使用SUM时出现猪脚本错误（）

Question

运行此PIG脚本时出现以下错误....请帮助!!! 在此先感谢。

"ERROR 1000: Error during parsing. Scalars can be only used with projections" 

MOVIES = LOAD '/MOVIES' using PigStorage(',') as (mid:double, mn:chararray, yr:int, rt:float, dr:int); 

Filter11 = filter MOVIES by $2 >= 1950; 

Filter12 = filter Filter11 by $2 <= 1960; 

Group1 = group Filter12 by yr; 

Count1 = foreach Group1 generate group, COUNT(Filter12); 

Sum1 = foreach Count1 generate SUM(Group1); 

DUMP Sum1; 

Answer 1

结合两个过滤条件，并在最后一步计数COUNT（Filter11）或$ 1。

MOVIES = LOAD '/MOVIES' using PigStorage(',') as (mid:double, mn:chararray, yr:int, rt:float, dr:int); 
Filter11 = filter MOVIES by ($2 >= 1950 and $2 <= 1960); 
Group1 = group Filter11 by yr; 
Count1 = foreach Group1 generate group, COUNT(Filter11); 
Sum1 = foreach Count1 generate SUM($1); 
DUMP Sum1;