MySQL

golang/go SQLDrivers

This section borrows heavily from Tutorial: Accessing a relational database. For information about transactions, query cancellation, and connection pools, see Accessing a relational database.

Import the driver

1. Go to SQLDrivers and locate the go-sql-driver/mysql link.

2. In the go file that runs SQL code, import the driver. Because you are not using the driver directly, import it with the blank identifier:

   package main
   
   import "_ github.com/go-sql-driver/mysql"
   

   Use the blank identifier because you do not use any methods from the mysql driver–you use only the driver’s init() function so the driver can register itself with the database/sql package.

3. If you have not installed the package dependency, run go get in the shell:

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

   This installs the latest version of the driver.

Get a database connection pool

To get a database connection pool, you need to provide a database source name (DSN) to the sql package’s Open() function. The Open() function returns a pool of many conncurrent database connections. Go opens and closes these connections through the database driver, as needed.

The DSN is different for each driver. The mysql driver has a parseTime=true option, which tells the driver to convert SQL TIME and DATE to Go time.Time objects.

The database connection pool should be long-lived and passed among handlers, so implement it in the main method. Include a flag for the dsn so you can easily use a different data source. In addition, include a helper function to encapsulate the database connection code:

func main() {

	dsn := flag.String("dsn", "web:pass@/snippetbox?parseTime=true", "MySQL data source name")

	...

    db, err := openDB(*dsn)
    if err != nil {
        errorLog.Fatal(err)
    }
    defer db.Close()

	...
}

func openDB(dsn string) (*sql.DB, error) {
	// sql.Open(driver-name, DSN) {...}
    db, err := sql.Open("mysql", dsn)
    if err != nil {
        return nil, err
    }
    // Connections are created lazily (as needed), so
    // ping the db to establish a connection and confirm 
    // everything is working.
    if err = db.Ping(); err != nil {
        return nil, err
    }
    return db, nil
}