query database in golang into a map/hash table instead of struct

queryMap.go

import (
	"database/sql"
	_ "github.com/lib/pq"
	"log"
)

// queryMap is used for quickly running a SQL query that returns only one
// row. Important: This shouldn't ever return errors and shouldn't ever
// be applied on user input. Ideally, you're querying non-nullable
// columns using keys you got from some trusted (non-human)
// source. Slow(er)? Yes. But this is good for prototyping and relieving
// Go-related RSI. Works on Postgres + lib/pq + database/sql.
// Usage:
// a := queryMap(dbPtr, "select first_name from customers where balance >= $1", 1000)
// for _, firstName := range a {
// 	fmt.Println(a["first_name"].(string)) // you must know what type the db driver converts your columns to
// }
func queryMap(db *sql.DB, sql string, cols ...interface{}) []map[string]interface{} {
	rows, err := db.Query(sql, cols...)
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()
	ret := make([]map[string]interface{}, 0)
	for rows.Next() {
		colVals := make([]interface{}, len(cols))
		for i := range colVals {
			colVals[i] = new(interface{})
		}
		err = rows.Scan(colVals...)
		if err != nil {
			log.Fatal(err)
		}
		colNames, err := rows.Columns()
		if err != nil {
			log.Fatal(err)
		}
		these := make(map[string]interface{})
		for idx, name := range colNames {
			these[name] = *colVals[idx].(*interface{})
		}
		ret = append(ret, these)
	}
	if err = rows.Err(); err != nil {
		log.Fatal(err)
	}
	return ret
}

// queryMapOne is queryMap just for one row only.
func queryMapOne(db *sql.DB, sql string, cols ...interface{}) map[string]interface{} {
	xs := queryMap(db, sql, cols...)
	if len(xs) == 0 {
		log.Fatalf("Empty result set")
		return nil
	} else {
		return xs[0]
	}
}