Your date-time compendium.

YOUR DATE/TIME COMPENDIUM Have you ever wished that a monthly performance report could compute the number of days in the month to which it pertains? Have you ever wanted to date-stamp a spreadsheet with the last day of the current month instead of today's date? Have you ever used the formula @MONTH(@TODAY)-1, only to have the formula return 0 in January?

I the answer to any of these questions is yes, read on. You'll find the solutions to these problems, plus eight other techniques that use 1-2-3's and Symphony's powerful date and time arithmetic capabilities. But first remember that for Lotus date and time functions to work properly, your computer must know the correct date and time. If you're lucky enough to have a clock card installed in your computer, chances are the system time and date automatically update when you turn the computer on. Otherwise, you should enter the time and date manually at the DOS level before beginning your 1-2-3 or Symphony session.

To do so, enter the DOS command DATE at the DOS prompt. The date currently stored in the computer will appear, and you'll be prompted to enter a new date. If the system date is today's date, press Return. If the system date is incorrect, enter today's date in the form MM-DD-YY--for example, 4-16-87.

Next enter the command TIME. Again, the current system time will appear, followed by a prompt for a new time. Enter the current time in the format HH:MM or HH:MM:SS. Be sure to use 24-hour time--for example, enter 1 P.M. as 13:00.

If you happen to include the TIME and DATE commands in an AUTOEXEC.BAT file, you'll automatically be prompted for the time and date every time you turn your computer on. (For more on AUTOEXEC.BAT files, see "Exploiting the Power of DOS" in the June 1985 issue.)

Once you've apprised your computer of the correct time and date, start 1-2-3 or Symphony and test these techniques. (You may want to set your system-clock date to April 16, 1987, since the formulas and techniques described in this article assume that is the current date.)

FORMATS FOR DATE AND TIME

All releases of 1-2-3 and Symphony offer various date and time formats. In column A of a blank worksheet, enter the formula @DATE(87,4,16). The 5-digit serial date number 31883 appears in the cell. This number represents April 16, 1987. To give this value a date format, press slash, select Range Format Date 2 (in Symphony press …