connection.go

package main

import (
	"database/sql"
	"fmt"
	"github.com/go-sql-driver/mysql"
	"log"
	"os"
)

var db *sql.DB

type Album struct {
	ID       int64
	Title    string
	Artist   string
	Price    float32
	Quantity int64
}

func main() {
	// Capture connection properties.
	cfg := mysql.Config{
		User:   os.Getenv("DBUSER"),
		Passwd: os.Getenv("DBPASS"),
		Net:    "tcp",
		Addr:   "127.0.0.1:3306",
		DBName: "recordings",
	}
	// Get a database handle.
	var err error
	db, err = sql.Open("mysql", cfg.FormatDSN())
	if err != nil {
		log.Fatal(err)
	}

	pingErr := db.Ping()
	if pingErr != nil {
		log.Fatal(pingErr)
	}
	fmt.Println("Connected!")

	// Inserting data
	
	//albID, err := addAlbum(Album{
	//	Title:    "The Modern Sound of Betty Carter",
	//	Artist:   "Betty Carter",
	//	Price:    49.99,
	//	Quantity: 10,
	//})
	//if err != nil {
	//	log.Fatal(err)
	//}
	//fmt.Printf("ID of added album: %v\n", albID)

	// Querying a single row.
	
	//alb, err := albumByID(2)
	//if err != nil {
	//	log.Fatal(err)
	//}
	//fmt.Printf("Album found: %v\n", alb)

	// Querying Multiple Rows

	albums, err := albumsByArtist("John Coltrane")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("Albums found: %v\n", albums)

	// Using Prepared Statements

	// Working with Transactions

}

insert.go

package main

import "fmt"

// addAlbum adds the specified album to the database,
// returning the album ID of the new entry
func addAlbum(alb Album) (int64, error) {
	result, err := db.Exec("INSERT INTO album (title, artist, price, quantity) VALUES (?, ?, ?, ?)", alb.Title, alb.Artist, alb.Price, alb.Quantity)
	if err != nil {
		return 0, fmt.Errorf("addAlbum: %v", err)
	}
	id, err := result.LastInsertId()
	if err != nil {
		return 0, fmt.Errorf("addAlbum: %v", err)
	}
	return id, nil
}

multiple.go

package main

import "fmt"

// albumsByArtist queries for albums that have the specified artist name.
func albumsByArtist(name string) ([]Album, error) {
	// An albums slice to hold data from returned rows.
	var albums []Album

	rows, err := db.Query("SELECT * FROM album WHERE artist = ?", name)
	if err != nil {
		return nil, fmt.Errorf("albumsByArtist %q: %v", name, err)
	}
	defer rows.Close()
	// Loop through rows, using Scan to assign column data to struct fields.
	for rows.Next() {
		var alb Album
		if err := rows.Scan(&alb.ID, &alb.Title, &alb.Artist, &alb.Price, &alb.Quantity); err != nil {
			return nil, fmt.Errorf("albumsByArtist %q: %v", name, err)
		}
		albums = append(albums, alb)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("albumsByArtist %q: %v", name, err)
	}
	return albums, nil
}

single.go

package main

import (
	"database/sql"
	"fmt"
)

// albumByID queries for the album with the specified ID.
func albumByID(id int64) (Album, error) {
	// An album to hold data from the returned row.
	var alb Album

	row := db.QueryRow("SELECT * FROM album WHERE id = ?", id)
	if err := row.Scan(&alb.ID, &alb.Title, &alb.Artist, &alb.Price, &alb.Quantity); err != nil {
		if err == sql.ErrNoRows {
			return alb, fmt.Errorf("albumsById %d: no such album", id)
		}
		return alb, fmt.Errorf("albumsById %d: %v", id, err)
	}
	return alb, nil
}