Examples on Pig Commands | Big Data

In this video, we are going to discuss examples on pick commands

So, at first, we are going to discuss 4-H and generate command

So, the 4-H operator is used to generate specified transformations based on the column data

So, the syntax of 4-H will be like this. So, variable name is equal to 4-H-table-name, generate, and required columns

So, variable name is equal to 4 each table name generate and required columns here

So to execute this command, we need to use the dump comment also

Next one is the filter command. We know that using filter we can see on the specific selected rows or the records

The filter operator is used to select the required tuples from the relation based on a certain

condition. So, the syntax will be like this. So, variable name is equal to filter table name by

the respective conditions. To execute this command, we need to use dump. Next one, we are going for

this order by command The order by operator is used to display the contents of a deletion in a short order based on one or more fields And the syntax of this will be variable name is equal to order table name by field ascending

or descending. So either I shall be using ASC or DESC and then semicolon

The ASC means the ascending order and DESC means that descending order

To execute this command, we need to use dump here. For the better understanding, let us go for one demonstration to show you that how these

commands can work in practice. Now in this video, we shall show you that how to use for each and generate command in our

ground shell. So the first query we are going to execute is that display the name and the city fields for

all rows. So that means I do not want to print name, major and city all the

the three attributes all the three fields I want to display only the name and the city

that means it is it is giving you a flavor of projection where you are selecting

some of the columns but not all the columns but all the rows will be coming

so display the name and the city fields for all rows so at first I shall go for this for gen so there is a variable name you can give some other name also so for gen is equal to for each

student generate city the order in which you are mentioning here in the same

order it will be coming so I shall go for this enter so for each student

generate city common name So now I shall go for say dump to see the content, dump for gen

So we are having five rows. You see all the five rows are coming, but the major is not coming

The department name is not coming. The subject is not coming. There is a major. The city is coming and the name is coming

You see the same command. So it is immaterial, whether you are typing this one all in the capital letters or not

So there is immaterial here. Intentionally I am changing this name the sequence that is the name and the city making this one name and city if I press enter then dump dump for gen so now the name is coming at the front and then cities after that so

names are coming and then the cities are coming for the all rows for the all

five rows now next we shall go for the filter comment so let us consider

one query display the student information where the city is Kolkata so how many how many rows are there with the Kolkata city two rows are

there Amit and Kushal okay so display the student information where the city is

Kolkata so now here I'm going for the selection operation okay so how to do

that one so I shall go for say Cole stood I can give other name also so that

is not an issue so Cole stood is equal to filter I can write this filter in

the capital letters I'm not going to show you that one because I've shown that one earlier in case of forage and generate so by city double equal to within

single code Kolkata you see in the table we're having the Kolkata K capital so

called stute is equal to filter student by city is equal to is equal to Kolkata so

I have executed this one now