# Date time functions
<a name="sql-functions-date"></a>

 Date time functions work with dates and times. These functions allow extraction of specific components of a date, perform calculations, and manipulate date values.

The allowed identifiers in these functions are:
+ YEAR
+ MONTH
+ DAY
+ HOUR
+ MINUTE
+ SECOND


|  **Function**  |  **Signature**  |  **Description**  | 
| --- | --- | --- | 
| `NOW` |  NOW ( )  | Returns the current timestamp with millisecond precision. It provides the exact time at the moment it's executed within a query. | 
| `DATE_ADD` | DATE\_ADD (identifier, interval\_duration, column) | Returns the sum of a date/time and a number of days/hours, or of a date/time and date/time interval. | 
| `DATE_SUB` | DATE\_SUB (identifier, interval\_duration, column) | Returns the difference between a date/time and a number of days/hours, or between a date/time and date/time interval. | 
| `TIMESTAMP_ADD` | TIMESTAMP\_ADD (identifier, interval\_duration, column) | Adds an interval of time, in the given time units, to a datetime expression. | 
| `TIMESTAMP_SUB` | TIMESTAMP\_SUB (identifier, interval\_duration, column) | Subtracts an interval of time, in the given time units, from a datetime expression. | 
| `CAST` | CAST (expression AS TIMESTAMP FORMAT pattern) | Converts a string expression to a timestamp using the specified format pattern. Common patterns include `'yyyy-MM-dd HH:mm:ss'` for standard datetime format. For example, `SELECT CAST('2023-12-25 14:30:00' AS TIMESTAMP) AS converted_timestamp` | 

**Example of a SQL query using the listed functions:**  

```
SELECT r.asset_id, r.int_value,
  date_add(DAY, 7, r.event_timestamp) AS date_in_future,
  date_sub(YEAR, 2, r.event_timestamp) AS date_in_past,
  timestamp_add(DAY, 2, r.event_timestamp) AS timestamp_in_future,
  timestamp_sub(DAY, 2, r.event_timestamp) AS timestamp_in_past,
  now() AS time_now
FROM raw_time_series AS r
```