Go Postgres SQL connect and select

main.go

package main

import (
	"database/sql"
	"fmt"
	"os"

	_ "github.com/lib/pq"
)

var db *sql.DB

const (
	dbhost = "DBHOST"
	dbport = "DBPORT"
	dbuser = "DBUSER"
	dbpass = "DBPASS"
	dbname = "DBNAME"
)

type bookSummary struct {
	ID     int
	Title  string
	Author string
	Year   string
}

func main() {

	bs := make([]bookSummary, 0)

	config := dbConfig()
	var err error
	psqlInfo := fmt.Sprintf("host=%s port=%s user=%s "+
		"password=%s dbname=%s sslmode=require",
		config[dbhost], config[dbport],
		config[dbuser], config[dbpass], config[dbname])

	db, err = sql.Open("postgres", psqlInfo)
	if err != nil {
		panic(err)
	}
	err = db.Ping()
	if err != nil {
		panic(err)
	}
	fmt.Println("Successfully connected!")

	rows, err := db.Query(`
	SELECT 
	id, title, author, year 
	FROM 
	books`)
	if err != nil {
		panic(err)
	}
	defer rows.Close()
	for rows.Next() {
		book := bookSummary{}
		err = rows.Scan(
			&book.ID,
			&book.Title,
			&book.Author,
			&book.Year,
		)
		if err != nil {
			panic(err)
		}
		bs = append(bs, book)
	}
	err = rows.Err()
	if err != nil {
		panic(err)
	}

	for _, b := range bs {

		fmt.Printf("    ID : [%d]\n", b.ID)
		fmt.Printf(" Title : [%s]\n", b.Title)
		fmt.Printf("Author : [%s]\n", b.Author)
		fmt.Printf("  Year : [%s]\n\n", b.Year)

	}
}

func dbConfig() map[string]string {
	conf := make(map[string]string)
	host, ok := os.LookupEnv(dbhost)
	if !ok {
		panic("DBHOST environment variable required but not set")
	}
	port, ok := os.LookupEnv(dbport)
	if !ok {
		panic("DBPORT environment variable required but not set")
	}
	user, ok := os.LookupEnv(dbuser)
	if !ok {
		panic("DBUSER environment variable required but not set")
	}
	password, ok := os.LookupEnv(dbpass)
	if !ok {
		panic("DBPASS environment variable required but not set")
	}
	name, ok := os.LookupEnv(dbname)
	if !ok {
		panic("DBNAME environment variable required but not set")
	}
	conf[dbhost] = host
	conf[dbport] = port
	conf[dbuser] = user
	conf[dbpass] = password
	conf[dbname] = name
  
	return conf
}