Question

One of the most asked questions I get about web development in Go is how to connect to a SQL database. Thankfully, Go has a fantastic SQL package in the standard library that allows us to use a whole slew of drivers for different SQL databases. In this example we will connect to a SQLite database, but the syntax (minus some small SQL semantics) is the same for a MySQL or PostgreSQL database.

package main

import (
  "database/sql"
  "fmt"
  "log"
  "net/http"

  _ "github.com/mattn/go-sqlite3"
)

func main() {
  db := NewDB()
  log.Println("Listening on :8080")
  http.ListenAndServe(":8080", ShowBooks(db))
}

func ShowBooks(db *sql.DB) http.Handler {
  return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
    var title, author string
    err := db.QueryRow("select title, author from books").Scan(&title, &author)
    if err != nil {
      panic(err)
    }

    fmt.Fprintf(rw, "The first book is '%s' by '%s'", title, author)
  })
}

func NewDB() *sql.DB {
  db, err := sql.Open("sqlite3", "example.sqlite")
  if err != nil {
    panic(err)
  }

  _, err = db.Exec("create table if not exists books(title text, author text)")
  if err != nil {
    panic(err)
  }

  return db
}

Exercises

1. Make use of the Query function on our sql.DB instance to extract a collection of rows and map them to structs.
2. Add the ability to insert new records into our database by using an HTML form.
3. go get github.com/jmoiron/sqlx and observe the improvements made over the existing database/sql package in the standard library.