Connecting to a Database

GORM officially supports the databases MySQL, PostgreSQL, GaussDB, SQLite, SQL Server TiDB, and Oracle Database

MySQL

import (
  "gorm.io/driver/mysql"
  "gorm.io/gorm"
)

func main() {
  
  dsn := "user:pass@tcp(127.0.0.1:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local"
  db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
}

NOTE:
To handle time.Time correctly, you need to include parseTime as a parameter. (more parameters)
To fully support UTF-8 encoding, you need to change charset=utf8 to charset=utf8mb4. See this article for a detailed explanation

MySQL Driver provides a few advanced configurations which can be used during initialization, for example:

db, err := gorm.Open(mysql.New(mysql.Config{
  DSN: "gorm:gorm@tcp(127.0.0.1:3306)/gorm?charset=utf8&parseTime=True&loc=Local", 
  DefaultStringSize: 256, 
  DisableDatetimePrecision: true, 
  DontSupportRenameIndex: true, 
  DontSupportRenameColumn: true, 
  SkipInitializeWithVersion: false, 
}), &gorm.Config{})

Customize Driver

GORM allows to customize the MySQL driver with the DriverName option, for example:

import (
  _ "example.com/my_mysql_driver"
  "gorm.io/driver/mysql"
  "gorm.io/gorm"
)

db, err := gorm.Open(mysql.New(mysql.Config{
  DriverName: "my_mysql_driver",
  DSN: "gorm:gorm@tcp(localhost:9910)/gorm?charset=utf8&parseTime=True&loc=Local", 
}), &gorm.Config{})

Existing database connection

GORM allows to initialize *gorm.DB with an existing database connection

import (
  "database/sql"
  "gorm.io/driver/mysql"
  "gorm.io/gorm"
)

sqlDB, err := sql.Open("mysql", "mydb_dsn")
gormDB, err := gorm.Open(mysql.New(mysql.Config{
  Conn: sqlDB,
}), &gorm.Config{})

PostgreSQL

import (
  "gorm.io/driver/postgres"
  "gorm.io/gorm"
)

dsn := "host=localhost user=gorm password=gorm dbname=gorm port=9920 sslmode=disable TimeZone=Asia/Shanghai"
db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})

We are using pgx as postgres’s database/sql driver, it enables prepared statement cache by default, to disable it:


db, err := gorm.Open(postgres.New(postgres.Config{
  DSN: "user=gorm password=gorm dbname=gorm port=9920 sslmode=disable TimeZone=Asia/Shanghai",
  PreferSimpleProtocol: true, 
}), &gorm.Config{})

Customize Driver

GORM allows to customize the PostgreSQL driver with the DriverName option, for example:

import (
  _ "github.com/GoogleCloudPlatform/cloudsql-proxy/proxy/dialers/postgres"
  "gorm.io/gorm"
)

db, err := gorm.Open(postgres.New(postgres.Config{
  DriverName: "cloudsqlpostgres",
  DSN: "host=project:region:instance user=postgres dbname=postgres password=password sslmode=disable",
})

Existing database connection

GORM allows to initialize *gorm.DB with an existing database connection

import (
  "database/sql"
  "gorm.io/driver/postgres"
  "gorm.io/gorm"
)

sqlDB, err := sql.Open("pgx", "mydb_dsn")
gormDB, err := gorm.Open(postgres.New(postgres.Config{
  Conn: sqlDB,
}), &gorm.Config{})

GaussDB

import (
  "gorm.io/driver/gaussdb"
  "gorm.io/gorm"
)

dsn := "host=localhost user=gorm password=gorm dbname=gorm port=8000 sslmode=disable TimeZone=Asia/Shanghai"
db, err := gorm.Open(gaussdb.Open(dsn), &gorm.Config{})

We are using gaussdb-go as gaussdb’s database/sql driver, it enables prepared statement cache by default, to disable it:


db, err := gorm.Open(gaussdb.New(gaussdb.Config{
  DSN: "user=gorm password=gorm dbname=gorm port=8000 sslmode=disable TimeZone=Asia/Shanghai",
  PreferSimpleProtocol: true, 
}), &gorm.Config{})

Customize Driver

GORM allows to customize the GaussDB driver with the DriverName option, for example:

import (
  _ "github.com/GoogleCloudPlatform/cloudsql-proxy/proxy/dialers/gaussdb"
  "gorm.io/gorm"
)

db, err := gorm.Open(gaussdb.New(gaussdb.Config{
  DriverName: "cloudsqlgaussdb",
  DSN: "host=project:region:instance user=gaussdb dbname=gaussdb password=password sslmode=disable",
})

Existing database connection

GORM allows to initialize *gorm.DB with an existing database connection

import (
  "database/sql"
  "gorm.io/driver/gaussdb"
  "gorm.io/gorm"
)

sqlDB, err := sql.Open("gaussdbgo", "mydb_dsn")
gormDB, err := gorm.Open(gaussdb.New(gaussdb.Config{
  Conn: sqlDB,
}), &gorm.Config{})

Oracle Database

The GORM Driver for Oracle provides support for Oracle Database, enabling full compatibility with GORM’s ORM capabilities. It is built on top of the Go Driver for Oracle (Godror) and supports key features such as auto migrations, associations, transactions, and advanced querying.

Prerequisite: Install Instant Client

To use ODPI-C with Godror, you’ll need to install the Oracle Instant Client on your system. Follow the steps on this page to complete the installation.

After that, you can connect to the database using the dataSourceName, which specifies connection parameters (such as username and password) using a logfmt-encoded parameter list.

The way you specify the Instant Client directory differs by platform:

macOS and Windows: You can set the libDir parameter in the dataSourceName.
Linux: The libraries must be in the system library search path before your Go process starts, preferably configured with “ldconfig”. The libDir parameter does not work on Linux.

Example (macOS/Windows)

dataSourceName := `user="scott" password="tiger" 
                   connectString="dbhost:1521/orclpdb1"
                   libDir="/Path/to/your/instantclient_23_26"`

Example (Linux)

dataSourceName := `user="scott" password="tiger" 
                   connectString="dbhost:1521/orclpdb1"`

Getting Started

import (
  "github.com/oracle-samples/gorm-oracle/oracle"
  "gorm.io/gorm"
)

dataSourceName := `user="scott" password="tiger"
                   connectString="dbhost:1521/orclpdb1"`
db, err := gorm.Open(oracle.Open(dataSourceName), &gorm.Config{})

SQLite

import (
  "gorm.io/driver/sqlite" 
  
  
  "gorm.io/gorm"
)


db, err := gorm.Open(sqlite.Open("gorm.db"), &gorm.Config{})

NOTE: You can also use file::memory:?cache=shared instead of a path to a file. This will tell SQLite to use a temporary database in system memory. (See SQLite docs for this)

SQL Server

import (
  "gorm.io/driver/sqlserver"
  "gorm.io/gorm"
)


dsn := "sqlserver://gorm:LoremIpsum86@localhost:9930?database=gorm"
db, err := gorm.Open(sqlserver.Open(dsn), &gorm.Config{})

TiDB

TiDB is compatible with MySQL protocol. You can follow the MySQL part to create a connection to TiDB.

There are some points noteworthy for TiDB:

You can use gorm:"primaryKey;default:auto_random()" tag to use AUTO_RANDOM feature for TiDB.
TiDB supported SAVEPOINT from v6.2.0, please notice the version of TiDB when you use this feature.
TiDB supported FOREIGN KEY from v6.6.0, please notice the version of TiDB when you use this feature.

import (
  "fmt"
  "gorm.io/driver/mysql"
  "gorm.io/gorm"
)

type Product struct {
  ID    uint `gorm:"primaryKey;default:auto_random()"`
  Code  string
  Price uint
}

func main() {
  db, err := gorm.Open(mysql.Open("root:@tcp(127.0.0.1:4000)/test"), &gorm.Config{})
  if err != nil {
    panic("failed to connect database")
  }

  db.AutoMigrate(&Product{})

  insertProduct := &Product{Code: "D42", Price: 100}

  db.Create(insertProduct)
  fmt.Printf("insert ID: %d, Code: %s, Price: %d\n",
    insertProduct.ID, insertProduct.Code, insertProduct.Price)

  readProduct := &Product{}
  db.First(&readProduct, "code = ?", "D42") 

  fmt.Printf("read ID: %d, Code: %s, Price: %d\n",
    readProduct.ID, readProduct.Code, readProduct.Price)
}

Clickhouse

https://github.com/go-gorm/clickhouse

import (
  "gorm.io/driver/clickhouse"
  "gorm.io/gorm"
)

func main() {
  dsn := "tcp://localhost:9000?database=gorm&username=gorm&password=gorm&read_timeout=10&write_timeout=20"
  db, err := gorm.Open(clickhouse.Open(dsn), &gorm.Config{})

  
  db.AutoMigrate(&User{})
  
  db.Set("gorm:table_options", "ENGINE=Distributed(cluster, default, hits)").AutoMigrate(&User{})

  
  db.Create(&user)

  
  db.Find(&user, "id = ?", 10)

  
  var users = []User{user1, user2, user3}
  db.Create(&users)
  
}

Connection Pool

GORM using database/sql to maintain connection pool

sqlDB, err := db.DB()


sqlDB.SetMaxIdleConns(10)


sqlDB.SetMaxOpenConns(100)


sqlDB.SetConnMaxLifetime(time.Hour)

Refer Generic Interface for details

Unsupported Databases

Some databases may be compatible with the mysql or postgres dialect, in which case you could just use the dialect for those databases.

For others, you are encouraged to make a driver, pull request welcome!