减去 2 个日期得到天数

Question

我正在使用优势 sql 数据库，并尝试减去 2 个日期以获得天数。我认为在 ADV SQL 中你可以只减去日期，它会给你天数。

((完成) - (开始日期))

1-23-19 - 1-3-19 = 20 天

Answer 1

如果两者都是DATE 类型，您可以直接在ADS SQL 中减去日期。如果它们都是TIMESTAMP，则可以使用TIMESTAMPDIFF() 和TSI_SQL_DAYS 作为间隔。如果一个是DATE，另一个是TIMESTAMP，则需要将TIMESTAMP转换为DATE，然后直接相减即可。

以下是所有这三种选择的示例。

两列都是DATE:

create table Test (ID integer, StartDate Date, Completed Date);
insert into Test values (1, '2019-01-01', '2019-01-31');
insert into Test values (2, '2019-01-01', '2018-02-28');
select id, startdate, completed, completed - startdate as days from test;

输出：

id  startdate    completed    days      
--- -----------  -----------  ----
1   01/01/2019   01/31/2019     30
2   01/01/2019   02/28/2019     58

两列都是TIMESTAMP：

create table Test2 (ID integer, StartDate TimeStamp, Completed TimeStamp);
insert into Test2 (ID, StartDate, Completed)
  values (1, CreateTimeStamp(2019, 1, 1, 0, 0, 0, 1),
             CreateTimeStamp(2019, 1, 31, 0, 0, 0, 1));
insert into Test2 (ID, StartDate, Completed)
  values (2, CreateTimeStamp(2019, 1, 1, 0, 0, 0, 1),
             CreateTimeStamp(2019, 2, 28, 0, 0, 0, 1));
select id, startdate, completed, 
  TimeStampDiff(SQL_TSI_DAY, StartDate, Completed) as days from test2;

输出：

id  startdate    completed    days      
--- -----------  -----------  ----
  1 01/01/2019   01/31/2019     30
  2 01/01/2019   02/28/2019     58

有一个DATE 和一个TIMESTAMP：

create table Test3 (ID integer, StartDate TimeStamp, Completed Date);
insert into Test3 (ID, StartDate, Completed)
  values (1, CreateTimeStamp(2019, 1, 1, 0, 0, 0, 1), '2019-01-31');
insert into Test3 (ID, StartDate, Completed)
  values (2, CreateTimeStamp(2019, 1, 1, 0, 0, 0, 1), '2019-02-28');
select id, startdate, completed, 
  Completed - Cast(StartDate AS SQL_DATE) as days from test3;

输出：

id  startdate    completed    days      
--- -----------  -----------  ----
  1 01/01/2019   01/31/2019     30
  2 01/01/2019   02/28/2019     58

Answer 2

我认为timestampdiff() 应该做你想做的事：

timestampdiff(SQL_TSI_DAY, startdate, completed)

Answer 3

这是一个非常不寻常的数据库，可供您提问 - 文档建议 (https://devzone.advantagedatabase.com/dz/webhelp/advantage10/index.html?master_supported_scalar_functions.htm) 您需要：

TIMESTAMPDIFF(SQL_TSI_DAY,completed, startdate)

编辑：包括演员表

TIMESTAMPDIFF(SQL_TSI_DAY,completed, cast(startdate as SQL_TIMESTAMP))

文档：

TIMESTAMPDIFF(时间间隔，timestamp1，timestamp2)

根据减去时间戳1返回整数间隔数 从时间戳2。支持的间隔值是：SQL_TSI_FRAC_SECOND， SQL_TSI_SECOND、SQL_TSI_MINUTE、SQL_TSI_HOUR、SQL_TSI_DAY、 SQL_TSI_WEEK、SQL_TSI_MONTH、SQL_TSI_QUARTER、SQL_TSI_YEAR。