How can I connect to a database as another user? - postgresql

Im currently creating an API for a school project and everything is working good. My setup is: Node v10, Postgres, Koa and so on...
I currently have this:
CREATE ROLE sa WITH LOGIN PASSWORD 'some-password.';
CREATE DATABASE master WITH OWNER sa;
\c master;
When the init script runs in the docker machine the output I get is this one:
CREATE ROLE
CREATE DATABASE
You are now connected to database "master" as user "postgres".
So I did change the file to something like this:
CREATE ROLE sa WITH LOGIN PASSWORD 'some-password.';
CREATE DATABASE master WITH OWNER sa;
CONNECT TO master AS main USER sa;
And I get a syntax error:
STATEMENT: CONNECT TO master AS sa USER sa;
psql:/docker-entrypoint-initdb.d/init.sql:4: ERROR: syntax error at or near "CONNECT"
I can't find anywhere in docs (or haven't look very good) how to connect from a .sql file to a database with an specific user.
How would I connect to 'master' with its owner, which is 'sa' from a .sql file?

You can do this via this command in psql:
\c db_name usr_name

Here my assumption is you have a SQL file called "a.sql" and contains the lines of code in the file.
CREATE ROLE sa WITH LOGIN PASSWORD 'some-password.';
CREATE DATABASE master WITH OWNER sa;
\c master;
Now you are running this script using "psql" command line interface (CLI), so you get the message as below...
CREATE ROLE
CREATE DATABASE
You are now connected to database "master" as user "postgres".
Now, the thing to be noted that you have connected to database "master" because of "\c master" with user "postgres" because of you passed the credential of "postgres" user. Is I am right here then, If yes, then you have to pass the user and password for different user i.e. "sa" as below.
psql -h localhost -p 5432 -U sa -f a.sql master
Now, it will prompt for the password of "sa" user, finally, your script will run and you will be connected to "sa" user.

You can do this via this command in terminal
psql -d database -U username

Related

create database user with postgres on azure

I need to create an additional user on postgres running on azure usually I would do :
create user myfineuser with password 'myfinepassword';
grant connect on database myfinedatabase to myfineuser;
But when I then try to connect to the db on azure with
psql "host=myfinehost.postgres.database.azure.com port=5432 \
dbname=myfinedatabase user=myfineuser password=myfinepassword sslmode=require"
I do receive
psql: FATAL: Invalid Username specified. Please check the Username and retry connection. The
Username should be in <username#hostname> format.
I did not fine how to specify user#host in the sql statement to create the user
myfineuser#myfinehost, 'myfineuser#myfinehost', .... all these permutations do result in a syntax error
How can i do this with psql. This article just talks about user but not how to specify user#host https://learn.microsoft.com/da-dk/azure/postgresql/howto-create-users#how-to-create-database-users-in-azure-database-for-postgresql
The solution ist simple :
create user myfineuser with password 'myfinepassword';
grant connect on database myfinedatabase to myfineuser;
then in psql :
psql "host=myfinehost.postgres.database.azure.com port=5432 \
dbname=myfinedatabase user=myfineuser#myfinehost password=myfinepassword sslmode=require"
note the myfineuser#myfinehost in the psql connect string. This is implicit

Username seen as database in psql command?

This question is similar to create database using psql in shell script takes username as db name, but since that doesn't have an accepted answer I'm asking it again here. I've created a user with username myuser and password mypassword:
> psql
psql (11.5)
Type "help" for help.
kurt=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------------------+-----------
kurt | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
myuser | | {}
kurt=#
However, if I do psql --username=myuser, I get an error that database "myuser" does not exist:
> psql --username=myuser
psql: FATAL: database "myuser" does not exist
I'm a bit confused by this error message, because according to psql --help, this is a user name, not a database name:
Connection options:
-h, --host=HOSTNAME database server host or socket directory (default: "local socket")
-p, --port=PORT database server port (default: "5432")
-U, --username=USERNAME database user name (default: "kurt")
-w, --no-password never prompt for password
-W, --password force password prompt (should happen automatically)
Any idea what I'm doing wrong? Here is the version of psql I'm using:
> psql --version
psql (PostgreSQL) 11.5
Quote from the manual
The default user name is your operating-system user name, as is the default database name
If you specify a username, that username is then also assumed as the default for the database name.
After creating your new user, first you have to login using postgres user and create new database similar to your new created user. ex: if my new user is "david", I must create also database called "david" using posgtres user.After this you can now login using your new user created.

How can I create a Postgres 11 user/role with a different name than the OS-user?

I'm a newbie to PostgreSQL and I'm trying to create a user/role on Postgres 11 (running on CentOS7) which is named (e.g.) "json_docs_admin" (same for password) that I can use under the OS user (e.g.) "app_user" to connect locally to the DB.
I have tried connecting to Postgres using "postgres" user and the command "psql -d template1" and ran the following commands:
template1=# create role json_docs_admin with login password 'json_docs_admin';
CREATE ROLE
template1=# create database json_docs owner=json_docs_admin;
CREATE DATABASE
template1=# GRANT ALL PRIVILEGES ON DATABASE json_docs TO json_docs_admin;
GRANT
I have changed the /var/lib/pgsql/11/data/pg_hba.conf so that local connections can be established on the server, and I've restarted the postgresql service.
Then, back under "app_user" user, when I try to connect to the database, I get the following errors:
$psql -d json_docs -U json_docs_admin
Password for user json_docs_admin:
psql: FATAL: database "json_docs" does not exist
Could anybody let me know what am I doing wrong?
Thanks.

createdb: database creation failed: ERROR: permission denied to create database

I am pretty much confused about root user,super user,user and permissions! I am not able to create a database inside user "athleticu". Following are the commands I used:-
athleticu#ip-172-30-4-103:/home/ubuntu$ createdb -T template0 simple_db1
createdb: database creation failed: ERROR: permission denied to create database
athleticu#ip-172-30-4-103:/home/ubuntu$ sudo createdb -T template0 simple_db1
sudo: unable to resolve host ip-172-30-4-103
createdb: could not connect to database template1: FATAL: role "root" does not exist
Please somebody clarify my doubts and tell me what should I write!
Hey I have already solved this. What you have to do is to first login as postgres user as follows:
$ su postgres
$ psql
postgres=# alter user athleticu createdb;
ALTER ROLE
Hope it helps you :)
Type \du in psql and you will see a list of all the registered users and what type of privileges each one has.
In order to grant privileges to the user which is logged in (eg 'user1'), I had to sign out and log in using one of the superuser roles in that list (eg. 'user2'), using the following command:
psql -U 'user2' -h localhost 'database2'
where 'database2' is the name of the one that specific superuser 'user2' has privileges to.
Once you are logged in as a superuser, you can grant privileges to 'user1' by:
ALTER ROLE user1 WITH CREATEDB
or
ALTER ROLE user1 WITH SUPERUSER
Then sign in again as user1, who is now a superuser.
This blog was helpful as well as this link.
Currently, this worked for me:
sudo su postgres
psql
ALTER USER username WITH CREATEDB;
\q
exit
The root user is an account on the system independent from Postgres. There is only one root user.
A superuser is an account in Postgres with access to everything. There may be many superusers.
System accounts and Postgres accounts are different things, although unless you specify a Postgres username when you connect to the database (through utilities like psql, createdb, dropdb, or otherwise), it will use the current system user's name in hopes that there is a corresponding Postgres account with the same name. The root user does not, by default, have a corresponding account in Postgres.
When you install Postgres on *nix, it creates both a superuser named postgres and a system user named postgres.
Therefore, when you need to do something with Postgres as the built-in superuser, you have two options:
You may sudo su - postgres to become the postgres system user and execute your command (createdb, psql, etc). Because the system user has the same name as the database superuser, your command will connect as the appropriate account.
You may specify the username to execute as with the -U switch, eg psql -U postgres ....
Depending on your Postgres server's authentication settings, you may be required to enter a password with either or both connection methods.
What you can do when you have fresh installation of PostgreSQL is create your user with some rights (see createuser documentation):
my-user> sudo su - postgres -c "createuser <my-user> --createdb"
This will allow my-user to create DBs just like so:
my-user> createdb <my-db>
If you want the my-user to be able to do anything just use the --superuser flag instead:
my-user> sudo su - postgres -c "createuser <my-user> --superuser"
I got the same error and I found out that the reason was that I was trying to create a database outside of psql as a user which did not exist for postgresql. I found out about it and solved it by taking the following steps:
In my terminal I logged in as postgres user (the root user by default for postgresql) by typing sudo -u postgres psql
While inside the psql I typed \du to see all users and their privileges. I found out that I had only one user (the postgres one) and I had to create another superuser which had the same username as my Linux user (george)
I typed (still inside psql) CREATE USER george SUPERUSER; and this way I created a new super user called george.
I exited psql (by typing \q) and I was now able from outside psql, meaning from my terminal, to run created db <database name> with no issues at all.
Error ? You are trying to perform database actions( Creating Database, creating Roles) using a user that doesn't have the permission for those types of actions you are trying to perform.
solution ? Simply login to your database on the command line, i.e for PostgreSQL one will use "sudo -u postgres psql", then confirm that users specific assigned roles using the command "\du", most probably he/she doesn't have the necessary permissions to perform the actions you wanted. Then simply assign the roles you want the user to perform ,i.e create Database or simply make user "Superuser" by following along(https://chartio.com/resources/tutorials/how-to-change-a-user-to-superuser-in-postgresql/)

PostgreSQL public access to database

I recently created a test database but I would like it to be accessible to all users.
I created the database as user postgres then use the command
GRANT ALL ON DATABASE dbname TO public;
But when I log out and try to connect to it with a different user I get this error
psql -d dbname
psql: FATAL: role "username" does not exist
I don't want to have to create a user for each person who will be accessing the database which is the reason i wanted to make it public. Is there a permission that I am still missing?
Although access to everybody (public) is granted, the user you connect with has to exist. The default for psql is the username of your system account. You can, of course, create a passwordless anonymous user everybody can use to connect:
psql -U anonymous dbname