DATE_SUB()怎么使用
时间: 2023-05-18 12:05:30 浏览: 57
DATE_SUB()函数用于从日期中减去一定的时间间隔。它的语法如下:
```
DATE_SUB(date, INTERVAL expr unit)
```
其中,date是要减去时间间隔的日期,expr是时间间隔的数量,unit是时间间隔的单位。unit可以是以下值之一:
- MICROSECOND
- SECOND
- MINUTE
- HOUR
- DAY
- WEEK
- MONTH
- QUARTER
- YEAR
下面是一些使用DATE_SUB()函数的示例:
1. 从当前日期中减去1天:
```
SELECT DATE_SUB(NOW(), INTERVAL 1 DAY);
```
2. 从指定日期中减去2个月:
```
SELECT DATE_SUB('2021-01-01', INTERVAL 2 MONTH);
```
3. 从指定日期中减去3周:
```
SELECT DATE_SUB('2021-01-01', INTERVAL 3 WEEK);
```
4. 从指定日期中减去4小时:
```
SELECT DATE_SUB('2021-01-01 12:00:00', INTERVAL 4 HOUR);
```
注意:DATE_SUB()函数返回的是一个日期类型的值,可以直接用于比较或者作为其他函数的参数。
相关问题
DATE_SUB的使用
DATE_SUB() 是一个 SQL 函数,用于从当前日期中减去指定的时间间隔。其语法如下:DATE_SUB(date, INTERVAL unit value)。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
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hql date_sub
HQL (Hive Query Language) provides the `date_sub` function, which is used to subtract a specified number of days from a given date.
The syntax for the `date_sub` function in HQL is as follows:
```
date_sub(date, num_days)
```
Here, `date` is the input date from which you want to subtract days, and `num_days` is the number of days you want to subtract.
For example, to subtract 7 days from the current date, you can use the following query:
```
SELECT date_sub(current_date(), 7);
```
This will return a date that is 7 days before the current date.
Note that the `date_sub` function only works with dates and not with timestamps. If you need to subtract days from a timestamp, you can extract the date part using the `date` function and then use `date_sub`.