MySQL

The mysql adapter for MySQL wraps the github.com/go-sql-driver/mysql driver written by Julien Schmidt.

Basic use

This page showcases the particularities of the MySQL adapter, if you’re new to upper-db, you should take a look at the getting started page first.

After you’re done with the introduction, reading through the examples is highly recommended.

Installation

Use go get to download and install the adapter:

go get upper.io/db.v3/mysql

Setting up database access

The mysql.ConnectionURL{} struct is defined as follows:

// ConnectionURL implements a MySQL connection struct.
type ConnectionURL struct {
  User     string
  Password string
  Host     string
  Database string
  Options  map[string]string
}

Pass the mysql.ConnectionURL value as argument for mysql.Open() to create a mysql.Database session.

settings = mysql.ConnectionURL{
  ...
}

sess, err = mysql.Open(settings)
...

A mysql.ParseURL() function is provided to convert a DSN into a mysql.ConnectionURL:

// ParseURL parses a DSN into a ConnectionURL struct.
mysql.ParseURL(dsn string) (ConnectionURL, error)

Usage

Import the upper.io/db.v3/mysql package into your application:

// main.go
package main

import (
  "upper.io/db.v3/mysql"
)

Then, you can use the mysql.Open() method to create a session:

var settings = mysql.ConnectionURL{
  Host:     "localhost",  // MySQL server IP or name.
  Database: "peanuts",    // Database name.
  User:     "cbrown",     // Optional user name.
  Password: "snoopy",     // Optional user password.
}

sess, err = db.Open(mysql.Adapter, settings)

Example

The following SQL statement creates a birthday table with name and born columns.

--' example.sql
DROP TABLE IF EXISTS birthday;

CREATE TABLE birthday (
  `name` VARCHAR(50),
  `born` DATE
);

Use the mysql command line tool to create the birthday table into the upperio_tests database.

cat example.sql | mysql -uupperio -pupperio upperio_tests

The Go code below will add some rows to the birthday table and it then will print the same rows that were inserted.

// example.go

package main

import (
  "fmt"
  "log"
  "time"
  "upper.io/db.v3/mysql"   // Imports the mysql adapter.
)

var settings = mysql.ConnectionURL{
  Database: `upperio_tests`,
  Host:     `localhost,`
  User:     `upperio`,
  Password: `upperio`,
}

type Birthday struct {
  // Maps the "Name" property to the "name" column
  // of the "birthday" table.
  Name string `db:"name"`
  // Maps the "Born" property to the "born" column
  // of the "birthday" table.
  Born time.Time `db:"born"`
}

func main() {

  // Attemping to establish a connection to the database.
  sess, err := mysql.Open(settings)
  if err != nil {
    log.Fatalf("db.Open(): %q\n", err)
  }
  defer sess.Close() // Remember to close the database session.

  // Pointing to the "birthday" table.
  birthdayCollection := sess.Collection("birthday")

  // Attempt to remove existing rows (if any).
  err = birthdayCollection.Truncate()
  if err != nil {
    log.Fatalf("Truncate(): %q\n", err)
  }

  // Inserting some rows into the "birthday" table.
  birthdayCollection.Insert(Birthday{
    Name: "Hayao Miyazaki",
    Born: time.Date(1941, time.January, 5, 0, 0, 0, 0, time.UTC),
  })

  birthdayCollection.Insert(Birthday{
    Name: "Nobuo Uematsu",
    Born: time.Date(1959, time.March, 21, 0, 0, 0, 0, time.UTC),
  })

  birthdayCollection.Insert(Birthday{
    Name: "Hironobu Sakaguchi",
    Born: time.Date(1962, time.November, 25, 0, 0, 0, 0, time.UTC),
  })

  // Let's query for the results we've just inserted.
  var res db.Result
  res = birthdayCollection.Find()

  // Query all results and fill the birthdays variable with them.
  var birthdays []Birthday

  err = res.All(&birthdays)
  if err != nil {
    log.Fatalf("res.All(): %q\n", err)
  }

  // Printing to stdout.
  for _, birthday := range birthdays {
    fmt.Printf("%s was born in %s.\n",
      birthday.Name,
      birthday.Born.Format("January 2, 2006"),
    )
  }
}

Running the example above:

go run main.go

gives the following output:

Hayao Miyazaki was born in January 5, 1941.
Nobuo Uematsu was born in March 21, 1959.
Hironobu Sakaguchi was born in November 25, 1962.

Unique adapter features

SQL builder

You can use the query builder for any complex SQL query:

q := b.Select(
    "p.id",
    "p.title AD publication_title",
    "a.name AS artist_name",
  ).From("artists AS a", "publication AS p").
  Where("a.id = p.author_id")

var publications []Publication
if err = q.All(&publications); err != nil {
  log.Fatal(err)
}

Auto-incremental keys

If you want to use auto-increment keys with a MySQL database, you must define the column type as NOT NULL AUTO_INCREMENT, like this:

CREATE TABLE foo(
  id BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT, PRIMARY KEY(id),
  title VARCHAR(255)
);

Remember to set the omitempty option to the ID field:

type Foo struct {
  ID    int64   `db:"id,omitempty"`
  Title string  `db:"title"`
}

Using db.Raw and db.Func

If you need to provide a raw parameter for a method you can use the db.Raw function. Plese note that raw means that the specified value won’t be filtered:

res = sess.Find().Select(db.Raw("DISTINCT(name)"))

db.Raw also works for condition values.

Another useful type that you could use to create an equivalent statement is db.Func:

res = sess.Find().Select(db.Func("DISTINCT", "name"))