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Talend Open Studio Cookbook by Rick Barton

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Hierarchical joins using tMap

The previous recipe covered the basics of tMap joining, but tMap has another level of joining capability, in that it can join together data in a hierarchical fashion. This simple example shows how easily this can be achieved using tMap.

Getting ready

Open the job jo_cook_ch04_0080_hierarchicaltMapJoin.

How to do it...

  1. Open the tMap component. You will see three input tables.
  2. Select customerId from the customer table and drag it into Expr. key of the customerId in the order table.
  3. You will see that a join link, a purple key symbol has been added to the column.
  4. Change the tMap settings for the order table to Inner Join and All Matches (see previous recipe if you are not sure how to do this)
  5. Now, select orderId from the order ...

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