试试这个

Cast('7/7/2011' as datetime)

and

Convert(DATETIME, '7/7/2011', 101)

有关详细信息，请参阅CAST和CONVERT (Transact-SQL)。

If you want SQL Server to try and figure it out, just use CAST CAST('whatever' AS datetime) However that is a bad idea in general. There are issues with international dates that would come up. So as you've found, to avoid those issues, you want to use the ODBC canonical format of the date. That is format number 120, 20 is the format for just two digit years. I don't think SQL Server has a built-in function that allows you to provide a user given format. You can write your own and might even find one if you search online.

SQL Server(2005, 2000, 7.0)没有任何灵活的，甚至是不灵活的方法来获取任意结构的字符串格式的datetime并将其转换为datetime数据类型。

所谓“随意”，我指的是“一种写作者(虽然可能不是你、我或地球另一边的人)认为是直观和完全明显的形式。”坦率地说，我不确定是否有这样的算法。

用这个:

SELECT convert(datetime, '2018-10-25 20:44:11.500', 121) -- yyyy-mm-dd hh:mm:ss.mmm

转换代码请参考官方文档中的表格。

在MSSQL中隐式转换字符串到日期时间

create table tmp 
(
  ENTRYDATETIME datetime
);

insert into tmp (ENTRYDATETIME) values (getdate());
insert into tmp (ENTRYDATETIME) values ('20190101');  --convert string 'yyyymmdd' to datetime


select * from tmp where ENTRYDATETIME > '20190925'  --yyyymmdd 
select * from tmp where ENTRYDATETIME > '20190925 12:11:09.555'--yyyymmdd HH:MIN:SS:MS

dateadd(day,0,'10/15/2008 10:06:32 PM')