# Lookup

In this document, you’ll learn how to use the *Lookup* transformation in Astera Dataprep to enrich a dataset by bringing in additional fields from another source.

### Use Case

A university maintains a student's dataset, but roll numbers are stored separately. To prepare data for reporting and transcripts, the university needs to enrich the student's dataset with roll numbers, ensuring each student is matched correctly. 

This lookup source may exist as a file, a shared project source or in a database table. 

1. In the toolbar, click on *Lookup* and select the appropriate source type.
2. This will open the *Recipe Configuration – Lookup* panel. In this panel you can configure the source-specific settings (see tabs below).

{% tabs %}
{% tab title="File " %}

<figure><img src="/files/0VVYeFlEo49WmEFNT2iX" alt="" width="431"><figcaption></figcaption></figure>

* **Browse Path**: Use this to manually browse and select your source file.
* **Path from Variable**: Use this when your file path is dynamic and parameterized. To learn more about using variables click [here](/dataprep/variables.md#using-variables-in-recipes).

For this use case, we’ll use the *Browse Path* option.

<figure><img src="/files/EBkSWIR4EXv5T7RHxzvR" alt="" width="429"><figcaption></figcaption></figure>
{% endtab %}

{% tab title="Project Source" %}

* **Lookup Source:** Choose the source you want to use for your Lookup. All available sources will be visible in the drop-down.

<figure><img src="/files/FOnoB8q7tQLpdAOpnhnU" alt="" width="388"><figcaption></figcaption></figure>
{% endtab %}

{% tab title="Database Table" %}

* **Connection Name:** Select the shared connection you want to use. The drop-down lists all shared connections available in the project.

<figure><img src="/files/COsaDN73xkmpjPU5lyhK" alt="" width="428"><figcaption></figcaption></figure>

* **Table:** From the drop-down, choose the database table you want to lookup from with. In this example, we’ll select the *RollNo* table.

<figure><img src="/files/GmaVwO6lBRxbBVsL1qMq" alt="" width="433"><figcaption></figcaption></figure>
{% endtab %}
{% endtabs %}

* Provide a name for the lookup dataset (or keep the default name).

<figure><img src="/files/p4qQDWEIiMJNPTn1YNaQ" alt="" width="346"><figcaption></figcaption></figure>

* **Keys:** Select the key fields to define how records will be matched. Astera will auto-detect matching fields, but you can modify them as needed.

  <figure><img src="/files/G8PrT2ecTXyIi8pmbJOD" alt="" width="391"><figcaption></figcaption></figure>

  * **Current Dataset Column**: Field from the current dataset.
  * **Source Column**: Field from the lookup dataset.
* **Return Columns:** Choose which columns to return from the lookup source.

<figure><img src="/files/SDjHNKGHDNcdaRKUiR7i" alt="" width="394"><figcaption></figcaption></figure>

3. Once you’re done, click <img src="/files/BYTMKwUdAnoNo8Mc0TJm" alt="" data-size="line"> *Apply.* The result will appear in the grid with the new column(s) added.

<figure><img src="/files/WDz9ogveANfAAOzKvoIp" alt=""><figcaption></figcaption></figure>


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# Agent Instructions: Querying This Documentation

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```
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Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.