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TOPIC:

(not only empty) datetime literals 07 Apr 2021 15:00 #17972

  • atlopes's Avatar

  • atlopes

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  • Posts: 82
  • Dear All,

    X# 2.7 is not accepting VFP's empty datetime literals and is also interpreting Ante- and Post- Meridian in a different manner.

    In VFP
    ? {^2021-07-04 12:30:00PM}, {^2021-07-04 12:30:00AM}
    * displays: 04/07/2021 12:30:00 04/07/2021 00:30:00

    In X#
    ? {^2021-07-04 12:30:00PM}, {^2021-07-04 12:30:00AM}
    * displays: 04/07/2021 12:30:00 04/07/2021 12:30:00

    Empty date and datetime strings can follow this pattern, after removing all CHR(32):
    {([\/\.-]{0,2})?(T{0,2}:{0,2}((a|A|p|P)(m|M)?)?)?}

    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.

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    Last edit: by robert.

    (not only empty) datetime literals 08 Apr 2021 08:36 #17974

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  • robert


  • Posts: 2118
  • António ,

    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

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    (not only empty) datetime literals 08 Apr 2021 12:25 #17980

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  • atlopes

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  • Posts: 82
  • 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?

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    (not only empty) datetime literals 08 Apr 2021 18:09 #17987

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  • Posts: 19
  • Dear all !

    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

    Hope somebody will help.
    Regards, Andrej

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    (not only empty) datetime literals 08 Apr 2021 18:27 #17988

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  • robert


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  • Andrej,

    wrote: myDate := {^0001-01-01 00:00:00}


    This is the same as MyDate := DateTime.MinValue

    Robert
    XSharp Development Team
    The Netherlands

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    (not only empty) datetime literals 08 Apr 2021 19:37 #17989

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  • Posts: 19
  • Hi Robert !
    Thanks, good to know .
    Andrej

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