Creating a join condition - Cloud

Talend Cloud API Services Platform Studio User Guide

author
Talend Documentation Team
EnrichVersion
Cloud
EnrichProdName
Talend Cloud
task
Design and Development
EnrichPlatform
Talend Management Console
Talend Studio

About this task

This step is not obligatory. You can decide to create a business rule without a join condition and use it with only the WHERE clause in the table analysis.

For an example of a table analysis with a simple business rule, see Creating a table analysis with a simple SQL business rule. For an example of a table analysis with a business rule that has a join condition, see Creating a table analysis with an SQL business rule with a join condition.

Procedure

  1. In the SQL business rule editor, click Join Condition to open the corresponding view.
  2. Click the [+] button to add a row in the Join Condition table.
  3. Expand the Metadata folder in the DQ Repository tree view, and then browse to the columns in the tables on which you want to create the join condition.
    This join condition will define the relationship between a table A and a table B using a comparison operator on a specific column in both tables. In this example, the join condition will compare the "name" value in the Person and Person_Ref tables that have a common column called name.
    Note: You must be careful when defining the join clause. In order to get an easy to understand result, it is advisable to make sure that the joined tables do not have duplicate values. For further information, see Creating a table analysis with an SQL business rule with a join condition.
  4. Drop the columns from the DQ Repository tree view to the Join Condition table.
    A dialog box is displayed prompting you to select where to place the column: in TableA or in TableB.
  5. Select a comparison condition operator between the two columns in the tables and save your modifications.
    In the analysis editor, you can now drop this newly created SQL business rule onto a table that has an "age" column. When you run the analysis, the join to the second column is done automatically.
    Warning: The table to which to add the business rule must contain at least one of the columns used in the SQL business rule.