How does one save and retrieve date values from sql server ce in c++?

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How does one save and retrieve date values from sql server ce in c++?

Ok.I have to get date from month_cal control in form of a SYSTEMTIME structure and save into sqlserver ce database.How do I do this.
I thought of adding a parameter like shown below but don't know how to construct the variant value.Since it a date parameter I am creating, does adding a string in the formate dd/mm/yyyy make sense?
Also, I need to get saved date from data base and use it to update a monthcal control using systen time.How do I retrive the date value considering that c++ has no date data type(I know sql server does)

Relevant input code fragment is:
Cmd->Parameters->Append(Cmd->CreateParameter(_bstr_t(_T("Name")),adDate,adParamInput, -1, _variant_t(SOME_VALUE_WHOSE_C++_TYPE_IS_UNKNOWN_TO_ME)));

Relevant output code fragment is:
SOME_UNKNOWN_C++_TYPE_TO_ME Result = (SOME_UNKNOWN_C++_TYPE_TO_ME)Rs->Feilds->Item[0]->Value;

Posted 22-Mar-14 1:24am

Gbenbam

Updated 22-Mar-14 1:33am

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Richard MacCutchan · Accepted Answer · 2014-03-22T01:52:00

Solution 1

You should always use DateTime types in your database. Never use strings for storing dates, as it creates more problems than it solves. You can use the COleDateTime Class[^] in C++.

Posted 22-Mar-14 1:52am

Richard MacCutchan

Comments

Gbenbam 22-Mar-14 8:06am

Thanks a lot.But please can the COleDateTime be used in a WIN32 c++ project type too.Or is it restricted to only MFC prohects.

Richard MacCutchan 22-Mar-14 8:59am

It is a shared class and can be used via the Active Template Library.

Jochen Arndt · Accepted Answer · 2014-03-22T01:54:00

Solution 2

The _variant_t class has a date member. Because dates are stored as double values, you must use a datetime type that uses the same encoding like COleDateTime and DATE. Then you can assigne the date value:

SYSTEMTIME st;
COleDateTime odt(st);
_variant_t vt;
vt.vt = VT_DATE;
vt.date = odt;

DATE dt;
::SystemTimeToVariantTime(&st, &dt);
vt.vt = VT_DATE;
vt.date = dt;

Posted 22-Mar-14 1:54am

Jochen Arndt

Comments

Gbenbam 22-Mar-14 8:12am

Thanks a lot.These your code snippets address only am attempt to save date into a database.Could you kindly help with matching code snippets for retrieving date type from a variant that was holds a date type I.e one with vt = VT_DATE.

Does a VariantTypeToSystemTime function exist?

Jochen Arndt 22-Mar-14 8:17am

Just check for the DATE type and use the value:
if (VT_DATE == vt.vt)
VariantTimeToSystemTime(vt.date, &st);