错误：标准软件包中非标准导入“ github.com/go-sql-driver/mysql”

I want to retrieve some data from my database using go language. This is very beginning my code in file main.go

package main

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

... *(the rest code)*

But, I got error:

C:\Go\src\iwantto\main.go:6:2: non-standard import "github.com/go-sql-driver/mysql" in standard package "iwantto"

I already doing some research in google and forum, but there nothing much about that import. Or, is it really a bug from go language itself?