参考其他表以检查日期范围内的记录

Question

I am working a with a series of transactions and inventory receipt. My goal is to create a flag to see whether at up to 5 days before the of the transaction whether the company received a shipment of goods for that item. The pseudo logic is as follows:

For each transaction date: 
   For all inventory receipts whether inventory.item# = transaction.item#
       Are there records between transaction date - 5 and transaction date?

Normally, I would just create two tables and join them, but they really are two separate data structures.My initial attempt:

PROC SQL;
   Create Table TABLE 1 AS 
         SELECT TRANSACTION.DATE, 
                SUM(CASE WHEN INVENTORY.DATE BETWEEN (TRANSACTION.DATE - 5 AND TRANSACTION.DATE) AND INVENTORY.ITEM = TRANSACTION.ITEM;

But how would I reference the tables? I'm not sure left/right/inner joins are appropriate here. I'm not really trying to join the tables, am I?

EDIT: My data is structured is as follows:

TRANSACTION TABLE 

ITEM DATE
0012 12/2
0231 12/3
0421 12/3 

INVENTORY TABLE 

0012 11/30
0231 12/4
0421 12/1

For ITEM 0012, we would look at the inventory table and see that there was a receipt on 11/30 for that item, so that would be flag = 1. For item 0231, we see that there was no inventory recipe within five days of the transaction, so flag = 0.

Answer 1

A standard SQL query works here for me, not sure why you felt a standard join wouldn't work. Given the structure you've laid out, it works, and with your sample data. If you have duplicates for dates and items I'm not sure how it would work, but you didn't include that in your question and I have to assume that your sample data is reflective of your actual situation.

Assuming, Table names are t1 and t2:

proc sql;
create table want as
select t1.*, t2.date as date2, 
    case when not missing(t2.date)  then 1 
            else 0 
     end as check_flag
from t1 as t1
left join t2 as t2
    on t1.item=t2.item
    and t2.date between t1.date-5 and t1.date;
quit;