A = LOAD 'student' using PigStorage(',');

by this relation A contains all columns which has student file.You can access these columns by using sequence number like $0,$1,$2
$0 --> First column
$1 --> Second column
$2 --> third column and so on

我可以建议在脚本中使用宏或参数变量，这里的宏就是一个例子

define dividend_analysis (daily, year, daily_symbol, daily_open, daily_close) 
returns analyzed { 
divs = load '/user/data/NYSE_dividends'as (exchange:chararray,     symbol:chararray, date:chararray, dividends:float); 
divisthisyear = filter divs by date matches '.*$year.*';
dailythisyear = filter $daily by date matches '.*$year.*'; 
jnd = join divisthisyear by symbol, dailythisyear by $daily_symbol;
$analyzed = foreach jnd generate $1 ,$daily_close - $daily_open; };

daily = load '/user/data/NYSE_daily'as (exchange:chararray, symbol:chararray,     date:chararray, open:float, high:float, low:float, close:float, volume:int,     adj_close:float); 
results = dividend_analysis(daily, '2009', 'symbol', 'open', 'close');