減去行

Question

，我有以下數據集：

Row - Customer - Renew Date  - Type of Renewal  - Days 
1  - A  - June 10, 2010  - X       
2  - A  - May 01, 2011   - Y 
3  - B  - Jan 05, 2010   - Y 
4  - B  - Dec 10, 2010   - Z 
5  - B  - Dec 10, 2011   - X  

有沒有一種方法，我可以把查詢生成器的條件在那裏減去第1行第2行的每一位客戶，讓我可以有客戶續訂其會員資格後的「天數」？
基本上，我需要幫助減去查詢生成器中的行。
請adivse。

Answer 1

如果你寫一個datastep，這並不難。我不知道這很容易在Query Builder中完成。

data have; 
informat renew_date ANYDTDTE.; 
format renew_date DATE9.; 
infile datalines dlm='-'; 
input Row Customer $ Renew_Date Renewal_Type $; 
datalines; 
1  - A  - June 10, 2010  - X       
2  - A  - May 01, 2011   - Y 
3  - B  - Jan 05, 2010   - Y 
4  - B  - Dec 10, 2010   - Z 
5  - B  - Dec 10, 2011   - X  
;;;; 
run; 

data want; 
set have; 
by customer; 
retain prev_days; *retain the value of prev_days from one row to the next; 
if first.customer then days_since=0; *initialize days_since to zero for each customer's first record; 
else days_since=renew_date-prev_days; *otherwise set it to the difference; 
output; *output the current record; 
prev_days=renew_date; *now change prev_days to the renewal date so the next record has it; 
run;