mysql中TIMESTAMPDIFF案例详解

1.  syntax

timestampdiff(unit,begin,end); 根据单位返回时间差,对于传入的begin和end不需要相同的数据结构,可以存在一个为date一个datetime

2. unit

支持的单位有

• microsecond
• second
• minute
• hour
• day
• week
• month
• quarter
• year

3. example

下面这个例子是对于timestampdiff最基本的用法，

• 3.1 求 2017-01-01 - 2017-02-01 之间有几个月

select timestampdiff(month, '2017-01-01', '2017-02-01') as  result;

+--------+
| result |
+--------+
| 1 |
+--------+
1 row in set (0.00 sec)

• 3.2 求 2017-01-01 - 2017-02-01 之间有几天

select timestampdiff(day, '2017-01-01', '2017-02-01') as  result;

+--------+
| result |
+--------+
| 31 |
+--------+
1 row in set (0.00 sec)

•  3.3 求 2017-01-01 08: 00:00 - 2017-01-01 08: 55:00 之间有几分钟

select timestampdiff(minute, '2017-01-01 08:00:00', '2017-01-01 08:55:00') result;

+--------+
| result |
+--------+
| 55 |
+--------+
1 row in set (0.00 sec)

•  3.4 求 2017-01-01 08: 00:00 - 2017-01-01 08: 55:33 之间有几分钟

select timestampdiff(minute, '2017-01-01 08:00:00', '2017-01-01 08:55:33') result;

+--------+
| result |
+--------+
| 55 |
+--------+
1 row in set (0.00 sec)

•  3.5 对于day， minute进行计算diff时，会直接将相对应的day，minute相减

• 3.6 对于 second 会怎样计算呢

select timestampdiff(second, '2017-01-01 08:00:00', '2017-01-01 08:55:33') result;

55 * 60 + 33 = 3333
+--------+
| result |
+--------+
|   3333 |
+--------+
1 row in set (0.00 sec)

• 3.7 如何求数据库中两个date字段的diff
  • 3.7.1  建表

    create table demo (id int auto_increment primary key, start_time date not null, end_time date not null);
    query ok, 0 rows affected (0.10 sec)

  • 3.7.2  添加数据

    insert into demo(start_time, end_time)
    values('1983-01-01', '1990-01-01'),
    ('1983-01-01', '1989-06-06'),
    ('1983-01-01', '1985-03-02'),
    ('1983-01-01', '1992-05-05'),
    ('1983-01-01 11:12:11', '1995-12-01');

  • 3.7.3 直接query数据

    select * from demo;
    +----+------------+------------+
    | id | start_time | end_time |
    +----+------------+------------+
    | 1 | 1983-01-01 | 1990-01-01 |
    | 2 | 1983-01-01 | 1989-06-06 |
    | 3 | 1983-01-01 | 1985-03-02 |
    | 4 | 1983-01-01 | 1992-05-05 |
    | 5 | 1983-01-01 | 1995-12-01 |
    +----+------------+------------+
    5 rows in set (0.00 sec)

  • 3.7.4 计算duration

    select *, timestampdiff(year, start_time, end_time) as duration from demo;
    
    +----+------------+------------+----------+
    | id | start_time | end_time | duration |
    +----+------------+------------+----------+
    | 1 | 1983-01-01 | 1990-01-01 | 7 |
    | 2 | 1983-01-01 | 1989-06-06 | 6 |
    | 3 | 1983-01-01 | 1985-03-02 | 2 |
    | 4 | 1983-01-01 | 1992-05-05 | 9 |
    | 5 | 1983-01-01 | 1995-12-01 | 12 |
    +----+------------+------------+----------+
    5 rows in set (0.00 sec)

  • 3.7.5 其他应用

    select *, if(timestampdiff(year, end_time, current_timestamp())< 26 ,'< 26','>= 26') as result from demo;
    
    +----+------------+------------+--------+
    | id | start_time | end_time | result |
    +----+------------+------------+--------+
    | 1 | 1983-01-01 | 1990-01-01 | >= 26 |
    | 2 | 1983-01-01 | 1989-06-06 | >= 26 |
    | 3 | 1983-01-01 | 1985-03-02 | >= 26 |
    | 4 | 1983-01-01 | 1992-05-05 | < 26 |
    | 5 | 1983-01-01 | 1995-12-01 | < 26 |
    +----+------------+------------+--------+
    5 rows in set (0.00 sec)

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