Building on Hello World. Lets add a Database connection to MySQL

app.go

package main
 
import (
  "database/sql"                     // Needs the mysql driver so we can connect to the DB.
  "net/http"
  "log"

  _ "github.com/go-sql-driver/mysql" // Importing mysql driver for its side-effects, no implicit use
  "github.com/gorilla/mux"
)

var db *sql.DB // Our global to be used in the app for making queries.
 
func main() {
  
  // Setup all of our Database connections
  setupDB()

  r := mux.NewRouter()
  r.HandleFunc("/{name[a-zA-Z]+}", RootHandler).Methods("GET") // Restricts "/:name" to only allow GETs
  http.Handle("/", r)
  http.ListenAndServe(":8080", nil)
}

// Load up the database
func setupDB() {
  var err error
  db, err = sql.Open("mysql", "root@unix(/tmp/mysql.sock)/yourdb") // Does not open a connection
  if err != nil {
    log.Fatalf("Error connecting to the DB: %s", err.Error())
  }
  
  db.SetMaxIdleConnections(10) // Configurable to whatever you'd like
  
  err = db.Ping() // Check for DB access & actually opens the connection!
  if err != nil {
    log.Fatalf("Error connecting to the DB: %s", err.Error())
  }
  
}
 
func RootHandler(w http.ResponseWriter, r *http.Request) {
  params := mux.Vars(r) // Parses the variables in URLS for extraction
  name := params["name"]
  hello := fmt.Sprintf("Hello, %s", name);
  fmt.Fprintln(w, hello) // Prints as text/plain; More magic is needed for JSON
}