[Yandex Cloud documentation](../../index.md) > [Yandex DataLens](../index.md) > Calculated fields > Function reference > Date/Time functions > WEEK

# WEEK



#### Syntax {#syntax}


```
WEEK( value )
```

#### Description {#description}
The number of the week according to [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601). The first week is the week that contains the first Thursday of the year or January 4th.

**Argument types:**
- `value` — `Date | Datetime`


**Return type**: `Integer`

#### Example {#examples}

```
WEEK(#1971-01-14 01:02:03#) = 2
```


#### Data source support {#data-source-support}

`ClickHouse 21.8`, `Files`, `Google Sheets`, `Microsoft SQL Server 2017 (14.0)`, `MySQL 5.7`, `Oracle Database 12c (12.1)`, `PostgreSQL 9.3`, `Trino`, `Yandex Documents`, `YDB`.