golang flag的使用

package main

import (
	"backend-service-api-scripts/utils"
	"database/sql"
	"flag"
	"fmt"
	"log"
	"os"
)

var (
	db         *sql.DB = utils.ConnectData() // 这里的连接数据库需要根据数据库本身的情况进行更改
	courseId   int
	companyId  int
	outputFile string
	inputFile  string
	h          bool
)

func init() {
	flag.BoolVar(&h, "h", false, "帮助")
	flag.IntVar(&courseId, "c", 0, "(必传值)课程ID:\n\tA课：111\n\tB课：222\n\tC课：333")
	flag.IntVar(&companyId, "C", 0, "(必传值)企业ID")
	flag.StringVar(&inputFile, "i", "inputFile.txt", "需要查询的电话列表文件")
	flag.StringVar(&outputFile, "o", "outputFile.txt", "查询电话对应的班级号文件")

	flag.Usage = usage
}

func usage() {
	fmt.Fprintf(os.Stderr, `View class number by phone
Usage: viewClassNumber [-c courseId] [-C companyId] [-i inputFile] [-o outputFile]
Options:
`)
	flag.PrintDefaults()
}

type UserClassesInfo struct {
	ClasseNo sql.NullString
}

func getUserGroupId(phoneList <-chan string, courseId, companyId int) {
	for {
		phone, ok := <-phoneList
		if !ok {
			break
		}
		row := db.QueryRow("SELECT classes_no FROM classes.classes_info WHERE phone=? AND course_id=? AND company_id=?", phone, courseId, companyId)
		u := UserClassesInfo{}
		if err := row.Scan(&u.ClasseNo); err != nil {
			log.Println(err)
		}
		info := fmt.Sprintf("%v\t%v\n", phone, u.ClasseNo.String)
		utils.WriteFile(outputFile, &info)
	}
}

func main() {
	flag.Parse()
	if h || companyId == 0 || courseId == 0 {
		flag.Usage()
		return
	}
	phoneList := make(chan string, 500)
	utils.ReadFile(inputFile, phoneList)
	getUserGroupId(phoneList, courseId, companyId)
}