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# Postgres

## Installing postgres

```sh
sudo sh -c 'echo "deb https://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update
sudo apt-get -y install postgresql
```

check if server is running

```sh
systemctl status postgresql
```

## First Steps

Log into the database with `sudo -u postgres psql` Log into a remote database with passwordenv variables

```bash
export PGUSER="myuser"
export PGHOST="myhost"
export PGPASSWORD="mypassword"
export PGDATABASE="mydb"
psql
```

or password prompt

```bash
psql -h $POSTGRES_HOST -U $POSTGRES_USER -d $POSTGRES_DATABASE
```

## Postgres shorts

List all tables `\dt` List all [users](https://www.postgresql.org/docs/17/app-psql.html#APP-PSQL-META-COMMAND-DU) `\duS+` See info for table `\d tablename` List all databases `\l` or `list` Switch to database `\c <database>`

## Network access

in `/etc/postgresql/14/main/postgresql.conf` add the \* so postgres listens on all IPs.

```bash
listen_addresses = '*'
```

and in `/etc/postgresql/14/main/pg_hba.conf` add this line add the permissions that users can access the database from any IP

```bash
host    all             all             0.0.0.0/0               md5
```

## Find all Users and there rights/roles

```sql
SELECT u.usename AS "Role name",
  CASE WHEN u.usesuper AND u.usecreatedb THEN CAST('superuser, create
database' AS pg_catalog.text)
       WHEN u.usesuper THEN CAST('superuser' AS pg_catalog.text)
       WHEN u.usecreatedb THEN CAST('create database' AS
pg_catalog.text)
       ELSE CAST('' AS pg_catalog.text)
  END AS "Attributes"
FROM pg_catalog.pg_user u
ORDER BY 1;
```

This has to go into a Postgres Section

```sql
SELECT relname, A.attname FROM pg_class C, pg_namespace N, pg_attribute A, 
pg_type T WHERE (C.relkind=`r') AND (N.old=C.relnamespace) AND 
(A.attrelid=C.old) AND (A.atttypid=T.old) AND (A.attnum>0) AND (NOT A.attisdropped) AND (N.nspname ILIKE `public');
```


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