MS Access 2010 Вопрос по вычислениями с датами

[Cap7]

Надо создать простую таблицу, заезда машин на территорию предприятия, 1-я колонка "везд автомашины" и 2-я колонка "Выезд автомашины" и 3-я колонка "время нахождения на територии" .В колонки должна вносится информация с датой и временем заезда и выезда автомашин и разницу между колонок(3-я колонка) надо получить в часах. Помогите !!!!

[AleksandrH]

Use DateDiff() to calculate the elapsed time. It returns whole numbers only, so if you want hours and fractions of an hour, you must work in minutes. If you want minutes and seconds, you must get the difference in seconds.

Let's assume a date/time field named StartDateTime to record when the employee clocks on, and another named EndDateTime for when the employee clocks off. To calculate the time worked, create a query into this table, and type this into the Field row of the query design grid:

Minutes: DateDiff("n", [StartDateTime], [EndDateTime])

Minutes is the alias for the calculated field; you could use any name you like. You must use "n" for DateDiff() to return minutes: "m" returns months.

To display this value as hours and minutes on your report, use a text box with this Control Source:

=[Minutes] \ 60 & Format([Minutes] Mod 60, "\:00")

This formula uses:

the integer division operator (\) rather than regular division (/), for whole hours only;
the Mod operator to get the left over minutes after dividing by 60;
the Format() function to display the minutes as two digits with a literal colon.

Do not use the formula directly in the query if you wish to sum the time; the value it generates is just a piece of text.

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