to create database
Not every user has authorization to create new databases. If PostgreSQL refuses to create databases for you then the site administrator needs to grant you permission to create databases. Consult your site administrator if this occurs. If you installed PostgreSQL yourself then you should log in for the purposes of this tutorial under the user account that you started the server as. 
You can also create databases with other names. PostgreSQL allows you to create any number of databases at a given site. Database names must have an alphabetic first character and are limited to 63 bytes in length. A convenient choice is to create a database with the same name as your current user name. Many tools assume that database name as the default, so it can save you some typing. To create that database, simply type:
If you do not want to use your database anymore you can remove it.
For example, if you are the owner (creator) of the database
, you can destroy it using the following
(For this command, the database name does not default to the user account name. You always need to specify it.) This action physically removes all files associated with the database and cannot be undone, so this should only be done with a great deal of forethought.
As an explanation for why this works:
user names are separate
from operating system user accounts. When you connect to a
database, you can choose what
user name to connect as;
if you don't, it will default to the same name as your current
operating system account. As it happens, there will always be a
user account that has the
same name as the operating system user that started the server,
and it also happens that that user always has permission to
create databases. Instead of logging in as that user you can
also specify the
option everywhere to select
user name to connect as.