> For the complete documentation index, see [llms.txt](https://docs.reorc.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.reorc.com/data-modeling/sources.md).

# Sources

A source is a reference to raw tables from database that you can use in your models. 

<figure><img src="/files/dcaGka1Zz0wR7dneorx4" alt=""><figcaption></figcaption></figure>

In traditional SQL transformation, raw tables are typically referenced directly by their names. This leads to a few challenges, such as code readability and dependency management between tables. In contrast, sources introduce a more structured and modular way to reference raw tables, providing several benefits:

* **Clear data lineage**: Sources help you explicitly identify raw tables as external data sources. This helps establish clear data lineage, making it easier to trace data from raw tables to the transformed models.
* **Data testing**: Declaring raw tables as sources allows you to implement data tests. You can validate assumptions about the data quality, ensuring transformations applied later are based on trusted data.
* **Improved communication**: In source metadata, you can add descriptions, owners, and other information to clearly express your use cases. This creates transparency and improves communication across teams.

## Create a source

To create a source, follow these steps:

1. In the **Models** tab, click on the **+** icon and select **Add source**.&#x20;
2. In the opened modal:
   1. Select the connection type. Currently, ReOrc supports referencing from a warehouse.
   2. Select the target connection. If you haven't set up the project connection, refer to: [Project connections](/connections/project-connections.md).
3. Click **Next**. ReOrc then displays all the tables available from the target connection.

<figure><img src="/files/0POYEIKmvIEKp2MByjLW" alt=""><figcaption><p>Select tables from a connection</p></figcaption></figure>

4. Select the desired raw tables or models.
5. Click **Add source**.

The selected tables will then be added to the **sources** folder and grouped by connection name.

<figure><img src="/files/pOjnzJPMRA7gBGjMpiC3" alt=""><figcaption></figcaption></figure>

You can view the schema of a source by opening it in the editor. A schema contains field name (or column name), data type, and comment.&#x20;

## Select from a source

With raw tables organized by sources, you can reference them in a model using the `{{ source() }}` Jinja function. For more details, see: [Models](/data-modeling/models.md).

The function requires two arguments:

* `source_name`: the folder name that contains the source.
* `table_name`: the name of the table.

For example, with the `raw_orders` table added under the `jaffle_shop` folder, we can reference it as follows:

```sql
select 
    id as order_id,
    customer as customer_id,
    ordered_at as order_date

from {{ source("jaffle_shop", "raw_orders") }}
```

The above model is then compiled to:

```sql
SELECT
  id AS order_id,
  customer AS customer_id,
  ordered_at AS order_date
FROM
  `jaffle_shop`.`raw_orders`
```