About go using mysql testing

package main

import (
    "github.com/jmoiron/sqlx"
    _ "github.com/go-sql-driver/mysql"
    "fmt"
)

func main() {
    Db,err:=sqlx.Open("mysql","root:123456@tcp(127.0.0.1:3306)/ghnv2_test")
    if err != nil{
        fmt.Println("connect to mysql failed,",err)
        return
    }
    defer Db.Close()
    fmt.Println("connect to mysql success")

    //执行sql语句，切记这里的占位符是？
    result,err := Db.Exec("INSERT INTO sysuser_tag(tag_name,shop_id,user_id)VALUES (?,?,?)","运动",12,24)
    if err != nil{
        fmt.Println("insert failed,",err)
    }
    // 通过LastInsertId可以获取插入数据的id
    tagId,err:= result.LastInsertId()
    // 通过RowsAffected可以获取受影响的行数
    rowCount,err:=result.RowsAffected()
    fmt.Println("tag_id:",tagId)
    fmt.Println("rowCount:",rowCount)
}

package main

import (
    "github.com/jmoiron/sqlx"
    _ "github.com/go-sql-driver/mysql"
    "fmt"
)

func main() {
   
    Db,err:=sqlx.Open("mysql","root:123456@tcp(127.0.0.1:3306)/ghnv2_test")
    if err != nil{
        fmt.Println("connect to mysql failed,",err)
        return
    }
    defer Db.Close()
    fmt.Println("connect to mysql success")

    //执行查询操作
    rows,err := Db.Query("SELECT tag_name FROM sysuser_tag WHERE tag_id>=7")
    if err != nil{
        fmt.Println("select db failed,err:",err)
        return
    }
    // 这里获取的rows是从数据库查的满足tag_id>=5的所有行的tag_name信息，rows.Next(),用于循环获取所有
    for rows.Next(){
        var s string
        err = rows.Scan(&s)
        if err != nil{
            fmt.Println(err)
            return
        }
        fmt.Println(s)
    }
    rows.Close()

}