SQL-Server Time数据类型

Question

From what i've read so far, the data type time in sql server (starting with 2008) should be able to store the time in a HH:MM format. Then I tried this myself with the following simple exercise:

create table #mytable (id int, lat float, lon float, trajectory_id int, theTime time(5))
insert into #mytable values 
 ('1','15.8','17.1','162','10:01'),
 ('2','11.5','59.7','162','10:02'),
 ('3','16.4','79.9','162','10:03'),
 ('4','29.5','10.3','180','11:12'),
 ('5','58.2','11.1','180','11:13'),
 ('6','54.5','14.1','180','11:14'),
 ('7','14.9','15.2','166','13:40'),
 ('8','15.0','13.1','166','13:42')

My expected result for the column theTime was:

theTime
10:01
10:02
10:03
11:12
11:13
11:14
13:40
13:42

What I got instead was:

theTime
10:01:00.00000
10:02:00.00000
10:03:00.00000
11:12:00.00000
11:13:00.00000
11:14:00.00000
13:40:00.00000
13:42:00.00000

Sure, I could select left(theTime, 5) and get the expected result. But i'm wondering how I could insert it directly in the desired format.

I want to use a built in function and not to store the numbers in an int for HH , MM , SS as one might have used before sql server 2005.

Using sql server 2012. Thanks

Answer 1

This is too long for a comment.

You seem confused by the difference between internal formats and display formats. TIME is a data type built into the language. When it prints out, it prints out with hours, minutes, and seconds. That is how the data type prints out, in the same way the SQL Server does not put commas in integers bigger than 1000 and uses an appropriate symbol for the decimal place. (Or for that matter prints out integers in base 10 rather than the binary format as they are actually stored.)

When you say TIME(5) you are saying that you want at least 5 decimal places of precision for fractional seconds : HH:MM:SS.SSSSS. There is no option for removing seconds altogether from the time type.

If you want to print it out in a particular format, use convert() , cast() , or format() . Happily, cast() works quite well for times . The plethora of inscrutable numeric codes for date/time are more applicable to dates, than times.

When you do left(thetime, 5) then you are implicitly converting time to a string and taking the first five characters. This seems to meet your needs. I would suggest that you just build this into your table:

alter table #mytable add thetime_hhmm as (left(thetime, 5));

Then you can use thetime_hhmm to get the value as a string with the format you want.

Answer 2

You can't control the format that a data type is stored as. Your time data is actually being stored as a bunch of bits -- 0's and 1's -- and it's only being displayed like 10:01:00.00000 in your query analyzer.

If you want to show it in another format, then you have to convert it to a text data type like varchar, but this is usually something your UI layer should handle, not your data layer.