.. _auto_dataset_add_static_column:

*COMBINE DATASETS BASED ON PRIMARY KEYS*
========================================

Appends a new column with a single constant value to every row of the input dataset. Use this worker when you need to tag or annotate a dataset with a fixed label, identifier, or scalar constant before joining or downstream processing.

When to use
-----------

Classification: **process**.

Tagged: ``add_column``, ``annotation``, ``column``, ``constant``, ``dataset``, ``static``, ``tagging``, ``transform``.

Inputs
------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20 20 20

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Dataset1
     - dataset1
     - dataset
     - —
     - 
     - Input dataset to which the new static column will be appended; accepts any tabular dataset available in the workflow.
   * - Col Name
     - col_name
     - scalar
     - —
     - 
     - Name of the new column to add (string, e.g. 'source' or 'scenario_id'); must be a valid column identifier and should not conflict with existing column names.
   * - Column Value
     - column_value
     - scalar
     - —
     - 
     - Constant scalar value to populate in every row of the new column (string or numeric, e.g. 'baseline' or '1'); the same value is written to all rows.

Outputs
-------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20

   * - Label
     - ID
     - Type
     - Description
   * - dataset_add_static_column_output_1
     - dataset_add_static_column_output_1
     - dataset
     - Output dataset identical to the input but with the new constant-value column appended as the last column.

Disciplines
-----------

- data.dataset.transform

Runnable example
----------------

A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: `/api/workflow/example?id=dataset_add_static_column <https://www.d3view.com/api/workflow/example?id=dataset_add_static_column>`_

.. raw:: html

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   Auto-generated from <code>transformation</code> schema. Worker id: <code>dataset_add_static_column</code>. Schema hash: <code>71c1dda542bc</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>