1.
The following SAS program is submitted:
data work.retail;
cost = '20000';
total = .10 * cost;
run;
Which one of the following is the value of the variable TOTAL in the output data
set?
A. 2000
B. '2000'
C. . (missing numeric value)
D. ' ' (missing character value)

答案为A，理由是SAS automaticly converted the character value cost to numeric 20000.

但是另一道题：
30.The descriptor and data portions of the Work.Salaries data set are shown below.
Variable Type Len Pos
name   Char  8     0
salary   Char  8    16
status  Char  8     8

name    status salary
Liz         S       15,600
Herman S       26,700
Marty    S       35,000

The following SAS program is submitted:
proc print data=work.salaries;
where salary<20000;
run;

What is displayed in the SAS log after the program is executed?
a. A NOTE indicating that 1 observation is read.
b. A NOTE indicating that 0 observations were read.
c. A WARNING indicating that character values have been converted to numeric values.
d. An ERROR indicating that the WHERE clause operator requires compatible variables.
答案是D。

我想问为什么第2题SAS没有自动将character转为numeric，而第1题这么做了？

谢谢。