PATCH A SharePoint Date & Time Column In Power Apps

Goal

Change the VacationStartDateTime column (Date & Time Type) from blank to 12/25/2020 9:30AM.

Input

Vacation Requests (SharePoint List)

ID	EmployeeName	VacationStartDateTime	Hours
1	Matthew Devaney		8

Patch Function Code

Patch(
    'Vacation Requests',
    LookUp('Vacation Requests', ID=1),
    {
        VacationStartDateTime: Date(2020,12,25) + Time(9,30,0)
    }
)

Output

Vacation Requests (SharePoint List)

ID	EmployeeName	VacationStartDateTime	Hours
1	Matthew Devaney	12/25/2020 9:30AM	8

Scenario #1: Date & Time Picker

Patch a value found in a date & time picker to a Date & Time field.

Patch Function Code

Patch(
    'Vacation Requests',
    LookUp('Vacation Requests', ID=1),
    {
        VacationStartDateTime: 
            DatePicker_VacationDate.SelectedDate
            + Time(
                Value(Dropdown_Hours.Selected.Value),
                Value(Dropdown_Minutes.Selected.Value),
                0
            )
    }
)