在本教程中，您将学习如何使用MySQL EXTRACT()函数来提取DATE或DATETIME值的一部分。
简介MySQL EXTRACT函数
EXTRACT()函数提取日期的一部分。下面说明了EXTRACT()函数的语法。
EXTRACT(unit FROM date)
EXTRACT()函数需要两个参数：unit和date。
unit是要从日期中提取的间隔。 以下是unit参数的有效间隔。
- DAY
- DAY_HOUR
- DAY_MICROSECOND
- DAY_MINUTE
- DAY_SECOND
- HOUR
- HOUR_MICROSECOND
- HOUR_MINUTE
- HOUR_SECOND
- MICROSECOND
- MINUTE
- MINUTE_MICROSECOND
- MINUTE_SECOND
- MONTH
- QUARTER
- SECOND
- SECOND_MICROSECOND
- WEEK
- YEAR
- YEAR_MONTH
date是DATE或DATETIME值，从中提取间隔的日期。
MySQL EXTRACT函数示例
从日期时间提取日期：
mysql> SELECT EXTRACT(DAY FROM '2017-07-14 09:04:44') DAY;
+------+
| DAY |
+------+
| 14 |
+------+
1 row in set (0.00 sec)
从datetime中提取day_hour：
mysql> SELECT EXTRACT(DAY_HOUR FROM '2017-07-14 09:04:44') DAYHOUR;
+---------+
| DAYHOUR |
+---------+
| 1409 |
+---------+
1 row in set (0.00 sec)
从datetime中提取day_microsecond：
mysql> SELECT EXTRACT(DAY_MICROSECOND FROM '2017-07-14 09:04:44') DAY_MS;
+----------------+
| DAY_MS |
+----------------+
| 14090444000000 |
+----------------+
1 row in set (0.00 sec)
从datetime中提取day_minute：
mysql> SELECT EXTRACT(DAY_MINUTE FROM '2017-07-14 09:04:44') DAY_M;
+--------+
| DAY_M |
+--------+
| 140904 |
+--------+
1 row in set (0.00 sec)
从datetime中提取day_second ：
mysql> SELECT EXTRACT(DAY_SECOND FROM '2017-07-14 09:04:44') DAY_S;
+----------+
| DAY_S |
+----------+
| 14090444 |
+----------+
1 row in set (0.00 sec)
从datetime提取小时数：
mysql> SELECT EXTRACT(HOUR FROM '2017-07-14 09:04:44') HOUR;
+------+
| HOUR |
+------+
| 9 |
+------+
1 row in set (0.00 sec)
从datetime中提取hour_microsecond：
mysql> SELECT EXTRACT(HOUR_MICROSECOND FROM '2017-07-14 09:04:44') HOUR_MS;
+-------------+
| HOUR_MS |
+-------------+
| 90444000000 |
+-------------+
1 row in set (0.00 sec)
从datetime中提取hour_minute：
mysql> SELECT EXTRACT(HOUR_MINUTE FROM '2017-07-14 09:04:44') HOUR_M;
+--------+
| HOUR_M |
+--------+
| 904 |
+--------+
1 row in set (0.00 sec)
从datetime中提取hour_second：
mysql> SELECT EXTRACT(HOUR_SECOND FROM '2017-07-14 09:04:44') HOUR_S;
+--------+
| HOUR_S |
+--------+
| 90444 |
+--------+
1 row in set (0.00 sec)
从datetime提取微秒：
mysql> SELECT EXTRACT(MICROSECOND FROM '2017-07-14 09:04:44') MICROSECOND;
+-------------+
| MICROSECOND |
+-------------+
| 0 |
+-------------+
1 row in set (0.00 sec)
从日期时间中提取分钟：
mysql> SELECT EXTRACT(MINUTE FROM '2017-07-14 09:04:44') MINUTE;
+--------+
| MINUTE |
+--------+
| 4 |
+--------+
1 row in set (0.00 sec)
从datetime中提取minute_microsecond：
mysql> SELECT EXTRACT(MINUTE_MICROSECOND FROM '2017-07-14 09:04:44') MINUTE_MS;
+-----------+
| MINUTE_MS |
+-----------+
| 444000000 |
+-----------+
1 row in set (0.00 sec)
从datetime中提取minute_second：
mysql> SELECT EXTRACT(MINUTE_SECOND FROM '2017-07-14 09:04:44') MINUTE_S;
+----------+
| MINUTE_S |
+----------+
| 444 |
+----------+
1 row in set (0.00 sec)
从日期时间提取月份：
mysql> SELECT EXTRACT(MONTH FROM '2017-07-14 09:04:44') MONTH;
+-------+
| MONTH |
+-------+
| 7 |
+-------+
1 row in set (0.00 sec)
从日期时间提取季度：
mysql> SELECT EXTRACT(QUARTER FROM '2017-07-14 09:04:44') QUARTER;
+---------+
| QUARTER |
+---------+
| 3 |
+---------+
1 row in set (0.00 sec)
从datetime中提取秒数：
mysql> SELECT EXTRACT(SECOND FROM '2017-07-14 09:04:44') SECOND;
+--------+
| SECOND |
+--------+
| 44 |
+--------+
1 row in set (0.00 sec)
从datetime中提取second_microsecond：
mysql> SELECT EXTRACT(SECOND_MICROSECOND FROM '2017-07-14 09:04:44') SECOND_MS;
+-----------+
| SECOND_MS |
+-----------+
| 44000000 |
+-----------+
1 row in set (0.00 sec)
从datetime提取周：
mysql> SELECT EXTRACT(WEEK FROM '2017-07-14 09:04:44') WEEK;
+------+
| WEEK |
+------+
| 28 |
+------+
1 row in set (0.00 sec)
从日期时间提取年份：
mysql> SELECT EXTRACT(YEAR FROM '2017-07-14 09:04:44') YEAR;
+------+
| YEAR |
+------+
| 2017 |
+------+
1 row in set (0.00 sec)
从datetime提取year_month：
mysql> SELECT EXTRACT(YEAR_MONTH FROM '2017-07-14 09:04:44') YEARMONTH;
+-----------+
| YEARMONTH |
+-----------+
| 201707 |
+-----------+
1 row in set (0.00 sec)
在本教程中，您学习了如何使用MySQL EXTRACT()函数来提取DATE或DATETIME值的一部分。
