'Present perfect' and 'today'

[marlipp]

Hello everybody,

put the case that my son has finished his first day at school and in the evening I want to express this. Which sentence would be correct:

My son joined school today.
Or
My son has joined school today.

Is it possible to use the present perfect with 'today'?

thanks
marlipp

[Marius Hancu]

Yes:
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Proceedings‎ - Page 70 (http://books.google.com/books?id=bVwMAQAAIAAJ&q=%22has+completed++*++today%22&dq=%22has+completed++*++today%22&lr=)

by National Guard Association of the United States - 1963

The other announcement I have is that the Air National Guard has completed another deployment today with its customary measure of success.
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Hearings: Public works‎ - Page 1551 (http://books.google.com/books?id=GVZcYrccjSwC&q=%22has+completed++*++today%22&dq=%22has+completed++*++today%22&lr=)

by United States. Congress. House. Committee on Appropriations - Biography & Autobiography (http://books.google.com/books?q=+subject:%22Biography+%26+Autobiography%22&lr=) - 1959

It said : Congress has just completed action today on a .$25 million flood relief measure and President Truman has gotten more Federal help underway in the
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Blackrobe‎ - Page 97 (http://books.google.com/books?id=CtN-mMvu6kMC&q=%22has+completed++*++today%22&dq=%22has+completed++*++today%22&lr=)

by Robert Emmet Wall - Fiction (http://books.google.com/books?q=+subject:%22Fiction%22&lr=) - 1981 - 359 pages

Oudry held the panel so that everyone could see it. "Her Majesty has just
completed this today," he said. All at the table applauded politely and the
Queen ...
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Review of arms control implications of the report of the President's ...‎ - Page 190 (http://books.google.com/books?id=Ji01AAAAIAAJ&q=%22he+has+joined++*++today%22&dq=%22he+has+joined++*++today%22&lr=)

by United States. Congress. House. Committee on Foreign Affairs - Strategic forces (http://books.google.com/books?q=+subject:%22Strategic+forces%22&lr=) - 1983 - 225 pages

We are honored he has joined us today. General Scowcroft.

General SCOWCROFT.
Thank you very much. I won't pretend to describe what the Commission did in ...
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as the facts are presented as being relevant to the present situation and recent enough.

In your case, I'd say:

My son joined school earlier today. [the separation with the past is more clear
My son has just joined school today. [just makes the event more recent, better for present perfect

Now, in:

We are honored he has joined us today. General Scowcroft.

it is clear that the general is still with the committee, present there, thus his "joining" is relevant to the present moment at that time, and the perfect present is correctly used.