I'm rather new to ASP.NET and SQL, so I'm having a tough time trying to figure out how to compare two time columns. I have a timestamped column and then a Now() column in an .mdb database. I need to have a gridview display records that are "Greater than or equal to 3 hours" from the timestamp. Any idea how I can accomplish this?
The Transact-SQL timestamp data type is a binary data type with no time-related values.
So to answer your question: Is there a way to get DateTime value from timestamp type column?
The answer is: No
You need another column of datetime2 type and use > operator to for comparison. You might want to set default value of getutcdate() to set it when each row is inserted.
UPDATE:
Since the column is of datetime type and not timestamp type (there is a type in SQL Server called timestamp, hence the confusion) you can just do
WHERE [TimeCalled] <= DATEADD(hour, -3, GETDATE())
Make sure your server is running in the same timezone as your code. It may be safer to store all dates in UTC. In that case use GETUTCDATE instead on GETDATE
Timestamps are generally used to track changes to records, and are updated every time the record is changed. If you want to store a specific value you should use a datetime field.
If you're using a DateTime Column and you want the result in TSQL try
DATEDIFF(Hour, 'Your DateTime Column here', 'pass Now() here' )
try to execute this example in TSQL:
select DATEDIFF(Hour, '2012-11-10 00:00:59.900', '2012-11-10 05:01:00.100')
Related
I am using below condition to truncate date in postgres
to_date(to_char(trunc(appointment_date),'YYYYMMDD')||appointment_end_time,''YYYYMMDDHH24:MI:SS')AS tq
How I can use this in postgres ?
Strange data typing, sometimes requires strange, looking at least, queries. Try (see fiddle)
date_trunc('day',appointment_date)
+ substr(appoinment_end,12)::interval
As your to_char() call uses the format 'HH24:MI:SS' for the "time" column, you can cast that column directly to a time value, e.g. using the :: operator: appointment_end_time::time.
To build a new timestamp from the date part of the appointment_date and the time value, just add them:
appointment_date::date + appointment_end_time::time
So first the timestamp is converted to a date (that does not have a time), and then the time value is added to that, which yields a timestamp.
Note that to_date() returns a date so your code would remove the just added time part again. You would need to use to_timestamp() if you really want a timestamp as the result.
To answer the question's title "how to truncate date in Postgres?" (which in reality refers to a timestamp not a date): you can either cast it to a date (see above) or you can use date_trunc() (not trunc()) with a unit to which it should be truncated. However, date_trunc returns a timestamp not a date value, so you couldn't add a time to the result.
I am extracting three values (server, region, max(date)) from my postgresql> But I want to extract an additional 4th field which should be the numerical addition of 1 to 3rd field. I am unable to use date add function as in the database date field is defined as an integer.
date type in DB
date|integer|not null
tried using cast and date add function
MAX(s.date)::date + cast('1 day' as interval)
Error Received
ERROR: cannot cast type integer to date
Required output
select server, region, max(alarm_date), next date from table .....
testserver, europe, 20190901, 20190902
testserver2, europe, 20191001, 20191002
next date value should be the addition to alarm_date
To convert an integer like 20190901 to a date, use something like
to_date(CAST(s.date AS text), 'YYYYMMDD')
It is a bad idea to store dates as integers like that. Using the date data type will prevent corrupted data from entering the database, and it will make all operations natural.
First solution that came to my mind:
select (20190901::varchar)::date + 1
Which output 2019-09-02 as type date.
Other solutions can be found here.
I would like to get DATE format like in the title (yyyy-mm) from getdate() , in order to use it in where clause to get < and > dates from the one i formatted .So far i found almost everybody uses convert(varchar(10),getdate(),120) but that's varchar and it cant be check with < and > right ? So can someone help me to make a Date in format yyyy-mm or it's impossible ?
Why can't VARCHAR be compared using > and < operators? So long as you have a character string in an appropriate format, you can compare it just fine. For instance, CONVERT(VARCHAR(10), GETDATE(), 120) returns an ODBC Canonical format date, as "YYYY-MM-DD". This can obviously be compared using > and < to obtain correct results.
However, you would generally not want to do this in a database. Predicate such as this:
WHERE CONVERT(VARCHAR(10), [DateColumn], 120) >= '2018-02-26'
are considered "non-SARGable", and cannot use an index. This means that the server will apply brute force conversions to the underlying columns prior to the comparison, resulting in Index Scans or Table Scans, depending upon your schema.
For the vast majority of situations, you want the column to be used as an operand without any kind of conversion beforehand. Thus, the predicate should be expressed as:
WHERE [DateColumn] >= '2018-02-26'
This will result in an implicit cast of the '2018-02-26' operand into Date or DateTime (whatever the column type is), and this can use an index.
The absolute best would be an explicit cast such as this:
WHERE [DateColumn] >= CAST('2018-02-26' AS DATETIME)
This way, there is no room for mistakes, implicit conversions, or non-SARGable predicates.
Put simply, you do not want to do this in the way you are asking.
To look for records that match a specific year and month, simply use two where criteria in this manner:
declare #SomeDate date = '20180114'; -- This is any date.
-- This gets the first day of the month of the date above.
declare #MonthStart date = dateadd(month,datediff(month,0,#SomeDate),0);
-- This gets the first day of the following month of the date above.
declare #NextMonthStart date = dateadd(month,datediff(month,0,#SomeDate)+1,0);
select cols
from tables
where DateCol >= #MonthStart
and DateCol < #NextMonthStart;
if you have an existing datetime you should compare it against another time, using between for example. Why do you want to do a string comparison
I am trying to fix a query that has come to light in SSRS after the new year. We have an input that comes from another application. It grabs a date and stores it as varchar. The SSRS report then fetches the top 100 'dates' but when 2017 dates have come around, this are not in the top 100.
The existing query is as follows
SELECT DISTINCT TOP (100)
FROM DenverTempData
ORDER by BY Date DESC
The date is stored as VARCHAR. So obviously this query doesn't grab a value such as 01012017 as being a top 100 (over values likes 12312016). I thought maybe I can simply change the datatype on this column to datetime. But the information comes from a flat file and is converted, so it's a little more difficult that that. So I'm hoping to do a select of the distinct top 100 while converting the date column to datetime or just date and grabbing the last 100 dates.
Can someone help with the query syntax? I'm thinking a cast to convert varchar to date, but how do I format with distinct top 100? I'm simply looking to retrieve the last 100 dates in chronological order from a column that is stored as varchar but contains a string representing a date.
Hopefully that makes sense
It is always a bad idea to store a date as string. This is highly culture specific!
You can cast your formatted string-date to a real date like this:
DECLARE #DateMMDDYYYY VARCHAR(100)='12312016';
SELECT CONVERT(DATE,STUFF(STUFF(#DateMMDDYYYY,5,0,'-'),3,0,'-'),110)
After the conversion your sorting (and therefore the TOP 100) should work as expected.
My strong advise: Try to store your dates in a column of a real date type to avoid such hassel!
SELECT DISTINCT TOP 100 (CAST(VarcharColumn as Date) as DateColumn)
FROM TABLE
Order by DateColumn desc
I am currently dealing with a slightly strange relation layout. The relation contains several fields, two of them, datetimeA and datetimeB are used to hold a datetime value.
I am not sure why it was set up this way, but datetimeA is used to store the date components with all of the time components being 00:00:00.0 while datetimeB is used to store the time component with all of the date components as 1970-01-01.
I am creating a simple reporting interface which uses this table and I need to extract the date from datetimeA, the time from datetimeB and join them into a new datetime. If possible I would like to make this happen in the query run against the database.
An ideal solution would be something similar to the datepart function but with 'date' and 'time' parts.
This is SQL Server TSQL, but the date functions appear to be more or less the same in both products. I'm not sure how Sybase handles date literals so you might need to change them to get this example to work:
declare
#date datetime = '2013-02-15T00:00:00',
#time datetime = '1970-01-01T15:15:15'
select dateadd(ss, datediff(ss, '19700101', #time), #date)