Mysql database learning

MySQL Database learning
The first is the installation of this package , Anyway, with gin The installation of the frame is a little similar , Because it won't be as troublesome as last time , As a result, it took a long time , But with the last experience , It's not enough to explode .
Understand with code ：

package main

import (
	"database/sql"
	"fmt"
	_ "github.com/go-sql-driver/mysql"
	"log"
)

func main() {
    
	connStr := "root:[email protected](127.0.0.1:3306)/ginsql"
	db, err := sql.Open("mysql", connStr)
	if err != nil {
    
		log.Fatal(err.Error())
		return
	}
	// Create database 
	_, err = db.Exec("create table person(" +
		"id int auto_increment primary key," +
		"name varchar(15) not null ," +
		"age int default 1" +
		");")
	// success err by nil
	if err != nil {
    
		log.Fatal(err.Error())
		return
	}
	// insert data 
	_, err = db.Exec("insert into person(name,age)"+"value(?,?);", "Alex", 15)
	_, err = db.Exec("insert into person(name,age)"+"value(?,?);", "David", 15)
	_, err = db.Exec("insert into person(name,age)"+"value(?,?);", "Tom", 17)
	_, err = db.Exec("insert into person(name,age)"+"value(?,?);", "jack", 18)
	if err != nil {
    
		log.Fatal(err.Error())
		return
	} else {
    
		fmt.Println(" Insert data succeeded ")
	}
	// Query data 
	row, err := db.Query("select id, name, age from person")
	if err != nil {
    
		log.Fatal(err.Error())
		return
	}
	for {
    
		if row.Next() {
    
			person := new(person)
			err := row.Scan(&person.Id, &person.Name, &person.Age)
			if err != nil {
    
				log.Fatal(err.Error())
				return
			}
			fmt.Println(person.Id, person.Name, person.Age)
		} else {
    
			break
		}
	}

}

type person struct {
    
	Id   int
	Name string
	Age  int
}

In fact, it is the code above the video
understand ：
Create database code ：

connStr := "root:[email protected](127.0.0.1:3306)/ginsql"
	db, err := sql.Open("mysql", connStr)
	if err != nil {
    
		log.Fatal(err.Error())
		return
	}
// Create database 
	_, err = db.Exec("create table person(" +
		"id int auto_increment primary key," +
		"name varchar(15) not null ," +
		"age int default 1" +
		");")
	// success err by nil
	if err != nil {
    
		log.Fatal(err.Error())
		return
	}

This part needs to be in MySQL Create relevant databases in the Library , front connStr := "root:[email protected](127.0.0.1:3306)/ginsql" In this part, we should pay attention to @tcp() It's fixed operation , At the same time, pay attention to 3306, I just wrote it wrong as 3360, Wasted time , Back ginsql For the relevant database . meanwhile , If you succeed in establishing , Next time, you can't create a library with the same name , Otherwise, it will report a mistake .
// insert data

	_, err = db.Exec("insert into person(name,age)"+"value(?,?);", "Alex", 15)
	_, err = db.Exec("insert into person(name,age)"+"value(?,?);", "David", 15)
	_, err = db.Exec("insert into person(name,age)"+"value(?,?);", "Tom", 17)
	_, err = db.Exec("insert into person(name,age)"+"value(?,?);", "jack", 18)

This part , I repeated it several times , It is found that the results are superimposed .
Query data ：

// Query data 
	row, err := db.Query("select id, name, age from person")
	if err != nil {
    
		log.Fatal(err.Error())
		return
	}
	for {
    
		if row.Next() {
    
			person := new(person)
			err := row.Scan(&person.Id, &person.Name, &person.Age)
			if err != nil {
    
				log.Fatal(err.Error())
				return
			}
			fmt.Println(person.Id, person.Name, person.Age)
		} else {
    
			break
		}
	}
}

Mainly row.Next() Code , It will run from the top of the table , If there is data behind it, it is true , If it is not false , At the end of each execution , Will point to the next line .
result ：