Added simple example on golang that using pgx for connect to postgres

examples/golang/cource/06g_databases/db_types.txt

@@ -0,0 +1,10 @@
+Relational DataBase Management System (RDBMS): PostgreSQL, MySQL, Oracle
+Document-oriented NoSQL database: MongoDB, CouchDB
+Key-Value store: Redis, etcd, memcached
+Wide database: 
+  Column-oriented database management system: Clickhouse
+  Row-oriented storage: Cassandra
+Search database: Solr, Splunk, ElasticSearch
+Graph Database management: Neo4j, Virtuoso, OrientDB
+Time seried database: TimescaleDB, Influx, Prometheus
+Etc: GeoMesa, QLDB, SpaceTime, SparkleDB

examples/golang/cource/06g_databases/docker-compose.yml

@@ -0,0 +1,25 @@
+version: '3.1'
+
+services:
+  sql-db:
+    image: postgres
+    restart: always
+    environment:
+      POSTGRES_PASSWORD: some
+    ports:
+      - "5432:5432"
+
+  key-db:
+    image: redis
+    restart: always
+    ports:
+      - "6379:6379"
+
+  no-sql:
+    image: mongo
+    restart: always
+    environment:
+      MONGO_INITDB_DATABASE: master
+      MONGO_INITDB_ROOT_USERNAME: root
+      MONGO_INITDB_ROOT_PASSWORD: some 
+

examples/golang/cource/06g_databases/go.mod

@@ -0,0 +1,21 @@
+module 06g_databases
+
+go 1.23.2
+
+require (
+	github.com/georgysavva/scany v1.2.2
+	github.com/jackc/pgx/v4 v4.18.3
+)
+
+require (
+	github.com/jackc/chunkreader/v2 v2.0.1 // indirect
+	github.com/jackc/pgconn v1.14.3 // indirect
+	github.com/jackc/pgio v1.0.0 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgproto3/v2 v2.3.3 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a // indirect
+	github.com/jackc/pgtype v1.14.0 // indirect
+	github.com/jackc/puddle v1.3.0 // indirect
+	golang.org/x/crypto v0.20.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+)

examples/golang/cource/06g_databases/postgres.go

@@ -0,0 +1,35 @@
+package main
+// GORM
+// https://github.com/jackc/pgx
+
+import (
+	"fmt"
+	"context"
+	"os"
+	"github.com/jackc/pgx/v4"
+//	"github.com/jackc/pgx/v4/pgxpool"
+//	"github.com/georgysavva/scany/pgxscan"
+)
+
+func PostgresSimpleQuery() (name string, position string) {
+	var id int64
+	ctx := context.Background()
+
+	conn, err := pgx.Connect(ctx, "postgres://postgres:some@localhost:5432/postgres")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Can't connect to db: %v\n", err)
+		os.Exit(1)
+	}
+	defer conn.Close(ctx)
+
+	err = conn.QueryRow(ctx, "select * from users where id=$1", 2).Scan(&id, &name, &position)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Query faild: %v\n", err)
+		os.Exit(1)
+	}
+	return name, position
+}
+
+func main() {
+	fmt.Println(PostgresSimpleQuery())
+}

examples/golang/cource/06g_databases/postgres.sql

@@ -0,0 +1,49 @@
+CREATE TABLE users (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(255),
+    rank VARCHAR(255)
+);
+
+CREATE UNIQUE INDEX users_id_uindex ON cars(id);
+
+CREATE TABLE cars (
+    id SERIAL PRIMARY KEY,
+    user_id INT,
+    colour VARCHAR(255),
+    brand VARCHAR(255),
+    license_plate VARCHAR(255),
+    FOREIGN KEY (user_id) REFERENCES users(id)
+);
+
+CREATE UNIQUE INDEX cars_id_uindex ON cars(id);
+
+INSERT INTO users (name, rank) VALUES
+('Alice Johnson', 'Manager'),
+('Bob Smith', 'Developer'),
+('Charlie Brown', 'Designer'),
+('Diana Prince', 'Marketing Specialist'),
+('Ethan Hunt', 'Sales Representative'),
+('Fiona Apple', 'HR Specialist'),
+('George Lucas', 'Project Manager'),
+('Hannah Montana', 'Data Analyst'),
+('Ian Malcolm', 'Customer Support'),
+('Jane Doe', 'Finance Officer');
+
+INSERT INTO cars (user_id, colour, brand, license_plate) VALUES
+(1, 'Red', 'Toyota', 'A1B2C3'),
+(1, 'Yellow', 'Mercedes', 'S9T0U1'),
+(2, 'Blue', 'Honda', 'D4E5F6'),
+(2, 'Purple', 'Audi', 'V2W3X4'),
+(3, 'Green', 'Ford', 'G7H8I9'),
+(3, 'Orange', 'Volkswagen', 'Y5Z6A7'),
+(4, 'Black', 'Chevrolet', 'J0K1L2'),
+(4, 'Pink', 'Hyundai', 'B8C9D0'),
+(5, 'White', 'Nissan', 'M3N4O5'),
+(5, 'Brown', 'Kia', 'E1F2G3'),
+(6, 'Silver', 'BMW', 'P6Q7R8'),
+(6, 'Gray', 'Subaru', 'H4I5J6'),
+(7, 'Red', 'Porsche', 'K7L8M9'),
+(8, 'Blue', 'Tesla', 'N0O1P2'),
+(9, 'Green', 'Mazda', 'Q3R4S5');
+
+