The orm framework for the golang common library operations database gorm basic use details

Common golang libraries: gorilla/ ES3en-ES4en routing libraries used
Common golang libraries: Configuration file parsing library - used by viper
golang Common libraries: orm framework for operating databases -gorm basic use

1: Field mapping - Model definition

struct is commonly used in gorm to map fields 模型定义

For example, we define a model Model:

type User struct {
	gorm.Model
	UserId int64 `gorm:"index"` // Set up the 1 A normal index with no index name set, gorm It will be named automatically 
	Birtheday time.Time
 Age  int  `gorm:"column:age"`//column:1 a tag , you can set the column name 
 Name string `gorm:"size:255;index:idx_name_add_id"`//size: Set the length size, index: Set the index, and that's it 1 An index name 
	Num  int  `gorm:"AUTO_INCREMENT"`
 Email string `gorm:"type:varchar(100);unique_index"`//type: Define the field type and size 
	AddressID sql.NullInt64 `gorm:"index:idx_name_add_id"`
	IgnoreMe int  `gorm:"_"`
	Description string `gorm:"size:2019;comment:' User description field '"`//comment : Field comment 
	Status string `gorm:"type:enum('published', 'pending', 'deleted');default:'pending'"`
}

gorm. Model above is defined as follows:

type Model struct {
 ID uint `gorm:"primary_key"`//primary_key: Set the primary key 
 CreatedAt time.Time
 UpdatedAt time.Time
 DeletedAt *time.Time
}

Of course, we can also define a similar type without ES31en.Model

If you use ID, the system will automatically set the table as the primary key. Of course, we can define our own primary key:
Such as:

//  use `AnimalID` A primary key 
type Animal struct {
 AnimalID int64 `gorm:"primary_key"`
 Name string
 Age int64
}

Reference: https: / / gorm io zh_CN/docs/conventions html

2: Create the table

Look directly at the following example: ES52en.go

package main

import (
	"database/sql"
	"fmt"
	"github.com/jinzhu/gorm"
	_ "github.com/jinzhu/gorm/dialects/mysql"
	"time"
)

type User struct {
	gorm.Model
	UserId int64 `gorm:"index"`
	Birtheday time.Time
	Age  int  `gorm:"column:age"`
	Name string `gorm:"size:255;index:idx_name_add_id"`
	Num  int  `gorm:"AUTO_INCREMENT"`
	Email string `gorm:"type:varchar(100);unique_index"`
	AddressID sql.NullInt64 `gorm:"index:idx_name_add_id"`
	IgnoreMe int  `gorm:"_"`
	Description string `gorm:"size:2019;comment:' User description field '"`
	Status string `gorm:"type:enum('published', 'pending', 'deleted');default:'pending'"`
}

// Sets the table name, which defaults to the plural form of the structure's name 
func (User) TableName() string {
	return "VIP_USER"
}

func main() {
	db, err := gorm.Open("mysql", "root:root@/gormdemo?charset=utf8&parseTime=True&loc=Local")
	if err != nil {
		fmt.Println("connect db err: ", err)
	}
	defer db.Close()

	if db.HasTable(&User{}) { // Determine if the table exists 
		db.AutoMigrate(&User{}) // There is an automatic adaptation table, which means that if there are no fields previously, the fields will be added 
	} else {
		db.CreateTable(&User{}) // Create a new table if it does not exist 
	}
}

The gorm.Open () operation above needs parentheses if you want to specify the host ()
Such as:

user:password@(localhost)/dbname?charset=utf8&parseTime=True&loc=Local

In the above program, we first created a new database named gormdemo And then run: go run createtable.go , the database will appear with the name of one vip_user In the table.

3: Add, delete, change and check

Create a new database for gormdemo and then execute the sql statement below to create a table for animals with 1 more test data

CREATE TABLE `animals` (
 `id` bigint(20) NOT NULL AUTO_INCREMENT,
 `name` varchar(255) DEFAULT 'galeone',
 `age` int(10) unsigned DEFAULT '0',
 PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=8 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of animals
-- ----------------------------
INSERT INTO `animals` VALUES ('1', 'demo-test', '20');
INSERT INTO `animals` VALUES ('2', 'galeone', '30');
INSERT INTO `animals` VALUES ('3', 'demotest', '30');
INSERT INTO `animals` VALUES ('4', 'jim', '90');
INSERT INTO `animals` VALUES ('5', 'jimmy', '10');
INSERT INTO `animals` VALUES ('6', 'jim', '23');
INSERT INTO `animals` VALUES ('7', 'test3', '27');

increase

Example: create go

package main

import (
	"fmt"

	"github.com/jinzhu/gorm"
	_ "github.com/jinzhu/gorm/dialects/mysql"
)

type Animal struct {
	ID int64
	Name string
	Age int64
}

func main() {
	db, err := gorm.Open("mysql", "root:root@/gormdemo?charset=utf8&parseTime=true&loc=Local")
	if err != nil {
		fmt.Println("connect db error: ", err)
	}
	defer db.Close()

	animal := Animal{Name: "demo-test", Age: 20}
	db.Create(&animal)
}

Note: In the above example, I create a data table of animals in mysql with fields id, name, age

To find the

select.go

package main

import (
	"fmt"

	"github.com/jinzhu/gorm"

	_ "github.com/jinzhu/gorm/dialects/mysql"
)

type Animal struct {
	ID int64
	Name string
	Age int64
}

//https://gorm.io/zh_CN/docs/query.html
func main() {
	db, err := gorm.Open("mysql", "root:root@/gormdemo?charset=utf8&parseTime=true&loc=Local")
	if err != nil {
		fmt.Println("connect db error: ", err)
	}
	defer db.Close()

	// According to the progressive query rule 1 records 
	var animal Animal
	db.First(&animal)
	fmt.Println(animal)

	// According to gradually query the last 1 records 
	var animal2 Animal
	db.Last(&animal2)
	fmt.Println(animal2)

	// Specifies a record (available only if the primary key is an integer) 
	var animal3 Animal
	db.First(&animal3, 2)
	fmt.Println(animal3)

	//where conditions 

	// The eligible number 1 records 
	var animal4 Animal
	db.Where("name = ?", "demotest2").First(&animal4)
	fmt.Println("where : ", animal4, animal4.ID, animal4.Name, animal4.Age)

	// All records that meet the criteria 
	var animals5 []Animal
	db.Where("name = ?", "galeone").Find(&animals5)
	fmt.Println(animals5)
	for k, v := range animals5 {
		fmt.Println("k:", k, "ID:", v.ID, "Name:", v.Name, "Age:", v.Age)
	}

	//IN
	var animals6 []Animal
	db.Where("name IN (?)", []string{"demo-test", "demotest2"}).Find(&animals6)
	fmt.Println(animals6)

	//LIKE
	var animals7 []Animal
	db.Where("name like ?", "%jim%").Find(&animals7)
	fmt.Println(animals7)

	//AND
	var animals8 []Animal
	db.Where("name = ? AND age >= ?", "jim", "24").Find(&animals8)
	fmt.Println(animals8)

	// The total number of 
	var count int
	var animals9 []Animal
	db.Where("name = ?", "galeone").Or("name = ?", "jim").Find(&animals9).Count(&count)
	fmt.Println(animals9)
	fmt.Println(count)

	//Scan,  Native queries 
	var animals10 []Animal
	db.Raw("SELECT id, name, age From Animals WHERE name = ? AND age = ? ", "galeone", "30").Scan(&animals10)
	fmt.Println("Scan: ", animals10)

	// Native queries, select all
	var animals11 []Animal
	rows, _ := db.Raw("SELECT id,name FROM Animals").Rows()
	// Note: Above  select id,name  I can't write  *  Replace, otherwise the results are the default 0 value 
	// And it goes like this:  ALL: [{0 0} {0 0} {0 0} {0 0} {0 0} {0 0} {0 0}]
	//Scan  What field is next, select  What field will follow 
	for rows.Next() {
		var result Animal
		rows.Scan(&result.ID, &result.Name)
		animals11 = append(animals11, result)
	}
	fmt.Println("ALL: ", animals11)
	//output:ALL: [{1 demo-test 0} {2 galeone 0} {3 demotest2 0} {4 galeone 0} {5 galeone 0} {6 jim 0} {7 jimmy 0}]

	//select  The query 
	var animal12 Animal
	db.Select("name,age").Find(&animal12) // Only the query name . age Field, equivalent to select name,age from user
	fmt.Println("select: ", animal12)
	// db.Select([]string{"name", "age"}).Find(&animal12)
	// fmt.Println("select2: ", animal12)
}

update

update.go

package main

import (
	"fmt"

	"github.com/jinzhu/gorm"
	_ "github.com/jinzhu/gorm/dialects/mysql"
)

type Animal struct {
	ID int64
	Name string
	Age int64
}

func main() {
	db, err := gorm.Open("mysql", "root:root@/gormdemo?charset=utf8&parseTime=true&loc=Local")
	if err != nil {
		fmt.Println("connect db error: ", err)
	}
	defer db.Close()

	/// According to the 1 Conditional update 
	// Update field values based on conditions ,
	// After it Debug() , run time, can print out sql
	db.Debug().Model(&Animal{}).Where("id = ? ", 4).Update("name", "jimupdate")
	//UPDATE `animals` SET `name` = 'jimupdate' WHERE (id = 4)

	// In addition 1 Kind of writing:   Update by condition 
	var animal Animal
	animal = Animal{ID: 3}
	db.Debug().Model(animal).Update("name", "demotest2update")
	// db.Debug().Model(&animal).Update("name", "demotest2update") //  I could write it this way 
	//UPDATE `animals` SET `name` = 'demotest2update' WHERE `animals`.`id` = 3

	///  Multiple conditional updates 
	db.Model(&Animal{}).Where("id = ? AND age = ?", 4, 45).Update("name", "jimupdate3")
	//UPDATE `animals` SET `name` = 'jimupdate2' WHERE (id = 4 AND age = 45)

	///  Updating multiple values 
	db.Debug().Model(&Animal{}).Where("id = ?", 4).Update(Animal{Name: "jim", Age: 90})
	// UPDATE `animals` SET `age` = 90, `name` = 'jim' WHERE (id = 4)

	animal2 := Animal{ID: 5}
	db.Debug().Model(&animal2).Update(map[string]interface{}{"name": "jimm", "age": 100})
	//UPDATE `animals` SET `age` = 100, `name` = 'jimm' WHERE `animals`.`id` = 5
}

delete

delete.go

package main

import (
	"fmt"

	"github.com/jinzhu/gorm"
	_ "github.com/jinzhu/gorm/dialects/mysql"
)

type Animal struct {
	ID int64
	Name string
	Age int64
}

func main() {
	db, err := gorm.Open("mysql", "root:root@/gormdemo?charset=utf8&parseTime=true&loc=Local")
	if err != nil {
		fmt.Println("connect db error: ", err)
	}
	defer db.Close()

	db.Debug().Where("id = ?", 13).Delete(&Animal{})
	// DELETE FROM `animals` WHERE (id = 13)

	db.Debug().Delete(&Animal{}, "id = ? AND age = ?", 14, 10)
	//DELETE FROM `animals` WHERE (id = 14 AND age = 10)

}

4: Debug

Add Debug() directly after db, as in delete.go

5: reference

https://gorm.io/zh_CN/