Most commands are found by \? e.g.
\dt - list tables \l - list databases \c - connect to db \du - list users/roles
Since PostgreSQL 10, psql has \gx which is equal to mysql \G
select * from sometable \gx
Basic User Access
E.g. you are testing a program w/db as a desktop user.
su - postgres createuser --pwprompt user (still as postgres.......) createdb -O user mydb
In psql as postgres you must
ALTER USER user CREATEDB;
otherwise, the user account can't create a db (though he can delete). Finally, as the logged in user account you can:
psql -d postgres -c "DROP DATABASE mydb;" psql -d postgres -c "CREATE DATABASE mydb;"
If you were making a db program with user access, you would do something with roles (Grant (ALL,select,insert,etc) on db/tablename to username)
######## db_create.sh psql -d postgres -c "CREATE DATABASE mydb;" psql -d mydb -c " CREATE TABLE entry ( \ id SERIAL PRIMARY KEY, \ entryvalue TEXT \ );" ######## db_delete.sh psql -d postgres -c "DROP DATABASE mydb;"
I don't understand why sometimes you must specify -d postgres and sometimes you can specify the specific db. In practice, I suppose it isn't important.
Backup / Restore DB
This will run the dump as the postgres user via su, and avoids some of the permissions errors that can creep up.
# cd /tmp (just need a writeable directory, aka 777) # su -c 'pg_dump mydb >> mydb_dump_2020.sql' postgres
assuming you have a postgres admin user, with all rights, this will backup the db. If you are remote, you might need something similar to (localhost/ip, ports, etc specified):
pg_dump -U username -h localhost databasename >> sqlfile.sql
Create the new db:
su - postgres psql create database bbbtest; grant all privileges on database bbbtest to mypguser; ALTER DATABASE bbbtest OWNER TO mypguser;
and postgres permissions are a disaster online for getting info on (unforunately, there is nothing like mysql's mysql -uroot -p -e "grant all on db.* to 'user'@localhost identified by 'pass';"). But what does work is permissions for specific tables need to be enabled for the user, so:
GRANT ALL ON sometableindb TO mypguser; \quit exit
Now, with that file
# su -c 'psql -d newdbname --set ON_ERROR_STOP=on -f ./mydb_dump_2020.sql' postgres
If you get errors, adjust data as needed or remove the ON_ERROR_STOP (some can be ignored, some can not - use discretion). At least in some cases, you can move data without worrying about postgres versions. I executed a pg_dump from 11.# and imported to 9.6 without issue. Devuan Beowulf to Ascii.
TIP: if you don't specify -d, then the data will get uploaded to one of the preexisting DB. Not good.
-- su - postgres -- -- psql -- -- -- create database bbbtest; -- -- -- grant all privileges on database bbbtest to root; -- -- -- \quit -- -- exit -- psql bbbtest < dbmake.sql -- -- select * from A1;
Verify user permissions and upload was correct
su - mypguser psql select * from sometable;
See notes about table permissions above.
Create a user
Note that if you have an existing db, you might want to add ownership to this user, or r/w permissions.
- http://web.archive.org/web/20221129022928/https://blog.frankel.ch/poor-man-api/ - postgres, easy to deploy http api. Note that in golang, there are also quite easy ways to create an http server. Python as well, i'm sure.