# DATE\_TRUNC

将日期截断到给定时间单位。

## 语法

```
DATE_TRUNC(unit, time)
```

## 参数

| 名称 | 类型 | 描述 | 默认值 |
| --- | --- | --- | --- |
| 单位 | 字符串 |  |  |
| 时间 | 时间戳 |  |  |

## 返回

时间戳

***

## 示例

| 单位 | 时间 | 输出 |
| --- | --- | --- |
| "毫秒" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-02-03 04:05:06.789" |
| "秒" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-02-03 04:05:06" |
| "分钟" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-02-03 04:05:00" |
| "小时" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-02-03 04:00:00" |
| "日" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-02-03 00:00:00" |
| "周" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-02-01 00:00:00" |
| "月" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-02-01 00:00:00" |
| "季" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-01-01 00:00:00" |
| "年" | 时间戳 "2021-02-03 04:05:06.789" | 时间戳 "2021-01-01 00:00:00" |
| "毫秒" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-12-31 23:59:59.999" |
| "秒" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-12-31 23:59:59" |
| "分钟" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-12-31 23:59:00" |
| "小时" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-12-31 23:00:00" |
| "日" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-12-31 00:00:00" |
| "周" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-12-27 00:00:00" |
| "月" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-12-01 00:00:00" |
| "季" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-10-01 00:00:00" |
| "年" | 时间戳 "2021-12-31 23:59:59.999" | 时间戳 "2021-01-01 00:00:00" |
| "测试" | 时间戳 "2021-12-31 23:59:59.999" | null |