SQL to PROC SQL-Partition Nach Alternative (min Fall)

Question

Ich bin neu in SAS, aber SQL wissen, so versucht, SQL-Code verwenden, proc sql Code schreiben und erkannte, dass PARTITION by ist nicht verfügbar in SAS.

Tabelle

Customer_id Item_type Order Size Date  …. 

1. A401 Fruit   Small  3/14/2016 …. 
2. A401 Fruit   Big  5/22/2016 …. 
3. A401 Vegetable  Small  7/12/2016 …. 
4. B509 Vegetable  Small  3/25/2015 …. 
5. B509 Vegetable  Big  3/15/2014 …. 
6. B509 Vegetable  Small  3/1/2014  …. 

Erklärung

Customer_id Item_Type Count  Reason 
1.A401   Fruit  2   X-WRONG-because date corresponding big item is later than others in group 
2.B509   Vegetable 2   RIGHT-Note that count is 2 only because one of the dates is earlier than the Big corresponding item(3/1/2014 is earlier than 3/15/2014) 

SQL Ausgabe

Customer_id Item_Type Count  
1.B509   Vegetable  2 

select t.customer_id, t.item_type, count(*) 
from (select t.*, 
     min(case when OrderSize = 'Big' then date end) over (partition by customer_id, item_type) as min_big 
    from t 
) t 
where date > min_big 
group by t.customer_id, t.item_type; 

Answer 1

In SQL-Dialekte (MS Access, MySQL, SQLite, SAS proc sql), das zu tun Fensterfunktion nicht unterstützen ns, die meisten PARTITION BY Aufrufe können durch korrelierte Aggregat-Unterabfragen ersetzt werden, die von allen gängigen SQL-Dialekten unterstützt werden. Berücksichtigen Sie die folgende Einstellung:

select main.customer_id, main.item_type, count(*) as count 
from 
    (select t.customer_id, t.item_type, t.date, 
      (select min(case when OrderSize = 'Big' then date end) 
      from t sub 
      where sub.customer_id = t.customer_id 
      and sub.item_type = t.item_type) as min_big 
    from t 
    ) main 
where main.date > main.min_big 
group by main.customer_id, main.item_type;