How to use GORM to operate database in Golang

Golang is a fast and efficient programming language that is widely used in fields such as web applications, mobile applications, and IoT devices. In Golang programming, using GORM can easily operate the database, making development more efficient and simple. This article will introduce how to use GORM to operate databases in Golang.

GORM is a Golang-based ORM library that can map structured data to a relational database. It supports MySQL, PostgreSQL, SQLite, SQL Server and other databases, provides a flexible query API, and can easily perform CRUD operations.

GORM installation

Before using GORM, you need to install it first. You can use Golang's package management tool go get to install GORM:

go get -u github.com/jinzhu/gorm

Using GORM

Using GORM mainly includes the following steps:

1. Connect to the database

Before using GORM, you need to connect to the database first. You can connect to the database through the Open method:

import "github.com/jinzhu/gorm"

db, err := gorm.Open("mysql", "user:password@tcp(127.0.0.1:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local")
if err != nil {
    panic(err)
}
defer db.Close()

Here is MySQL as an example, where "mysql" represents the database engine, "user" and "password" represent the database user name and password, and "127.0.0.1:3306" represents the database Address and port, "dbname" represents the name of the database to be connected, "charset=utf8mb4&parseTime=True&loc=Local" represents the connection parameters.

2. Define the data model

Before using GORM for database operations, you need to define the data model. GORM uses a structure to represent the data model, and the fields of the structure correspond to the table fields in the database. For example, define a User structure to represent a user:

type User struct {
    ID        uint   `gorm:"primary_key"`
    Name      string
    Age       int
    Gender    string
    Email     string
}

Five fields are defined here, corresponding to ID, name, age, gender and email in the database.

3. Create table

After defining the data model, you need to create the database table through GORM. You can use the AutoMigrate method to create a table:

db.AutoMigrate(&User{})

The parameter passed here is a pointer of User type, indicating that a User table is to be created.

4. Inserting data

It is very convenient to use GORM to insert data. You only need to create a User instance and call the Create method:

user := User{Name: "John", Age: 25, Gender: "Male", Email: "john@example.com"}
db.Create(&user)

Created here A user named John and insert it into the database.

5. Query data

GORM’s query API is very flexible and supports multiple query methods. The following are some commonly used query APIs:

Query all users:

var users []User
db.Find(&users)

Query users based on ID:

var user User
db.First(&user, 1) // 查询id为1的用户

Query users based on conditions:

var users []User
db.Where("age > ?", 20).Find(&users) // 查询年龄大于20岁的用户

6. Update data

Updating data is also very simple. You can use the Model method to locate the record to be updated, and update it through the Update method:

db.Model(&user).Update("email", "john@example.com")

The user’s email field is updated here. "john@example.com".

7. Delete data

To delete data, you can use the Delete method:

db.Delete(&user)

The user record is deleted here.

Summary

GORM is a very convenient and flexible ORM library that can greatly simplify the work of operating databases in Golang. This article introduces the installation, usage process and common APIs of GORM, hoping to be helpful to Golang developers.

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