如何将字符串变量转换为sql-server中的datetime变量？ [英] how convert string variable to datetime variable in sql-server?

问题描述

我比较新的sql-server;我试图将一个开始日期和结束日期从一个表单变量拉成字符串，然后将其转换为日期时间（yyyy-mm-dd）格式，我似乎找不到任何有效的东西。尝试的代码和导致的错误在下面。任何建议将不胜感激。

  declare @startdate as varchar 
 declare @enddate as varchar 
 set @ startdate = cast（@startdate as datetime）
 set @ enddate = cast（@enddate as datetime）
 
 SELECT order_date，inv_no 
从发票
其中order_date @ startdate和@enddate 
  

我不断得到的错误是：

从字符串转换datetime时转换失败。

我该如何解决？

解决方案

指定您的 varchar 的长度：

  declare @startdate as varchar（10）
 declare @enddate as varchar（10）
 set @ startdate = cast（@ startdate as datetime）
 set @ enddate = cast（@enddate as datetime）
 
 SELECT order_date，inv_no 
从发票
其中@startdate和@enddate之间的order_date 
  

I'm relatively new to sql-server; I'm trying to have a start-date and end-date pulled from a form-variable as string then convert it into datetime (yyyy-mm-dd) format and I can't seem to find anything that works. Attempted code and resulting error is below. Any advice would be appreciated.

declare @startdate as varchar
declare @enddate as varchar
set @startdate=cast(@startdate as datetime)
set @enddate=cast(@enddate as datetime)

SELECT order_date, inv_no 
from invoices 
where order_date between @startdate and @enddate

The error I keep getting is:

Conversion failed when converting datetime from character string.

How do I fix this?

解决方案

specify a length for your varchar:

declare @startdate as varchar(10)
declare @enddate as varchar(10)
set @startdate=cast(@startdate as datetime)
set @enddate=cast(@enddate as datetime)

SELECT order_date, inv_no 
from invoices 
where order_date between @startdate and @enddate

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