A lot of data to postgres database with golang

gistfile0.go

package main

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"

	_ "github.com/lib/pq"
)

const (
	host     = "localhost"
	port     = 5432
	user     = "postgres"
	password = "postgres"
	dbname   = "teste"
)

type File struct {
	CouponCode string `json:"coupon_code"`
}

func main() {
	psqlInfo := fmt.Sprintf("host=%s port=%d user=%s "+
		"password=%s dbname=%s sslmode=disable",
		host, port, user, password, dbname)

	db, err := sql.Open("postgres", psqlInfo)
	if err != nil {
		panic(err)
	}
	defer db.Close()

	file, err := os.Open("data.json")

	if err != nil {
		panic(err)
	}

	defer file.Close()

	byteValue, _ := ioutil.ReadAll(file)

	var fileData []File

	json.Unmarshal(byteValue, &fileData)

	sqlStr := "INSERT INTO partner_validation_code(code, partner_id, active) VALUES "

	for _, row := range fileData {
		sqlStr += fmt.Sprintf("('%s', 5, %t),", row.CouponCode, true)
	}

	//trim the last ,
	sqlStr = sqlStr[0 : len(sqlStr)-1]

	fmt.Println(sqlStr)

	// prepare the statement
	db.Exec(sqlStr)
}