您好，数据中Yes=1，No=0，Don't know=-9 .我想生成虚拟变量varname,当CNo12c取1时varname=1，取其他值时varname=0.我试着生成了但是无法识别，是不是需要生成两个虚拟变量，请问有高手帮忙解决吗？多谢！

input byte CNo12c
-9
.
.
.
2
1
.
.
.
.
1
.
.
.
.
.
.
.
.
.
.
2
.
.
2
.
2
2
.
.
2
.
2
.
.
.
1
.
.
.
1
.
.
1
.
.
2
.
.
.
end
label values CNo12c CNO12C
label def CNO12C -9 "Don't know", modify
label def CNO12C 1 "Yes", modify
label def CNO12C 2 "No", modify
[/CODE]
------------------ copy up to and including the previous line ------------------


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