How to SELECT data from a MySQL database using Golang

A guide on how to use Golang to query data from a MySQL database using Prepared Statements with multiple parameters.

In this article, you will learn how to use Golang to connect to a MySQL database and perform a SELECT query using Prepared Statements with multiple parameters, enhancing both performance and security.

package main

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

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

func main() {
	// Connect to MySQL database
	dsn := "root:password@tcp(127.0.0.1:3306)/test_db"
	db, err := sql.Open("mysql", dsn)
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	// Check connection
	err = db.Ping()
	if err != nil {
		log.Fatal(err)
	}

	// Use Prepared Statement with multi params
	stmt, err := db.Prepare("SELECT id, name, age FROM students WHERE age > ? AND age < ?")
	if err != nil {
		log.Fatal(err)
	}
	defer stmt.Close()

	// Execute the query with parameters
	rows, err := stmt.Query(18, 25)
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()

	// Iterate over the query results
	for rows.Next() {
		var id int
		var name string
		var age int

		err := rows.Scan(&id, &name, &age)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf("ID: %d, Name: %s, Age: %d\n", id, name, age)
	}

	// Check for errors after iterating through rows
	if err = rows.Err(); err != nil {
		log.Fatal(err)
	}
}

Detailed explanation:

1. import: Specifies the necessary packages for the program.
2. sql.Open("mysql", dsn): Opens a connection to the MySQL database using the provided dsn.
3. db.Prepare(...): Creates a Prepared Statement with the SELECT query and placeholders for parameters.
4. stmt.Query(18, 25): Executes the query with the provided parameters.
5. rows.Next(): Iterates over the result set rows.
6. rows.Scan(...): Retrieves data from the current row and assigns it to variables.
7. fmt.Printf: Prints the retrieved data.

System Requirements:

• Golang 1.16+
• MySQL Driver Library: github.com/go-sql-driver/mysql

How to install the libraries needed to run the Golang code above:

Use the following command to install the library:

go get -u github.com/go-sql-driver/mysql

Tips:

• Using Prepared Statements helps prevent SQL Injection and improves performance.
• Always check the database connection before performing any operations.