DateTime data

Date/Time variables are stored internally as a string.

See also the Date / Time Functions section for detailed information concerning date / time input-output formats.

The ph_getvar_XX functions will take these strings and perform the proper data conversion (if possible). This is generally safer and goes a long way into insuring you don’t get syntax errors from data types that dont match. The [LOCALXX] form of a variable is a “search and replace” type of mechanism. If you’re certain that the var contains the datatype that you’re interested in, you can use this form.

Some examples to help make things clear...
if [LOCAL1] contains 5 then...
  [LOCAL1] + 8 >> Returns a number type that equals 13
  [LOCAL1] + “ is a number.” >> Returns a syntax error because the formula actually passed to the evaluator will look like: 5 + “ is a number.”
  “[LOCAL1]” + “ is a number.” >> Returns a string that looks like: 5 is a number.
  “[LOCAL1] is a number.” >> Also works and is the equivalent of the formula just above.

Using this background, if the [LOCAL3] var contains a saved datetime value in the form of 12/15/2010 10:49:00 it will fail in this formula: ph_minutesafter([LOCAL3],today())

But...it will suceed if the saved datetime value in [LOCAL3] looks like: 2010-12-15 10:49:00, or the formula was changed to ph_minutesafter(ph_getvar_dt(1,3),today())

To create a negative time value (before an event) use this form . . . “ph_relativetime ( 00:00:00,[SUNRISE]-15*60)“ which would be 15 minutes before SUNRISE.

You can specify a literal date, time, or datetime by using the format of "yyyy-mm-dd hh:mm:ss.ttt"  That is with dashes, not slashes between date items and no comma between the date and time.

   [NOTE: the date is year-month-day ordered.]

For example the formula...

     ph_relativedatetime(2013-12-01 13:38:15.306,90)

Will give you back a datetime that is 90 minutes later than the entered datetime... almost. The milliseconds portion will always be 0, as the ph_relativedatetime function truncates time to seconds. If you want millisecond precision, you must use the ph_relativedtprecise function.

If you are wondering why the function today() returns its output in mm/dd/yyyy hh:mm:ss format rather than the literal datetime input, it is due to Windows formatting of datetime values which are controlled by regional settings. So input is always yyyy-mm-dd hh:mm:ss.fff and output can vary (usually mm/dd/yyyy hh:mm:ss in the United States) based upon Windows regional settings.

To better understand how to create formulas with Date/Time & System values the following chart demonstrates how various functions resolve their output values...

Formula	Result
ph_secondsafter(06:30:00, 06:32:00)	120
[SUNRISE]	22869
ph_relativetime(00:00:00,[SUNRISE])	06:25:26
ph_relativetime(00:00:00,[SUNRISE]-60)	06:24:26
ph_relativetime(00:01:00,[SUNRISE])	06:26:26
ph_relativetime(02:00:00,90)	02:01:30
Now()	14:57:22:463
ph_relativetime(now(),30)	14:57:52
Today()	12/01/2013 14:57:22
ph_relativedatetime(today(),30)	12/01/2013 14:57:52
ph_relativedatetime(datetime("09/23/13 12:00:00"),30)	09/23/2013 12:30:00
ph_relativedatetime(2013-09-23 12:00:00,30)	09/23/2013 12:30:00
datetime("09-23-13 08:15:00")	09/23/2013 08:15:00
time("06:30:00")	06:30:00
Now()>07:00:00	True if after 7AM
datetime(today(),08:00:00)	12/01/2013 08:00:00