https://www.tutorialspoint.com/apache_pig/apache_pig_foreach_operator.htm

Given below is the syntax of FOREACH operator.

grunt> Relation_name2 = FOREACH Relatin_name1 GENERATE (required data);

Example

Assume that we have a file named student_details.txt in the HDFS directory /pig_data/ as shown below.

student_details.txt

001,Rajiv,Reddy,21,9848022337,Hyderabad

002,siddarth,Battacharya,22,9848022338,Kolkata

003,Rajesh,Khanna,22,9848022339,Delhi

004,Preethi,Agarwal,21,9848022330,Pune

005,Trupthi,Mohanthy,23,9848022336,Bhuwaneshwar

006,Archana,Mishra,23,9848022335,Chennai

007,Komal,Nayak,24,9848022334,trivendram

008,Bharathi,Nambiayar,24,9848022333,Chennai

And we have loaded this file into Pig with the relation name student_details as shown below.

grunt> student_details = LOAD 'hdfs://localhost:9000/pig_data/student_details.txt' USING PigStorage(',')

as (id:int, firstname:chararray, lastname:chararray,age:int, phone:chararray, city:chararray);

Let us now get the id, age, and city values of each student from the relation student_details and store it into another relation named foreach_data using the foreach operator as shown below.

grunt> foreach_data = FOREACH student_details GENERATE id,age,city;