How to Subtract or Add dates

Question

Question

Thembelani Mlalazi · Dec 5, 2017

I am trying to age based on a given date and current date here is my code:


Property DOB As %Date
Method GetAge() As %Integer
{
   if (..DOB="")
    {
  set today=0 
    }
   else
  {
  set today=$ZDate($HOROLOG,2)-$ZDate(..DOB)
  }
  write "Today's==="_$ZDate($HOROLOG),!
  write today
  return today
}

Discussion (4)1

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Vitaliy Serdtsev · Dec 5, 2017

See Sample.Person in "SAMPLES".

/// Person's age.<br>
/// This is a calculated field whose value is derived from <property>DOB</property>.
Property Age As %Integer [ Calculated, SqlComputeCode = { Set {Age}=##class(Sample.Person).CurrentAge({DOB})}, SqlComputed, SqlComputeOnChange = DOB ];

/// This class method calculates a current age given a date of birth <var>date</var>.
ClassMethod CurrentAge(date As %Date = "") As %Integer [ CodeMode = expression ]
{
$Select(date="":"",1:($ZD($H,8)-$ZD(date,8)\10000))
}

4 0

score 0 · Answer 1 · 2017-12-05T04:32:02-05:00

Dmitry Maslennikov · Dec 5, 2017

you can use function DATEDIFF from SQL

write $system.SQL.DATEDIFF("yy", $zdh("01.01.1990",4), $h)

0 0

score 0 · Answer 2 · 2017-12-05T05:05:35-05:00

In this case $system.SQL.DATEDIFF is not suitable:

USER>w $system.SQL.DATEDIFF("yy", $zdh("30.12.1990",4), $zdh("01.01.1991",4))
1

USER>w ($ZD($zdh("01.01.1991",4),8)-$ZD($zdh("30.12.1990",4),8))\10000
0

score 2 · Answer 3 · 2017-12-08T06:28:39-05:00

I won't embarrass myself by listing the MUMPS code from 1991 that does this on our application, but I will comment that you need to work out how many birthdays have gone by so it must compare month and day values once the basic year subtraction has been done. It gets quite complicated. (Might also like to look at whether you need more than just a "years old", and also need months or days for very low values.)

Mike