---
{
    "title": "week",
    "language": "zh-CN"
}
---

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# week
## description
### Syntax

`INT YEARWEEK(DATE date)`
`INT YEARWEEK(DATE date, INT mode)`

返回指定日期的星期数。mode的值默认为0。
参数mode的作用参见下面的表格：
|Mode |星期的第一天 |星期数的范围 |第一个星期的定义                            |
|:---|:-------------|:-----------|:--------------------------------------------|
|0   |星期日        |0-53        |这一年中的第一个星期日所在的星期             |
|1   |星期一        |0-53        |这一年的日期所占的天数大于等于4天的第一个星期|
|2   |星期日        |1-53        |这一年中的第一个星期日所在的星期             |
|3   |星期一        |1-53        |这一年的日期所占的天数大于等于4天的第一个星期|
|4   |星期日        |0-53        |这一年的日期所占的天数大于等于4天的第一个星期|
|5   |星期一        |0-53        |这一年中的第一个星期一所在的星期             |
|6   |星期日        |1-53        |这一年的日期所占的天数大于等于4天的第一个星期|
|7   |星期一        |1-53        |这一年中的第一个星期一所在的星期             |

参数为Date或者Datetime类型

## example
```
mysql> select yearweek('2021-1-1');
+----------------------+
| yearweek('2021-1-1') |
+----------------------+
|               202052 |
+----------------------+
```
```
mysql> select yearweek('2020-7-1');
+----------------------+
| yearweek('2020-7-1') |
+----------------------+
|               202026 |
+----------------------+
```
```
mysql> select yearweek('2024-12-30',1);
+------------------------------------+
| yearweek('2024-12-30 00:00:00', 1) |
+------------------------------------+
|                             202501 |
+------------------------------------+
```

## keyword
    WEEK