First. and Last. are fairly well explained in SAS documentation. You may want to search and read it for yourself. In the mean time, here's my quick explanation: When you use BY group processing (statement by customer_key;), SAS creates 2 additionnal automatic variables per by variable to help you process your groups. Assume the following statement: by var1 var2 var3; then SAS creates first.var1 last.var1 first.var2 last.var2 first.var3 last.var3 automatic variables. They are binary (0 or 1) variables that indicate whether the current record is the first (Resp. last) in the current group. Since FALSE=0 and TRUE=1, the statement IF last.customer_key then output; is equivalent logically to IF last.customer_key=TRUE then output; That is, the above statement controls your output and only outputs the last record for each distinct customer_key in query_for_cust_e_0002 to mart.fica_lock_up Imagine the following data set that you read with a BY var1 var2 var3; statement: rownum var1 var2 var3 1 1 1 1 2 1 2 1 3 1 2 2 4 1 2 3 5 1 3 1 In the Above, first.var1 = 1 only for rownum=1. Last.var1=1 only for rownum=5 first.var2=1 for each rownum in (1, 2, 5) and last.var2=1 for each rownum in (1, 4, 5) first.var3=1 for each rownum in (1,2,3,4,5) and last.var3=1 for each rownum in (1,2,3,4,5) Thus, the first and last automatic variables created allow you, for example, to reset counters, reset sums to 0 or products to 1 for your desired by group. They also allow you control over time series where you are only interested in values at the begining and end of a by group, etc. Hope this helps. Vince
... View more
