SQL: DATEDIFF 如果开始日期大于另一个字段中的日期

Question

我想计算出我已声明为变量的 2 个日期之间的差异，

DECLARE @start_date DATETIME
SET @start_date= '20000728'

DECLARE @end_date DATETIME
SET @end_date= '20161028'

但前提是@start_date 大于DATE_CREATED。如果不是，我想区分 DATE_CREATED 和 @end_date

我该怎么做？

我现在只有：

DATEDIFF(DAY, @start_date, @end_date) AS 'DAYS_AVAIL_RANGE'

我不确定如何合并 IF 语句来执行此操作，

感谢任何帮助，干杯！

Answer 1

你想要case:

select (case when @start_date > date_created
             then datediff(DAY, @start_date, @end_date) 
             else datediff(DAY, date_created, @end_date) 
        end) as days_avail_range

Answer 2

试试这个

 select datediff(DAY, (select max(v) from (VALUES (@start_date), (DATE_CREATED)) as value(v)) , @end_date) from yourtable

Answer 3

试试这个。这肯定会解决您的问题，因为这里为 date/time 值执行转换。

select
    case when DATEDIFF(day,convert(date,DATE_CREATED),CONVERT(date,@start_date)) > 0
        then datediff(DAY, convert(date,@start_date), convert(date,@end_date))
    else
        datediff(DAY, convert(date,DATE_CREATED), convert(date,@end_date)) 
    end

SQL: DATEDIFF 如果开始日期大于另一个字段中的日期

SQL: DATEDIFF If Start Date is greater than a date in another field

sql

sql-server

if-statement

sql-server-2012

datediff