---
title: 'Data Sources overview'
description: 'NocoDB Data-Source sync, access control & re-config'
---

## Overview

`Data Sources` tab includes following functionalities
- Connect/manage external data source
- UI Access Control
- Relations

Note that, currently only one external data source can be added per project.

## Accessing Data Sources

Click `Data Sources` tab in `Project dashboard`

![data source](https://github.com/nocodb/nocodb/assets/86527202/fde9de36-93cd-4b9a-adbe-48666daa009d)

## Sync Metadata

Go to `Data Sources`, click ``Sync Metadata``, you can see your metadata sync status. If it is out of sync, you can sync the schema. See [Sync Schema](/setup-and-usages/sync-schema) for more.

![sync metadata](https://github.com/nocodb/nocodb/assets/86527202/2df4687f-c349-4fd5-a50c-9c6161d87795)

## UI Access Control

Go to `Data Sources`, click ``UI ACL``, you can control the access to each table by roles.

![ui acl](https://github.com/nocodb/nocodb/assets/86527202/2368a543-b985-4adc-8650-5447bf7ee55b)


## Relations

Go to `Data Sources`, click ``Relations``, you can see the ERD of your database.

![relations](https://github.com/nocodb/nocodb/assets/86527202/c3775d27-f75d-4263-8903-dd66427de4b4)


### Junction table names within Relations

- Enable `Show M2M Tables` within `Project Settings` menu
- Double click on `Show Columns` to see additional checkboxes get enabled.
    - Enabling which you should be able to see junction tables and their table names.

![image](https://user-images.githubusercontent.com/35857179/219832436-9c1311c3-854c-4b31-9c94-8035dfba2a2b.png)

## Edit external database configuration parameters

Go to `Data Sources`, click ``Edit`` icon, you can re-configure database credentials.  
Please make sure database configuration parameters are valid. Any incorrect parameters could lead to schema loss!

![edit db config](https://github.com/nocodb/nocodb/assets/86527202/8a609529-e4b9-4869-95ce-90bc1b4cfe4d)

## Unlink data source

Go to `Data Sources`, click ``Delete`` against the data source that you wish to un-link.

![datasource unlink](https://github.com/nocodb/nocodb/assets/86527202/39ba34d9-9e00-4bac-996c-48c08c8fc049)


## Data source visibility

Go to `Data Sources`, toggle ``Radio-button`` against the data source that you wish to hide/un-hide.

![datasource visibility](https://github.com/nocodb/nocodb/assets/86527202/d7da4046-4755-484e-877c-bd80dfcbeded)