How to convert DateTime to a number with a precisi

问题:

Both queries below translates to the same number

SELECT CONVERT(bigint,CONVERT(datetime,'2009-06-15 15:00:00'))
SELECT CAST(CONVERT(datetime,'2009-06-15 23:01:00') as bigint)

Result

39978
39978

The generated number will be different only if the days are different. There is any way to convert the DateTime to a more precise number, as we do in .NET with the .Ticks property?

I need at least a minute precision.

回答1:

Well, I would do it like this:

select datediff(minute,'1990-1-1',datetime)

where '1990-1-1' is an arbitrary base datetime.

回答2:

SELECT CAST(CONVERT(datetime,'2009-06-15 23:01:00') as float)

yields 39977.9590277778

回答3:

DECLARE @baseTicks AS BIGINT;
SET @baseTicks = 599266080000000000; --# ticks up to 1900-01-01

DECLARE @ticksPerDay AS BIGINT;
SET @ticksPerDay = 864000000000;

SELECT CAST(@baseTicks + (@ticksPerDay * CAST(GETDATE() AS FLOAT)) AS BIGINT) AS currentDateTicks;

回答4:

If the purpose of this is to create a unique value from the date, here is what I would do

DECLARE @ts TIMESTAMP 
SET @ts = CAST(getdate() AS TIMESTAMP)
SELECT @ts

This gets the date and declares it as a simple timestamp

回答5:

Use DateDiff for this:

DateDiff (DatePart, @StartDate, @EndDate)

DatePart goes from Year down to Nanosecond.

More here.. http://msdn.microsoft.com/en-us/library/ms189794.aspx

回答6:

CAST to a float or decimal instead of an int/bigint.

The integer portion (before the decimal point) represents the number of whole days. After the decimal are the fractional days (i.e., time).

回答7:

You can use T-SQL to convert the date before it gets to your .NET program. This often is simpler if you don't need to do additional date conversion in your .NET program.

DECLARE @Date DATETIME = Getdate()
DECLARE @DateInt INT = CONVERT(VARCHAR(30), @Date, 112)
DECLARE @TimeInt INT = REPLACE(CONVERT(VARCHAR(30), @Date, 108), ':', '')
DECLARE @DateTimeInt BIGINT = CONVERT(VARCHAR(30), @Date, 112) + REPLACE(CONVERT(VARCHAR(30), @Date, 108), ':', '')
SELECT @Date as Date, @DateInt DateInt, @TimeInt TimeInt, @DateTimeInt DateTimeInt

---

Date                    DateInt     TimeInt     DateTimeInt
------------------------- ----------- ----------- --------------------
2013-01-07 15:08:21.680 20130107    150821      20130107150821

回答8:

And here is a bigint version of the same

DECLARE @ts BIGINT 
SET @ts = CAST(CAST(getdate() AS TIMESTAMP) AS BIGINT)
SELECT @ts