DateTime data type

Stores date, time, seconds, and milliseconds values. 

Properties

The following table illustrates the properties used to define the Data Type:

Scope

Generators: .NET, .NET Framework, Java, Apple, Android

Conversion by DBMS

The following table illustrates the conversion done by GeneXus according to the DBMS:

Static methods

The DateTime data type has two static methods available only for the .NET, .NET Framework, and Java generators.

New

Generates DateTime instances with specific values for date and time.

Syntax

DateTime.New(Year,Month,Day, [Hour],[Minute],[Second],[Millisecond])

Samples

&ExpirationDateTime = DateTime.New(2018,6,5,18,0,0,0)

If &ExpirationDateTime >= DateTime.New(2018,6,5,18,0,0,0)
   msg("The date and time is not allowed")
EndIf

Now

Obtains the current system date and time. 

Syntax

DateTime.Now()

Samples

&datetime = Datetime.Now() 
&dateString = &datetime.ToString()
msg(&dateString) // 09/12/23 12:35 PM

Equivalencies Between Date and DateTime

Assignments
Assignments between Date and DateTime attributes are allowed according to the following rules:

Date = DateTime //The receiving field loses the value corresponding to the time.

DateTime = Date //The receiving field’s time value is 12:00:00 AM (00:00:00 in 24-hour format).

Comparisons
Comparisons between Date and DateTime fields in conditions are not allowed. To compare these two data types, you must convert one into the other using assignments.

For example, if &DT is a DateTime variable and &D is a Date variable, you can use any of the following schemes to compare them.

Scheme 1: Create a temporary DateTime variable and compare

&DT1 = &D  //Converts &D to DateTime and its value remains in &DT1
           //The time part is 12:00.000 AM
if &DT > &DT1
   …
endif

Scheme 2: Create a temporary Date variable and compare

&D1 = &DT    //Converts &DT to Date and its value remains in &D1
             //The time part is lost
if &D > &D1
   …
endif

Parameter Passing
Date and DateTime data types are not equivalent. Programs that expect a Date value cannot be called by programs passing a DateTime value and vice versa; otherwise, an error will occur at specification time.

Indexes and Search
It is possible to create indexes containing DateTime attributes as the only component or as part of the key. They can be ascending or descending (as long as the DBMS allows it).

As far as the search is concerned, consider that it is not possible to search for those that 'have the same date' in a direct way. It will be necessary to implement, for example, the following code:

// Code to search for a DateTime attribute value within a given date.

&dtFrom = ymdhmstot(1995, 10, 28, 0, 0, 0)
&dtTo = ymdhmstot( 1995,10, 29, 0, 0, 0) – 1 // Next day minus 1 second
For each
    Where dtAttribute >= &dtFrom
    Where dtAttribute <= &dtTo
          …
EndFor

Reorganization

The following table discusses the possible data type changes of an attribute during the reorganization process.

N/A. - Not applicable.
Yes. - Conversion is allowed.
No. - Conversion is not allowed. The values are lost.
¹ - Character, Varchar and Long Varchar types.
² - Any numeric data type.
³ - The receiving attribute may be truncated to the right if it is not large enough.
⁴ - The attribute may be truncated to the left if it is not large enough.

Notes

• Changes in the picture of the DateTime attribute do not imply database reorganization. This is because the way the attribute is stored is independent of how it is displayed.
• Changes in precision may imply a database reorganization.
• Empty values are invariable with respect to Precision. Even though the minimum value for a Datetime2 in SQL Server is 0001-01-01, in GeneXus empty and minimum are the same as the one for Datetime: 1753-01-01.

Consideration

When generating iOS code, controls based on the Date / DateTime data type use the Date format property and Hour format property to infer the native styles dateStyle and timeStyle that take into account the user's preferences in the device settings.

See Also

Date data type
Data types list