I'm working with a database where dates are stored as 10 digit integers and where the user can query information within certain calendar date ranges. I was wondering what are the steps for converting a calendar date to a 10 digit integer for comparison with dates stored in a database.
I'm working with sql server 2000.
You need SELECT DATEADD(second, 1240494225, '19700101') to convert the number to a date and SELECT DATEDIFF(second, '19700101', #some_date) to go the other way.
Related
I have table where the date field (TimeStringID ) is in numerical format represented as the number of seconds that have past since 12:00am March 1,1980.
In SQL Server the command is DATEADD(s, CAST(TimeStringID AS numeric), '1980-03-01') AS 'StartTime'
The field 1289260817.0000000501 converts to 2021-01-07 00:00:17.000 using the above SQL Server statement.
How would I convert this for Access queries?
I believe this is the equivalent:
select dateadd("s", TimeStringId, #03/01/1980#)
I'm trying to represent a Date in symbolic format, and the goal is to do it with minimum characters with only integer or English Alphabets
What I tried is below SQL Server Query:
SELECT format(CAST(DATEDIFF(day, CAST('1900-01-01' AS DATE), CAST('2100-01-01' AS DATE)) AS INT), '00000')
This query give result 73049, which is quite good to represent a date in 5 characters for as long as two centuries. With this I can very easily get the Date which it represent, making '1900-01-01' or some other date as fixed start date, as per my Application need.
I'm looking for possibility to reduce character length further.
I am importing records from a DB2 data source into a MS SQL Server destination.
The records are coming in with the date format of 20150302/YYYYMMDD, but I only want the last 14 days based on current server date.
Can some advise on how to select based on this date format against DATEADD(d, - 1, { fn CURDATE() }) please.
Thanks!
It would be better to do this on the DB2 side, to reduce the number of records brought over.
Additionally, it's better from a performance standpoint to convert the static date into a numeric date and compare to the column in your table. Rather than convert the numeric date in your table to a actual date type for comparison.
where numdate >= int(replace(char(current_date - 14 days,iso),'-',''))
Doing it this way will allow you to take advantage of an index over numdate. In addition, DB2 will only need to perform this conversion once.
Depending on your platform & version, you may have an easier way to convert from a date data type to a numeric date. But the above works on DB2 for i and should work on most (all?) DB2 versions and platforms.
You may find it worthwhile to create a UDF to do this conversion for you.
If you want logic in SQL Server, then you are in luck, because you can just convert the YYYYMMDD format to a date:
where cast(datecol as date) >= cast(getdate() - 14 as date)
(This assumes no future dates.)
If you want to do this on the DB2 side, you can use to_date():
where to_date(datecol, 'YYYYMMDD') >= current date - 14 days
I am casting DateTime field to Time by using CAST Syntax.
select CAST([time] as time) as [CSTTime]
DateTime
2015-03-19 00:00:00.000
Present Output : Time
03:05:36.0000000
I need only HH:MM:SS and not Milliseconds or 0000's
How to filter or Cast it to exact HH:MM:SS Format.
Time is not stored with its display format in SQL Server.
Therefore, from the user perspective, you can say that it has no format.
Of course, that's not completely accurate since it does have a storage format, but as an average user you can't really use it.
This is true for all date and time data types:
Date, DateTimeOffset, DateTime2, SmallDateTime, DateTime and Time.
If you need a format then you don't need to cast to time but to a char. Use Convert to get the char you need:
SELECT CONVERT(char(10), [time], 108) as CSTTime
Here is some background data if you're interested:
In this article published in 2000 the writer explains in depth how SQL Server treats dates and times. I doubt if anything significant changed between 2000 and 2015 in the way SQL Server stores date, time and datetime values internally.
Here are the relevant quotes, if you don't want to read all of it:
So how does SQL Server internally store the dates? It uses 8 bytes to store a datetime value—the first 4 for the date and the second 4 for the time. SQL Server can interpret both sets of 4 bytes as integers.
........
........
SQL Server stores the second integer for the time as the number of clock ticks after midnight. A second contains 300 ticks, so a tick equals 3.3 milliseconds (ms).
since time is actually stored as a 4 byte integer, it really doesn't have a format as an integral part of the data type.
You might also want to check out this article for a more detailed explanation with code samples.
You can achieve it with CAST just simple use TIME(0) datatype in following:
SELECT CAST('2015-03-19 01:05:06.289' AS TIME(0))
OUTPUT:
01:05:06
SQL Server 2008:
select cast(MyDate as time) [time] from yourtable
Earlier versions:
select convert(char(5), MyDate , 108) [time] from yourtable
Other Options:
SELECT CONVERT(VARCHAR(20), GETDATE(), 114)
The simplest way to get the time from datetime without millisecond stack is:
SELECT CONVERT(time(0),GETDATE())
Hour and Minute
SELECT substring(CONVERT(VARCHAR, GETDATE(), 108),0,6) AS Time
I've been doing a convert(varchar,datefield,112) on each date field that I'm using in 'between' queries in SQL server to ensure that I'm only accounting for dates and not missing any based on the time part of datetime fields.
Now, I'm hearing that the converts aren't indexable and that there are better methods, in SQL Server 2005, to compare the date part of datetimes in a query to determine if dates fall in a range.
What is the optimal, indexable, method of doing something like this:
select * from appointments
where appointmentDate>='08-01-2008' and appointmentDate<'08-15-2008'
The best way to strip the time portion of a datetime field is using datediff and dateadd functions.
DateAdd(day, datediff(day,0, MydateValue), 0)
This takes advantedge of the fact that SQL Server stores dates as two integers, one representing the number of days since day "0" - (1 jan 1900), and the second one which represents the number of ticks (each tick is about 3.33 ms) since midnight (for the time) *.
the formula above simply has to only read the first integer. There is no conversion or processing required, so it is extremely fast.
To make your queries use an index... use this formula on the input filtering parameters first, or on the "other" side of the equal sign from the tables date time field, so that the query optimizer does not have to run the calculation on every datetime field in the table to determine which rows satisfy the filter predicate. This makes your search argument "SARG-able" (Search ARGument)
Where MyDateTimeColumn > DateAdd(day,
datediff(day,0, #MydateParameter), 0) -- SARG-able
rather than
Where DateAdd(day, datediff(day,0,
MyDateTimeColumn ), 0) > #MydateParameter -- Not SARG-able
* NOTE. Internally, the second integer (the time part) stores ticks. In a day there are 24 x 60 X 60 X 300 = 25,920,000 ticks (serendipitously just below the max value a 32 bit integer can hold). However, you do not need to worry about this when arithmetically modifying a datetime... When adding or subtracting values from datetimes you can treat the value as a fraction as though it was exactly equal to the fractional portion of a day, as though the complete datetime value was a floating point number consisting of an integer portion representing the date and the fractional portion representing the time). i.e.,
`Declare #Dt DateTime Set #Dt = getdate()
Set #Dt = #Dt + 1.0/24 -- Adds one hour
Select #Dt
Set #Dt = #Dt - .25 -- Moves back 6 hours
Select #Dt`
Converting numeric types to string values (a type of Boxing) is not the best performing method of doing what you are looking for. Its not really about index-able, because the actual column type is date time.
If you are looking for the best way query for dates, then your example is right, but you may want to take into account the 3 ms precision difference in MSSQL. It can mean that records from one day can show up in another day's result.
This
select * from appointments where appointmentDate>='08-01-2008' and appointmentDate<'08-15-2008'
Should be this
select * from appointments where appointmentDate>='08-01-2008' and appointmentDate<='08-14-2008 23:59:59.996'
It's correct - doing the conversion will execute the conversion for every row queried. It's better to leave the date columns as dates, and pass in your where clauses as dates:
select * from appointments where appointmentdate between
'08/01/2008' AND '08/16/2008'
Note: Leaving off the time means midnight (00:00.000), so you will include all times for 08/01, and all times from 08/15, and anything that is exactly 08/16/2008 00:00:00
Have a computed persisted column calculate the expression you need. If columns are computed and persisted, they can also be indexed.
There is also the way described at http://www.stillnetstudios.com/comparing-dates-without-times-in-sql-server/
SELECT CAST(FLOOR(CAST( getdate() AS float )) AS datetime)