Connecting with Go

This guide explains how to establish a connection between a Go application and a MySQL database using the go-sql-driver/mysql package. It walks through the necessary setup, configuration, and execution of a simple SQL query.

Variables

Certain parameters must be provided to establish a successful connection to a MySQL database. Below is a breakdown of each required variable, its purpose, and where to find it. Here’s what each variable represents:

These values can usually be found in the Elestio service overview details, as shown in the image below. Make sure to take a copy of these details and add them to the code moving ahead.

Prerequisites

• Install Go
  • Check if Go is installed by running: go version
  • If not installed, download it from golang.org and install.

• Install the MySQL Driver
  • Use the following command to install the go-sql-driver/mysql driver: go get -u github.com/go-sql-driver/mysql

Code

Once all prerequisites are set up, create a new file named mysql_connect.go and add the following code:

package main

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

	_ "github.com/go-sql-driver/mysql"
)

func main() {
	user := "USER"
	password := "PASSWORD"
	host := "HOST"
	port := "PORT"
	database := "DATABASE"

	// Construct DSN (Data Source Name)
	dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s", user, password, host, port, database)

	// Open a connection
	db, err := sql.Open("mysql", dsn)
	if err != nil {
		log.Fatalf("Connection failed: %v", err)
	}
	defer db.Close()

	// Ping to verify connection
	if err := db.Ping(); err != nil {
		log.Fatalf("Ping failed: %v", err)
	}
	fmt.Println("Connected to MySQL")

	// Run a test query to check the MySQL version
	var version string
	err = db.QueryRow("SELECT VERSION()").Scan(&version)
	if err != nil {
		log.Fatalf("Query execution failed: %v", err)
	}
	fmt.Printf("MySQL Version: %s\n", version)
}

To execute the script, open the terminal and navigate to the directory where mysql_connect.go is located. Once in the correct directory, run the script with the commands:

go mod init example.com/mysqlconnect
go run mysql_connect.go

If the connection is successful, the terminal will display output similar to:

Connected to MySQL
MySQL Version: 8.0.36