Using Caché System Monitor

You are right, the macro $$$NULL present only in %sqlMigration.inc and this is not the file that developers often include to its project.
I prefer to use the macro $$$NULLOREF/$$$NULLOID from %occExtent.inc, which is available by default in the class that inherits from %Library.Base, and for routines is enough to include %systemInclude.inc.

Why so difficult?
This similarly following condition:

WHERE 
(
year(current_date) - year(DOB)
) >= 13

It Besides above was already indicated, why does not follow to use such a code, for example:

select datediff(year,
todate(to_char({d '1990-12-31'},'YYYY')||':1','YYYY:MM'), -- birthday
todate(to_char({d '2003-01-01'},'YYYY')||':1','YYYY:MM') -- report date
)

This gives an incorrect result - 13, although it should be 12.

The key difference of $classmethod is runtime:

$CLASSMETHOD permits a ObjectScript program to invoke an arbitrary class method in an arbitrary class. Both the class name and the method name may be computed at runtime or supplied as string constants.^proof

Class include is not required (and does not seem to affect anything) and can be omitted

Yeah, I just forgot to delete that line.

Then this:

Include Child

Class Macro.Child Extends Macro.Parent
{

ClassMethod first()
{
  #include Child
}

ClassMethod Test() [ PlaceAfter = first ]
{
  write "Class: " , $classname() , ! , "Value: " , $$$name
}

}

or this:

ClassMethod Test()
{
  #include Child
  write "Class: " , $classname() , ! , "Value: " , $$$name
}

Macro.Parent.cls:

Include Parent

Class Macro.Parent
{

ClassMethod Test()
{
  write "Class: " , $classname() , ! , "Value: " , $$$name 
}

}

Macro.Child.cls:

Include Child

Class Macro.Child Extends Macro.Parent
{

ClassMethod Test()
{
  write "Class: " , $classname() , ! , "Value: " , $$$name 
}

}

Parent.inc:

#ifndef name
  #define name "Parent"
#endif name

Child.inc:

#define name "Child"

Result:

>do ##class(Macro.Parent).Test()
Class: Macro.Parent
Value: Parent
>do ##class(Macro.Child).Test()
Class: Macro.Child
Value: Child

This data is saved in the registry. You can even save greater value than allowed by the program (see screenshot).

Example of work with the registry directly from Caché Object Script can be found here.

For better performance you should make a few changes:

1. add an index on DOB field
2. rebuild the index and run TuneTable
3. modify the query
   

   select DOB from HSAA.Patient
   where
   dob<=dateadd('yy',-13,current_date)
   or dob between
         todate((year(current_date)-13)||'0101','yyyymmdd')
     and todate((year(current_date)-13)||'1231','yyyymmdd')

The result will pleasantly surprise you.

Hi Marco.

CSVTOCLASS creates a new class if it doesn't already exist and then it calls the Import method.

Since you already have created the class, it is not created, but there is no Import method, so nothing works.

Solution:

1. delete all previously created classes: ZenImport.Country, TestCsv.Csv, etc.
2. run in terminal:
   

   USER>set rowtype = "Code VARCHAR(2),Name VARCHAR(9)"
   USER>set filename = "c:\temp\Country.csv"
   USER>do ##class(%SQL.Util.Procedures).CSVTOCLASS(2, .rowtype, filename,";",,,"Test.CSV")
   

3. run in Portal:
   

   select * from Test.CSV

   open and see the class "Test.CSV". Profit!!!

Never use DATEDIFF for accurate calculation of the age since days and months here are not taken into account.

See example

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

The default ciphersuite string has changed to include new options and is now: ALL:!aNULL:!eNULL:!EXP:!SSLv2

So the documentation is outdated?

The default for a Caché configuration is TLSv1:SSLv3:!ADH:!LOW:!EXP:@STRENGTH which breaks down into the following group of colon-separated statements:
<...>

Finding Values in Globals

Look features Caché Monitor.