我如何获得一天前相对于当前时间的时间？

I need to query my db for events occurred within a single hour. Therefore, I want to get events between now and then (which is now - 24 hours, or now - 1 full day).

I tried this approach, but it is incorrect -

package main

import (
    "fmt"
    "time"
)

func main() {

    now := time.Now()

    // print the time now
    fmt.Println(now)

    then := time.Now()
    diff := 24
    diff = diff.Hours()
    then = then.Add(-diff)

    // print the time before 24 hours
    fmt.Println(then)

    // print the delta between 'now' and 'then'
    fmt.Println(now.Sub(then))
}

How can I make then == 1 full day / 24 hours before now ?

Thanks a lot for your help!!

Use the Duration constants provided in the time package, like time.Hour

diff := 24 * time.Hour
then := time.Now().Add(-diff)

Or if you want the same time on the previous day (which may not be 24 hours earlier, http://play.golang.org/p/B32RbtUuuS)

then := time.Now().AddDate(0, 0, -1)