# Join Using a File
In this document, you’ll learn how to use the *Join* function in Astera Dataprep to combine a dataset from a file source with an existing dataset in your Dataprep Recipe.
### Use Case
In this use case, we have a Dataprep Recipe where a Company’s *Transactions* dataset has been cleansed and aggregated. Now, they want to join it with their *Portfolios* dataset, which is available in a csv file.
1. To begin, click on the *Join* option in the toolbar and select *File* from the drop-down.
2. Alternatively, you can drag and drop the file from the *Data Source Browser* panel onto the Join object in the Recipe canvas.
3. This will open the *Recipe Configuration – Join* panel.
4. In this panel, you’ll configure the following options:
* **File Location:** Choose how you want to locate your file:
* **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 parametrization click [here](/miscellaneous/parameterization.md).
For this use case, we’ll use the *Browse Path* option.
* **Join Dataset:** You can provide a custom name for the joined dataset or keep the default name. In this example, we’ll keep the default name.
* **Join Type:** Choose the type of join you want to perform:
* **Inner**: Keeps only the records that have matching values in both datasets.
* **Left Outer**: Keeps all records from the current dataset and adds matching data from the joined dataset. Unmatched records from the joined dataset are filled with nulls.
* **Right Outer**: Keeps all records from the joined dataset and adds matching data from the current dataset. Unmatched records from the current dataset are filled with nulls.
* **Full Outer**: Keeps all records from both datasets. Unmatched values are filled with nulls.
In our example, we’ll use an *Inner* join to include only matching records.
* **Keys:** Specify the key fields that the join will be based on. Astera will auto-detect matching fields, but you can modify them as needed.
* **Left Field**: Field from the current dataset.
* **Right Field**: Field from the joining dataset.
In this case, we’ll keep the default key fields selected.
5. Once you’re done, click 
*Apply.* The file source dataset will now be joined, and the result will appear in the grid.
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