日期的一些杂七杂八的东西

---===hubin===---

做这行的什么东西都要会,各种各样的数据库都要知道些.
SQLServer2005

===时间===
The following examples use the six SQL Server system functions
that return current date and time to return the date, time, or both.
The values are returned in series;
therefore, their fractional seconds might be different.

A. Getting the current system date and time

SELECT SYSDATETIME()
    ,SYSDATETIMEOFFSET()
    ,SYSUTCDATETIME()
    ,CURRENT_TIMESTAMP
    ,GETDATE()
    ,GETUTCDATE();

Here is the result set.

SYSDATETIME() 2007-04-30 13:10:02.0474381

SYSDATETIMEOFFSET()2007-04-30 13:10:02.0474381 -07:00

SYSUTCDATETIME() 2007-04-30 20:10:02.0474381

CURRENT_TIMESTAMP 2007-04-30 13:10:02.047

GETDATE() 2007-04-30 13:10:02.047

GETUTCDATE() 2007-04-30 20:10:02.047

B. Getting the current system date

SELECT CONVERT (date, SYSDATETIME())
    ,CONVERT (date, SYSDATETIMEOFFSET())
    ,CONVERT (date, SYSUTCDATETIME())
    ,CONVERT (date, CURRENT_TIMESTAMP)
    ,CONVERT (date, GETDATE())
    ,CONVERT (date, GETUTCDATE());

Here is the result set.

SYSDATETIME() 2007-05-03

SYSDATETIMEOFFSET() 2007-05-03

SYSUTCDATETIME() 2007-05-04

CURRENT_TIMESTAMP 2007-05-03

GETDATE() 2007-05-03

GETUTCDATE() 2007-05-04

C. Getting the current system time

SELECT CONVERT (time, SYSDATETIME())
    ,CONVERT (time, SYSDATETIMEOFFSET())
    ,CONVERT (time, SYSUTCDATETIME())
    ,CONVERT (time, CURRENT_TIMESTAMP)
    ,CONVERT (time, GETDATE())
    ,CONVERT (time, GETUTCDATE());

Here is the result set.

SYSDATETIME() 13:18:45.3490361

SYSDATETIMEOFFSET()13:18:45.3490361

SYSUTCDATETIME() 20:18:45.3490361

CURRENT_TIMESTAMP 13:18:45.3470000

GETDATE() 13:18:45.3470000

GETUTCDATE() 20:18:45.3470000

上面是MSDN上copy来的,
这里我要加的是
select getDate()-2;
'-2',也没有说2是什么,但是结果是今天-2天,就是前天的前天.
会很有用.

MSDN上的地址http://msdn.microsoft.com/en-us/library/aa258266(SQL.80).aspx
现在的日期:2010-10-12_14:05:09