Port duplication error using socket programming in Golang

Question

Using this type of function, whatever port I use, it gives error of duplicate port. Is there any way to know which port to be used specifically for connection with PG.

package main
import (
        "fmt"
        "net"
)
const (
        SERVER_HOST = "localhost"
        SERVER_PORT = "1234"
        SERVER_TYPE = "tcp"
)

I tried using multiple ports. One time I gave the same port number as in PG server, it got run that time but later on same issue