c# - sqlite 添加 x 天至今(x 存储在表中)

Question

我需要在 sqlite (c# 应用程序)中执行类似的操作:

select DATE(XDATE,'+XDAYS day') from TABLE

XDATE和XDAYS字段是字符串类型，存储在“TABLE”表中。

有人理解我并可以帮助我吗？谢谢。

Answer 1

使用 SqlLite DateTime 修饰符 ( https://www.sqlite.org/lang_datefunc.html )

date(timestring, modifier, modifier, ...)

The time string can be followed by zero or more modifiers that alter date and/or time. Each modifier is a transformation that is applied to the time value to its left. Modifiers are applied from left to right; order is important. The available modifiers are as follows.

NNN days

NNN hours

NNN minutes

NNN.NNNN seconds

NNN months

NNN years

start of month start of year start of day weekday N unixepoch

localtime utc

例如: SELECT date('现在','月初','+1 个月','-1 天');

CREATE TABLE [theDates] (
  [d] VARCHAR(100)  NULL,
  [diff] varchar(100)  NULL
)


insert into [TheDates] VALUES ('now', '-10 day')   

Select d, diff, date([d], [diff]) from [TheDates]


d             diff        date([d], [diff])
-------------------------------------------
now           -10 day     2015-06-02

如果你有数字数据

insert into [TheDates] VALUES ('now', -10)   

Select d, diff, date([d], ([diff] || ' day')) from [TheDates]


d             diff        date([d], ([diff] || ' day'))
-------------------------------------------------------
now           -10 day     2015-06-02