go lang crawler concurrency and sync example

goCraw2.go

package main

import (
	"database/sql"
	"fmt"
	"io/ioutil"
	"net/http"
	"strconv"
	"sync"
	"time"

	_ "github.com/go-sql-driver/mysql"
)

//NewWriteSQLVersion ddd
func NewWriteSQLVersion(catPages string, cat_id int) {
	db, err := sql.Open("mysql", "root:@/crawler?charset=utf8")
	checkErr(err)

	// insert
	stmt, err := db.Prepare("INSERT i_rehber SET kategori_sayfalari=?,kategori_id=?,add_date=?")
	checkErr(err)

	res, err := stmt.Exec(catPages, cat_id, time.Now())
	checkErr(err)
	fmt.Print(res)
}

func checkErr(err error) {
	if err != nil {
		panic(err)
	}
}
func main() {
	var kategoriID = 6
	var kac_sayfa = 4
	var urladres = "http://www.example.com?_"
	var urls [4]string
	for i := 0; i < kac_sayfa; i++ {
		new := i * 20
		t := strconv.Itoa(new)
		urls[i] = urladres + t + ".html"
	}
	fmt.Print(urls)

	var wg sync.WaitGroup
	wg.Add(len(urls))
	for _, url := range urls {
		go func(url string) {
			defer wg.Done()
			response, err := http.Get(url)
			if err != nil {
				// error handling
			}
			//  fmt.Printf("%s: %s\n",url,response.Status)
			defer response.Body.Close()
			body, err := ioutil.ReadAll(response.Body)

			NewWriteSQLVersion(string(body), kategoriID)

			fmt.Print(string(body))
		}(url)
	}
	wg.Wait() // waits until the url checks complete
	fmt.Print(urls)

}