由Sqlite在一段时间内选择数据

Question

我想在一段时间内计算/选择数据字段。使用以下格式时，我明确指定整个时间戳，查询是正确的。

SELECT TimeStamp,strftime('%Y',TimeStamp) as "Year",
strftime('%m',TimeStamp) as "Month",
strftime('%d',TimeStamp) as "Day",
strftime('%M',TimeStamp) as "Minute",
strftime('%H', TimeStamp) as "Hours"
FROM temp
WHERE TimeStamp between '2017-12-22T20:50:00' and '2017-12-23T21:00:00'

我尝试做的是在一定时间内选择带有时间戳的字段。所以我将我的查询修改为：

SELECT TimeStamp,strftime('%Y',TimeStamp) as "Year",
strftime('%m',TimeStamp) as "Month",
strftime('%d',TimeStamp) as "Day",
strftime('%M',TimeStamp) as "Minute",
strftime('%H', TimeStamp) as "Hours"
FROM temp
WHERE strftime('%H', TimeStamp) between 20 and 21

然后查询返回0行，我在哪里做错了？我的时间戳格式遵循sqlite约定为YYYY-mm-dd HH：MM：SS.3u。以下是我的时间戳示例：2017-12-22T20：57：02.188Z

Answer 1

SELECT TimeStamp,strftime('%Y',TimeStamp) as "Year",
strftime('%m',TimeStamp) as "Month",
strftime('%d',TimeStamp) as "Day",
strftime('%M',TimeStamp) as "Minute",
strftime('%H', TimeStamp) as "Hours"
FROM temp
WHERE cast(strftime('%H', TimeStamp) as int) between 20 and 21

strftime返回一个字符串，与int进行比较。将字符串转换为int来解决这个问题

Answer 2

你的指令strftime('%H', TimeStamp)被认为是一个字符串。因此无法与整数进行比较。您需要将其显式地转换为int。

CAST(strftime('%H', TimeStamp) AS INT)