The simultaneous capture of the Group 1 and Group 2 (that is, the date part and the time part) will result in an empty datetime. All other matches will result in an empty date literal.
Thanks for the suggestions. So 12:30 AM is not interpreted correctly. I must say that I find the US notation VERY confusing (why is that not 00:30:00 AM ?).
An empty DateTime will be difficult. We wiil have to convert these to either a DateTime.MinValue or an uninitialized Nullable Datetime .
Robert
XSharp Development Team
The Netherlands
robert@xsharp.eu
I agree with you, Robert; it's confusing. In a 12-hour notation system, we shouldn't be allowed to use the 12th hour, in the same way that we can't use the 24th hour in a 24-hour notation system.
Another question regarding the datetime literals I forgot to mention: VFP follows the ISO-8601 pattern to indicate a time part that may be preceded by a T. So, {^2021-04-08T11:19:00} should not trigger a compile error.
As for the "empty" datetimes, I understand that it may pose a problem. I would prefer an uninitialized Nullable, but that's just me. How is X# addressing empty dates and datetimes in dbf tables?
If we agree that sometimes we need empty values for a dates, than in a real world this fact can be very painfull.
In my case I got a problems with null dates in my SQL tables. My development environment is now .NET, X# Core dialect.
For a various purposes I am reading a data and saving them in a List structure.
There were no errors at compile time, but at a run time programme crashes. I found that a problem were empty values in some types of fields. I spent some hours solving empty (null) dates.
Here is my solution: (DatiTime literals)
....
Method XS_LoadDataFromMSSQL(sConnStr AS STRING) as void
LOCAL oConn AS System.Data.SqlClient.SqlConnection
LOCAL oCommand := NULL AS System.Data.SqlClient.SqlCommand
LOCAL myDate AS DateTime
LOCAL oDT := DataTable{"MySQLTable"} as DataTable
LOCAL oData := List<SQL_Data>{} as List<SQL_Data>
oConn := OpenConnection(sConnStr)
TRY
oCommand := oConn:CreateCommand()
oCommand:CommandText := "Select PRICE,PRICE_DATE from MySQLTable"
oConn:Open()
¸ self:oDT := DataTable{"MySQLTable"}
foreach row as DataRow in self:oDT:Rows
// testing null values (empty dates)
if row["PRICE_DATE"] == DBNull.Value
// it works --> set value 01.01.0001
// myDate := default(DateTime)
// or put X# DateTime Literals
myDate := {^0001-01-01 00:00:00}
else
myDate := Convert.ToDateTime(row["PRICE_DATE"])
endif
oData:Add(SQL_Data{} Price := Convert.ToDouble(row["PRICE"]),PriceDate := myDate })
next
robert wrote:An empty DateTime will be difficult. We wiil have to convert these to either a DateTime.MinValue or an uninitialized Nullable Datetime .
Hi Robert,
problem might be compounded be previous upsize efforts: ^1899.12.31 is/was often inserted via ODBC or OleDB into the C/S datastore. Some opted to update values with .null. in advance of upsizing, others felt the need to differentiate between BLANK (=MinValue) and .null.
Perhaps not hardcoding, but offering x# conversion functions to overwrite on app level depending on backend and other necessities (but defaulting to DateTime.MinValue) is better, as it allows explicit intent or backend-specific MinValues to be followed.
edit:
at
