Ignore Time element of DateTime?

P

Paolo

I have a series of queries which select transactions (using a Transaction
date) within a specified date range, where the start and end dates
(inclusive) are selected from a DateTimePicker control thus:

DateTime qryStart;
DateTime qryEnd;
.....
qryStart = dtmpickFrom.Value;
qryEnd = dtmpickTo.Value;

var query =
from trans in dataSet.Transaction
where ((trans.T_Date >= qryStart)
&& (trans.T_Date <= qryEnd)) ....

I've just done my analysis for January 2009. I have a number of transactions
with dates of 01/01/2009 then more with later dates. I'm finding that with
qryStart = 01/01/2009 the transactions with that date are being omitted from
the analysis. Looking at qryStart in the debugger it shows '01/01/09
14:49:52' (where the time reflects the time at which I selected the date in
the DateTime Picker to do the analysis.) It just so happens that the
transactions with a date of 01/01/09 all have times earlier than 14:49:52 so,
presumably, this explains why they don't appear in the analysis.

I don't actually use the time part of the DateTime variables so is there any
way I can get the queries to ignore it?
 
K

Ken Foskey

I have a series of queries which select transactions (using a
Transaction date) within a specified date range, where the start and end
dates (inclusive) are selected from a DateTimePicker control thus:

DateTime qryStart;
DateTime qryEnd;
.....
qryStart = dtmpickFrom.Value;
qryEnd = dtmpickTo.Value;

var query =
from trans in dataSet.Transaction
where ((trans.T_Date >= qryStart)
&& (trans.T_Date <= qryEnd)) ....

I've just done my analysis for January 2009. I have a number of
transactions with dates of 01/01/2009 then more with later dates. I'm
finding that with qryStart = 01/01/2009 the transactions with that date
are being omitted from the analysis. Looking at qryStart in the debugger
it shows '01/01/09 14:49:52' (where the time reflects the time at which
I selected the date in the DateTime Picker to do the analysis.) It just
so happens that the transactions with a date of 01/01/09 all have times
earlier than 14:49:52 so, presumably, this explains why they don't
appear in the analysis.

I don't actually use the time part of the DateTime variables so is there
any way I can get the queries to ignore it?
Click to expand...



add 1 day timespan and use < operator.
 
G

Göran Andersson

Paolo said:
I have a series of queries which select transactions (using a Transaction
date) within a specified date range, where the start and end dates
(inclusive) are selected from a DateTimePicker control thus:

DateTime qryStart;
DateTime qryEnd;
.....
qryStart = dtmpickFrom.Value;
qryEnd = dtmpickTo.Value;

var query =
from trans in dataSet.Transaction
where ((trans.T_Date >= qryStart)
&& (trans.T_Date <= qryEnd)) ....

I've just done my analysis for January 2009. I have a number of transactions
with dates of 01/01/2009 then more with later dates. I'm finding that with
qryStart = 01/01/2009 the transactions with that date are being omitted from
the analysis. Looking at qryStart in the debugger it shows '01/01/09
14:49:52' (where the time reflects the time at which I selected the date in
the DateTime Picker to do the analysis.) It just so happens that the
transactions with a date of 01/01/09 all have times earlier than 14:49:52 so,
presumably, this explains why they don't appear in the analysis.

I don't actually use the time part of the DateTime variables so is there any
way I can get the queries to ignore it?
Click to expand...

No, you can't, a DateTime value always has a time component. However,
you can set the time component to be zero:

qryStart = dtmpickFrom.Value.Date;
qryEnd = dtmpickTo.Value.Date;

If you want the end date to be inclusive, you should add one day to it:

qryEnd = dtmpickTo.Value.Date.AddDays(1);

In the query you should use the < operator to compare the end date. The
< operator is the exact complement to the >= operator, so that you will
get time ranges where no record will appear in two consecutive ranges.

var query =
from trans in dataSet.Transaction
where ((trans.T_Date >= qryStart)
&& (trans.T_Date < qryEnd)) ....
 
M

Mr. Arnold

Paolo said:
I have a series of queries which select transactions (using a Transaction
date) within a specified date range, where the start and end dates
(inclusive) are selected from a DateTimePicker control thus:

DateTime qryStart;
DateTime qryEnd;
.....
qryStart = dtmpickFrom.Value;
qryEnd = dtmpickTo.Value;

var query =
from trans in dataSet.Transaction
where ((trans.T_Date >= qryStart)
&& (trans.T_Date <= qryEnd)) ....

I've just done my analysis for January 2009. I have a number of
transactions
with dates of 01/01/2009 then more with later dates. I'm finding that with
qryStart = 01/01/2009 the transactions with that date are being omitted
from
the analysis. Looking at qryStart in the debugger it shows '01/01/09
14:49:52' (where the time reflects the time at which I selected the date
in
the DateTime Picker to do the analysis.) It just so happens that the
transactions with a date of 01/01/09 all have times earlier than 14:49:52
so,
presumably, this explains why they don't appear in the analysis.

I don't actually use the time part of the DateTime variables so is there
any
way I can get the queries to ignore it?
Click to expand...

I think you can chop the time off with a Tostring(format) and still do the
comparison.

var query =
from trans in dataSet.Transaction
where ((trans.T_Date.ToString("yyyyMMdd") >=
qryStart.Tostring("yyyMMdd")
&& (trans.T_Date.ToString("yyyyMMdd" <=
qryEnd.ToString('yyyyMMdd")) ....


I think there is a ToShortDate() which will chop off the time, and you
might be able to get away ToShortDate("yyyyMMdd") too.
 
P

Paolo

eGoran: thank you. That has solvd my problem

Göran Andersson said:
No, you can't, a DateTime value always has a time component. However,
you can set the time component to be zero:

qryStart = dtmpickFrom.Value.Date;
qryEnd = dtmpickTo.Value.Date;

If you want the end date to be inclusive, you should add one day to it:

qryEnd = dtmpickTo.Value.Date.AddDays(1);

In the query you should use the < operator to compare the end date. The
< operator is the exact complement to the >= operator, so that you will
get time ranges where no record will appear in two consecutive ranges.

var query =
from trans in dataSet.Transaction
where ((trans.T_Date >= qryStart)
&& (trans.T_Date < qryEnd)) ....
Click to expand...
 
P

Paolo

Mr Arnold and Ken Foskey: thank you for your suggestions. I have actually
implemented Goran's suggestion but I was also wondering if it was possible to
'chop' off the Time element or at least set it to zero.
 
A

Axel Rietschin

Please, foelks, don't do SILLY stuff like string conversions when all is needed it a little arithmetic...

static DateTime DatePart(DateTime dateTime)
{
return new DateTime(dateTime.Ticks - dateTime.Ticks % 864000000000L);
}

Cheers,
Axel




Paol wrote:

Ignore Time element of DateTime?
01-Feb-09

I have a series of queries which select transactions (using a Transaction
date) within a specified date range, where the start and end dates
(inclusive) are selected from a DateTimePicker control thus

DateTime qryStart
DateTime qryEnd
....
qryStart = dtmpickFrom.Value
qryEnd = dtmpickTo.Value

var query =
from trans in dataSet.Transactio
where ((trans.T_Date >= qryStart
&& (trans.T_Date <= qryEnd)) ...

I've just done my analysis for January 2009. I have a number of transactions
with dates of 01/01/2009 then more with later dates. I'm finding that with
qryStart = 01/01/2009 the transactions with that date are being omitted from
the analysis. Looking at qryStart in the debugger it shows '01/01/09
14:49:52' (where the time reflects the time at which I selected the date in
the DateTime Picker to do the analysis.) It just so happens that the
transactions with a date of 01/01/09 all have times earlier than 14:49:52 so,
presumably, this explains why they don't appear in the analysis

I don't actually use the time part of the DateTime variables so is there any
way I can get the queries to ignore it?

Previous Posts In This Thread:

Ignore Time element of DateTime?
I have a series of queries which select transactions (using a Transaction
date) within a specified date range, where the start and end dates
(inclusive) are selected from a DateTimePicker control thus

DateTime qryStart
DateTime qryEnd
....
qryStart = dtmpickFrom.Value
qryEnd = dtmpickTo.Value

var query =
from trans in dataSet.Transactio
where ((trans.T_Date >= qryStart
&& (trans.T_Date <= qryEnd)) ...

I've just done my analysis for January 2009. I have a number of transactions
with dates of 01/01/2009 then more with later dates. I'm finding that with
qryStart = 01/01/2009 the transactions with that date are being omitted from
the analysis. Looking at qryStart in the debugger it shows '01/01/09
14:49:52' (where the time reflects the time at which I selected the date in
the DateTime Picker to do the analysis.) It just so happens that the
transactions with a date of 01/01/09 all have times earlier than 14:49:52 so,
presumably, this explains why they don't appear in the analysis

I don't actually use the time part of the DateTime variables so is there any
way I can get the queries to ignore it?

Re: Ignore Time element of DateTime?
add 1 day timespan and use < operator.

Re: Ignore Time element of DateTime?
Paolo wrote

No, you can't, a DateTime value always has a time component. However,
you can set the time component to be zero

qryStart = dtmpickFrom.Value.Date
qryEnd = dtmpickTo.Value.Date

If you want the end date to be inclusive, you should add one day to it

qryEnd = dtmpickTo.Value.Date.AddDays(1)

In the query you should use the < operator to compare the end date. The
< operator is the exact complement to the >= operator, so that you will
get time ranges where no record will appear in two consecutive ranges

var query
from trans in dataSet.Transactio
where ((trans.T_Date >= qryStart
&& (trans.T_Date < qryEnd)) ...

--
G??ran Andersso
____
http://www.guffa.com

Re: Ignore Time element of DateTime?

I think you can chop the time off with a Tostring(format) and still do the
comparison.

var query =
from trans in dataSet.Transaction
where ((trans.T_Date.ToString("yyyyMMdd") >=
qryStart.Tostring("yyyMMdd")
&& (trans.T_Date.ToString("yyyyMMdd" <=
qryEnd.ToString('yyyyMMdd")) ....


I think there is a ToShortDate() which will chop off the time, and you
might be able to get away ToShortDate("yyyyMMdd") too.

Re: Ignore Time element of DateTime?
eGoran: thank you. That has solvd my problem

:

Re: Ignore Time element of DateTime?
Mr Arnold and Ken Foskey: thank you for your suggestions. I have actually
implemented Goran's suggestion but I was also wondering if it was possible to
'chop' off the Time element or at least set it to zero.

:


Submitted via EggHeadCafe - Software Developer Portal of Choice
WPF Binding Beyond the Limitation of Name Scopes
http://www.eggheadcafe.com/tutorial...f-49faac8854c8/wpf-binding-beyond-the-li.aspx
 
F

Family Tree Mike

Please, foelks, don't do SILLY stuff like string conversions when all is needed it a little arithmetic...

static DateTime DatePart(DateTime dateTime)
{
return new DateTime(dateTime.Ticks - dateTime.Ticks % 864000000000L);
}

Cheers,
Axel
Click to expand...

The question had to do with ignoring the date part of a dataset in SQL,
not a .Net DateTime.

More efficient to what you suggest would be to use the .Net property
that does what you coded: DateTime.Date. By the way, these both only
truncate the time part of the DateTime. The Time portion is still there
if you write out the object.
 

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