QlikView- Mapping Tables

In Qlikview it is always advisable to minimize the number of tables in the data model.

Mapping Tables are used in QlikView to clean up the data model.

Tables with just 2 columns can be removed and columns of that table can be mapped to another table.

Mapping tables are stored in a separate area in memory and used only as mapping tables during script execution. After script execution they will be automatically dropped.

Please watch my video for more details

Further readings : Don’t join – Use Applymap instead

2 thoughts on “QlikView- Mapping Tables

  1. Hi,
    when would you chose to use MAPPING instead of a JOIN to reduce the number of tables in the data model?

    The only advantage I can see is that you can use the ApplyMap command to guarantee the returned column has a default value while if a join were used, you could have a NULL value on the join for a column where no match is found.

    So in the line below we would get ‘Unknown’ in the MyColumn using MAPPING but if I used a JOIN I would get a NULL.

    ApplyMap(‘MapTable’,MapField,’Unknown’) AS MyColumn

    Is this the key advantage or is there something else I am missing?

    • Roy:
      Mapping and ApplyMap should always be preferred over join.
      To help you better understand, I am quoting below from HIC. I will put a link to his blog on this subject.

      Whenever you want to fetch one single value per record use ApplyMap().
      The only time that you cannot use Applymap() instead of a join is if you want to fetch more
      than one single corresponding value (record) from the second table.

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