Hi David, 

The link for the IRIS Community Edition AWS listing has changed (it won't again). I would suggest editing this post to update it. 

https://aws.amazon.com/marketplace/pp/B07MSHYLF1

Thanks,

Joe

We want our code to be as accessible and readable as possible to as many people as possible. We always prefer whitespace formatting and curly brackets to arcane one line syntax. Someone who's not an Object Script expert will know what this does -

if a { 
   set b=a 
}

But there's no guarantee that a novice will necessarily know what these do -

if a set b=a

set:a b=a

Good code is readable and clever one liners will get in the way of that goal.

The %vid is something that you're going to need to specifically select even when using *. This is documented here - but it seems that this is the documentation you're quoting already :)

http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY…

I'm a little confused about what you mean when you say,

"He is confused that select %vid from (select ...) returns dummy number whilst select *,%vid from (select...) returns correct data."

Running this query might help clarify,

select Id, name, %vid From (select top 10 * from Sample.Person order by name) where %vid BETWEEN 5 and 10

The %vid is not a dummy number - in this case it is essentially to the row ID of the result that we're selecting from. In this case, it represents the integer ranking of the records alphabetized by name, but it really depends on the query. This is not the ID of the person records themselves.  

You don't necessarily need to do a "select *,%vid...", but most likely you want to select some other columns from the view besides %vid.

Does this help?

Thanks Kyle!

Just for clarity, here's a little more context regarding the Identity keyword and the IdKey keyword. Specifically, regarding what other effects these might have on your table/class design.

Identity 

• Like the Highlander, there can only be one property marked [Identity], otherwise you will get a compile error. This is pretty intuitive, but the reason for this is that the property is being mapped to an "identity column" (really, SQL IDENTITY) in the SQL table. 
• Identity properties MUST be of type %Integer. 

IdKey

• This keyword specifies that the property(ies) that we're using to build this index  will be combined to form the "Object Identity" value for the instance of the object in question.
  • The "Object Identity" value is what use to locate and uniquely identify persistent objects.
  • As a result, if there is an IdKey index built using certain properties, you CANNOT modify the values of those properties after you have saved the object (or inserted the row).
• "IdKey" indexes are "Unique". That is, it is redundant (but allowed) to have an index tagged as both Unique and IdKey
• It is not recommended to have "||" (sequential double pipes) in the properties that are used to build the IdKey index. This will result in unpredictable behavior. 
  • This is an artifact of how Caché SQL engine works.
  • The exception, of course, is if that property is a valid reference to a persistent class.