// Very simple example of getting data from postgres DB in GO
// Prior to running this program you have to set things up so that
// go knows how to use/do the github import
// Two commands: at the command line in the directory in which this
// code sits:
//      go mod init que.go
//      go get github.com/lib/pq

package main

import (
	"database/sql"
	"fmt"

	_ "github.com/lib/pq" // _ means that this import is referred to as pq
)

// the information needed to connect to the DB server.
// Note localhost!!!!
const (
    host     = "localhost"
    port     = 5432
    user     = "dbuser"
    password = "12345678"
    dbname   = "sakila"
)
 
func main() {
    // connection string
    psqlconn := fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s sslmode=disable", host, port, user, password, dbname)
         
    // open database
    db, err := sql.Open("postgres", psqlconn)
    CheckError(err)
     
    // close database
    defer db.Close()
 
    // check db
    err = db.Ping()
    CheckError(err)
 
    fmt.Println("Connected!")
	getData(db)
}

// actually do a query
func getData(db *sql.DB) {
	rows, err := db.Query("select first_name, last_name from actor where last_name like 'A%'")
	CheckError(err)
 
	defer rows.Close()
	for rows.Next() {
    	var fn string
		var ln string

    	err = rows.Scan(&fn, &ln)
    	CheckError(err)
 
    	fmt.Printf("First:%s last:%s\n", fn, ln);
	}
 
}

// very basic, and aggressive error handler.
func CheckError(err error) {
    if err != nil {
        panic(err)
    }
}