在SAS Ent Guide中减去行数

Question

我有以下数据集：

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    

我是否可以在查询构建器中为每个客户从第2行中减去第1行中的条件，这样我就可以获得“天数”，之后客户续订其会员资格？
基本上，我需要帮助减去查询构建器中的行 请adivse。

Answer 1

如果你写一个datastep，这不是太难。我不知道它在Query Builder中很容易完成。

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;