How to pick max date for a subject from a sas library along with the dataset name.

[yashraj89]

When there are multiple datasets in a sas library, I want to pick the latest date for that id from all the datasets and to know which particular dataset that date is coming from.

example below
let us assume I have three datasets in library name source like

source.ae, source.cm, source.pr.

In each dataset for id 1 I have date variables. 

I want to club all the dates for the id into 1 dataset and pick the latest date record and know which particular dataset it is coming from. 

Have:

AE data

id    date                    datapagename

1     01/01/2019            AE

CM data

id    date                    datapagename

1     01/02/2019            CM

PR data

id    date                    datapagename

1     01/03/2019            PR

Want :

final dataset:

id     date      datapagename   last date flag

1     01/01/2019     AE

1    01/02/2019     CM

1    01/03/2019     PR                   Y

Thanks

Raj

[Reeza]

How big are these data sets? Is efficiency required? 
If not, just stack them and take the latest record per ID. 

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@yashraj89 wrote:

When there are multiple datasets in a sas library, I want to pick the latest date for that id from all the datasets and to know which particular dataset that date is coming from.

example below
let us assume I have three datasets in library name source like

source.ae, source.cm, source.pr.

In each dataset for id 1 I have date variables. 

I want to club all the dates for the id into 1 dataset and pick the latest date record and know which particular dataset it is coming from. 

Have:

AE data

id    date                    datapagename

1     01/01/2019            AE

CM data

id    date                    datapagename

1     01/02/2019            CM

PR data

id    date                    datapagename

1     01/03/2019            PR

Want :

final dataset:

id     date      datapagename   last date flag

1     01/01/2019     AE

1    01/02/2019     CM

1    01/03/2019     PR                   Y

Thanks

Raj

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Data want;
Length dsn source $50.;
Set ab bc pr Indsname=source;
Dsn=source;
Run;

Proc sort data= want;
By ID descending date; 
Run;

Data flagged;
Set want;
By id;
If first.Id then flag =1;
Run;

Proc sort data = want nodupkey out=max;
By Id;
Run;

[yashraj89]

Below is just an example there are 50 -100 datasets in the library

[Reeza]

---

@yashraj89 wrote:
Below is just an example there are 50 -100 datasets in the library

---

So is your next question how to get a list of all data sets in a library?

If you have a naming convention try some of the options here:

Here is a reference that illustrates how to refer to variables and datasets in a short cut list:
https://blogs.sas.com/content/iml/2018/05/29/6-easy-ways-to-specify-a-list-of-variables-in-sas.html