Add postgres usage

topics/server/postgres/_posts/2023-10-13-postgresql-installation.md

@@ -1,6 +1,6 @@
 ---
 layout: post
-title: PostgreSql - Installation, Configuration, Operations
+title: PostgreSql - Installation, Configuration, Usage
 author: Ralf Eichinger
 toc: true
 ---
@@ -15,19 +15,94 @@ toc: true
 
 ## Ubuntu 23.04
 
-```
-$ sudo apt-cache search postgresql
+```shell
+$ sudo apt-cache search postgresql | sort | grep postgresql
 ...
 postgresql - Objektrelationale SQL-Datenbank (unterstützte Version)
 ...
+postgresql-15 - Die weltweit fortschrittlichste relationale Open-Source-Datenbank
+...
 $ sudo apt install postgresql
 ```
 
 Test:
 
-```
+```shell
 $ sudo su - postgres
-$ psql --version
+postgres$ psql --version
 psql (PostgreSQL) 15.4 (Ubuntu 15.4-0ubuntu0.23.04.1)
-$
 ```
+
+# Configuration
+
+no configuration changes needed, yet.
+
+# Usage
+
+## Create an user for a database
+
+```sh
+$ sudo su - postgres
+postgres$ psql -c "CREATE USER cudami PASSWORD 'somepassword';"
+CREATE ROLE
+```
+
+## Create a database
+
+Let's create a database called "alexandria", owned by user "cudami" using german locale and collation (see <https://www.postgresql.org/docs/15/collation.html>).
+
+    The collation feature allows specifying the sort order and character classification behavior of data per-column, or even per-operation.
+    This alleviates the restriction that the LC_COLLATE and LC_CTYPE settings of a database cannot be changed after its creation.
+
+Locales of your system:
+
+```shell
+$ locale -a
+C
+C.utf8
+...
+de_DE.utf8
+...
+en_US.utf8
+en_ZA.utf8
+en_ZM
+en_ZM.utf8
+en_ZW.utf8
+POSIX
+```
+
+Create database (see <https://www.postgresql.org/docs/15/app-createdb.html>):
+
+```shell
+$ sudo su - postgres
+(postgres$ dropdb 'alexandria')
+postgres$ createdb alexandria -O cudami --lc-collate=de_DE.UTF-8 --lc-ctype=de_DE.UTF-8
+```
+
+## List databases
+
+```sh
+postgres$ psql -l
+                                                  List of databases
+    Name    |  Owner   | Encoding |   Collate   |    Ctype    | ICU Locale | Locale Provider |   Access privileges   
+------------+----------+----------+-------------+-------------+------------+-----------------+-----------------------
+ alexandria | cudami   | UTF8     | de_DE.UTF-8 | de_DE.UTF-8 |            | libc            | 
+ postgres   | postgres | UTF8     | de_DE.UTF-8 | de_DE.UTF-8 |            | libc            | 
+ template0  | postgres | UTF8     | de_DE.UTF-8 | de_DE.UTF-8 |            | libc            | =c/postgres          +
+            |          |          |             |             |            |                 | postgres=CTc/postgres
+ template1  | postgres | UTF8     | de_DE.UTF-8 | de_DE.UTF-8 |            | libc            | =c/postgres          +
+            |          |          |             |             |            |                 | postgres=CTc/postgres
+(4 rows)
+```
+
+## Connect to database and list tables
+
+```shell
+postgres$ psql -d alexandria
+psql (15.4 (Ubuntu 15.4-0ubuntu0.23.04.1))
+Type "help" for help.
+
+alexandria=# \d
+Did not find any relations.
+alexandria=# \q
+```