WebFOCUS Online Help > Creating Reports With Report Assistant > Working With Data and Data Sources > Working With Joins

Working With Joins

How to:

A join is a temporary connection between two or more data sources that share at least one common field. Once you join two data sources, each time WebFOCUS retrieves a record from the first data source (host file), it also retrieves the matching records from the second data source (target file).

You use the Join tool to link data sources in both Report Assistant and Graph Assistant. The Join tool provides a graphical method for creating and manipulating joins. You can also create define-based joins and multi-field joins.

When you access the Join tool, the window displays a field list for the host data source (which you specified when you created the Standard Report or Reporting Object), and a field list for any target data source you add to the window.

Important:

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Procedure: How to Create a Join
  1. Click the Join options tab in Report Assistant or Graph Assistant and click New.

    The WebFOCUS masters list dialog box opens where you select a target data source.

  2. Select a data source and click OK.

    The following image shows the Join settings window where you select fields from the Host field and the Target field lists to create a join.

  3. Select the fields you want to join from the Host field list and the Target field list and add them to their respective Selected Fields boxes.

    or

    Press Alt+M to go to the Host field list.

    or

    Press Alt+T to go to the Target field list.

    Then, tab to the field and press Enter to add the chosen field to the corresponding Selected Fields box.

    Note: Fields must have the same format and be indexed fields in order to use them to create joins.

  4. Select your join properties:
    • Unspecified. This option is selected in the Join properties when a join that was created in a release earlier than Version 7, Release 1 is opened in the Join tool. In versions prior to Version 7 Release 1, the defaults for join type and other operators were assumed and not specified in the generated code. Since the Join tool cannot determine the type of join that was created and if there were other commands set to control the join, select the appropriate options (Inner Join, Left Outer Join, Multiple Instances, Single Instances) from the Join tool to upgrade the generated code.
    • Inner Join. A join that results when a report includes host rows that have corresponding cross-referenced rows.
    • Left Outer Join. Extends the results of an Inner Join and retrieves records from both host and cross-referenced tables, including all records from the left table (host) and any records from the right table (cross-referenced) where the condition values match. If there are no matching values in the cross-referenced table, the join still retrieves records from the host table.
    • Multiple Instance (formerly Non Unique). A one-to-many join structure that matches one value in the host data source to multiple values in the cross-referenced field. Joining employee ID in a company's employee data source to employee ID in a data source that lists all the training classes offered by that company would result in a listing of all courses taken by each employee, or a joining of the one instance of each ID in the host file to the multiple instances of that ID in the cross-referenced file. The default join type is inner.
    • Single Instance (formerly Unique). A one-to-one join structure that matches one value in the host data source to one value in the cross-referenced data source. Joining an employee ID in an employee data source to an employee ID in a salary data source is an example of a unique join.
  5. To see the join syntax, click View.
  6. Click OK.
  7. In the Description box, give the join a meaningful and unique name.
  8. Click Save & Create and the new join appears in the Joins list.
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Procedure: How to Create a Define-based Join
  1. Click the Join options tab in Report Assistant or Graph Assistant and click New.

    The WebFOCUS masters list dialog box opens where you select a target data source.

  2. Select a data source and click OK.
  3. Click the down arrow of the Define icon and then click New define field.

    The following image shows the list of Define field options.

    The following image shows the Define Field Creator dialog box where you create the Define expression.

  4. Create the defined field. The new define field appears in the Available fields list. The field is prefixed with the define symbol.
  5. Add the defined field and the target field to their respective Selected Fields boxes.

    Note: Fields must have the same format and be indexed fields in order to use them to create joins.

  6. If you want to see the syntax, click View to display the define-based join syntax.
  7. Give the join a meaningful and unique name in the Description box.
  8. Click Save & Create. The new join appears in the Joins list.
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Procedure: How to Create Multi-field Joins
  1. Click the Join options tab in Report Assistant or Graph Assistant and click New.

    The WebFOCUS masters list dialog box opens where you select a target data source.

  2. Select a data source and click OK.
  3. Enter multiple fields in the Host field list box and one field in the Target field list box.
  4. If you want to see the syntax, click View to display the multi-field join syntax.
  5. In the Description box, give the join a meaningful and unique name.
  6. Click Save & Create.

    The new join appears in the Joins list.

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Procedure: How to Delete a Join
  1. Select a join from the Select an existing join list box.
  2. Click Delete.
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Procedure: How to Edit a Join
  1. Select a join from the Select an existing join list box.
  2. Make your desired changes.
  3. Click Save & Create.
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