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标题: 关于SQL中Count的使用 [打印本页]

作者: shiyiming 时间: 2006-6-9 12:13
标题: 关于SQL中Count的使用
data a;
input a b;
cards;
1 1
2 1
1 1
1 2
2 2
. 2
. 2
1 .
2 .
. .
. .
;
run;
proc sql;
select count(*) as countall,count(a) as count1, count(distinct a) as count2,b
from a
group by b;
quit; 从输出结果中可以清楚count对缺失值是怎么处理的。

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