# MySQL EXTRACT() 函数

## 定义和用法

EXTRACT() 函数用于返回日期/时间的单独部分，比如年、月、日、小时、分钟等等。

### 语法

     EXTRACT(unit FROM date)

date 参数是合法的日期表达式。unit 参数可以是下列的值：

Unit 值
MICROSECOND
SECOND
MINUTE
HOUR
DAY
WEEK
MONTH
QUARTER
YEAR
SECOND_MICROSECOND
MINUTE_MICROSECOND
MINUTE_SECOND
HOUR_MICROSECOND
HOUR_SECOND
HOUR_MINUTE
DAY_MICROSECOND
DAY_SECOND
DAY_MINUTE
DAY_HOUR
YEAR_MONTH

### 实例

假设我们有如下的 "Orders" 表：

OrderId | ProductName | OrderDate
--- | --- | ---
1 | Jarlsberg Cheese | 2008-11-11 13:23:44.657

下面是 SELECT 语句：

     SELECT EXTRACT(YEAR FROM OrderDate) AS OrderYear,
     EXTRACT(MONTH FROM OrderDate) AS OrderMonth,
     EXTRACT(DAY FROM OrderDate) AS OrderDay,
     FROM Orders
     WHERE OrderId=1

结果如下所示：

OrderYear | OrderMonth | OrderDay
--- | --- | ---
2008 | 11 | 11