Convert Select query obtained from Postgre with Go to JSON

Thing you want to do

--I want to convert the entire query obtained by the SELECT statement to JSON --It seems that the scan of the sql package is processing line by line, so you need to create an array in the loop (?) --Convert from array with json package --The reference code is on the MS site



package main

import (
    _ ""

const (
    // Initialize connection constants.
    HOST     = ""
    DATABASE = "testdb"
    USER     = "root"
    PASSWORD = "password"

func checkError(err error) {
    if err != nil {

func main() {

    // Initialize connection string.
    var connectionString string = fmt.Sprintf("host=%s user=%s password=%s dbname=%s sslmode=disable", HOST, USER, PASSWORD, DATABASE)

    // Initialize connection object.
    db, err := sql.Open("postgres", connectionString)

    err = db.Ping()
    fmt.Println("Successfully created connection to database")

    // Read rows from table.
    var id int
    var name string
    var quantity int

    sql_statement := "SELECT * from inventory;"
    rows, err := db.Query(sql_statement)
    defer rows.Close()

    //Define structure
    type data struct {
        ID int
        Name string
        Quantity int

    //Declare array type
    var fruit []data

    for rows.Next() {
        switch err := rows.Scan(&id, &name, &quantity); err {
        case sql.ErrNoRows:
            fmt.Println("No rows were returned")
        case nil:
            fmt.Printf("Data row = (%d, %s, %d)\n", id, name, quantity)

            //Add array line by line
            fruit = append(fruit,data{
                ID: id,
                Name: name,
                Quantity: quantity,

    fruitjson, _ := json.Marshal(fruit)



yuta:~/postgre $ go run main.go 
Successfully created connection to database
Data row = (1, banana, 150)
Data row = (2, orange, 154)
Data row = (3, apple, 100)
Data row = (4, test, 100)


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