Scenario: Mapping data using a subquery - 6.3

Talend Open Studio for Big Data Components Reference Guide

EnrichVersion
6.3
EnrichProdName
Talend Open Studio for Big Data
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

This scenario describes a Job that maps the data from two input tables PreferredSubject and CourseScore to the output table TotalScoreOfPreferredSubject using a subquery.

The PreferredSubject table contains the student's preferred subject data. To reproduce this scenario, you can load the data to the table from a CSV file like the following. For how to load data to a Teradata table, see Scenario: Loading data into a Teradata database.

SeqID;StuName;Subject;Detail
1;Amanda;art;Amanda prefers art.
2;Ford;science;Ford prefers science.
3;Kate;art;Kate prefers art.

The CourseScore table contains the student's subject score data. To reproduce this scenario, you can load the data to the table from a CSV file like the following. For how to load data to a Teradata table, see Scenario: Loading data into a Teradata database.

SeqID;StuName;Subject;Course;Score;Detail
1;Amanda;science;math;85;science score
2;Amanda;science;physics;75;science score
3;Amanda;science;chemistry;80;science score
4;Amanda;art;chinese;85;art score
5;Amanda;art;history;95;art score
6;Amanda;art;geography;80;art score
7;Ford;science;math;95;science score
8;Ford;science;physics;85;science score
9;Ford;science;chemistry;80;science score
10;Ford;art;chinese;75;art score
11;Ford;art;history;80;art score
12;Ford;art;geography;85;art score
13;Kate;science;math;65;science score
14;Kate;science;physics;75;science score
15;Kate;science;chemistry;80;science score
16;Kate;art;chinese;85;art score
17;Kate;art;history;80;art score
18;Kate;art;geography;95;art score

Before the Job execution, there is no data in the output table TotalScoreOfPreferredSubject:

SeqID;StuName;PreferredSubject;TotalScore

Dropping and renaming the components

  1. Create a new Job and add the following components by typing their names in the design workspace or dropping them from the Palette: two tELTTeradataInput components, two tELTTeradataMap components, and one tELTTeradataOutput component.

  2. Rename two tELTTeradataInput components to PreferredSubject and CourseScore respectively, two tELTTeradataMap components to ELTSubqueryMap and ELTMap respectively, and the tELTTeradataOutput component to TotalScoreOfPreferredSubject.

Configuring the input components

  1. Double-click PreferredSubject to open its Basic settings view.

  2. In the Default Table Name field, enter an input table name. In this example, it is PreferredSubject.

  3. Click the [...] button next to Edit schema to define the schema of the input table PreferredSubject in the schema editor.

    Click the [+] button to add four columns, SeqID with the DB Type set to INTEGER, StuName, Subject, and Detail with the DB Type set to VARCHAR.

    Click OK to validate these changes and close the schema editor.

  4. Connect PreferredSubject to ELTMap using the Link > PreferredSubject (Table) link.

  5. Double-click CourseScore to open its Basic settings view.

  6. In the Default Table Name field, enter an input table name. In this example, it is CourseScore.

  7. Click the [...] button next to Edit schema to define the schema of the input table CourseScore in the schema editor.

    Click the [+] button to add six columns, SeqID and Score with the DB Type set to INTEGER, StuName, Subject, Course and Detail with the DB Type set to VARCHAR.

    Click OK to validate these changes and close the schema editor.

  8. Connect CourseScore to ELTSubqueryMap using the Link > CourseScore (Table) link.

Configuring the output component

  1. Double-click TotalScoreOfPreferredSubject to open its Basic settings view.

  2. In the Default Table Name field, enter an output table name. In this example, it is TotalScoreOfPreferredSubject.

  3. Click the [...] button next to Edit schema to define the schema of the output table in the schema editor.