Understanding Database Relationships in Bubble.io   Before diving into managing database relationships, it's essential to understand the concept. Relationships between data types in Bubble.io resemble relationships in traditional databases, such as one-to-one, one-to-many, and many-to-many. These relationships help establish connections between different data types, ensuring that your application can efficiently store and query related data.   Setting Up Data Types   1. Create Data Types   - Go to the Data tab in the Bubble editor. - Click on "Data types". - Add new data types by clicking "Create a new type". Name it accordingly (e.g., "User", "Order", "Product").   1. Add Fields to Data Types   - Once you have your data types, click on each of them to add fields. - Click "Create a new field" and specify the field name, type, and options.   Establishing One-to-One Relationships   1. Define Field in One Data Type   - Select one of your data types (e.g., User). - Create a new field that references another data type (e.g., Profile). - Set the field type to the data type you want to link to (e.g., "Profile").   1. Set the Field Type   - Ensure that the field is set to singular data type relationship and not a list. - For example, a User can have a Profile, and each Profile belongs to one and only one User.   Establishing One-to-Many Relationships   1. Add List Field in Primary Data Type   - Select the primary data type where you will have the list (e.g., User having many Orders). - Create a new field called "Orders". - Set the field type to the other data type (e.g., "Order"), and make sure to select it as a list (enable the checkbox "This field is a list").   1. Link Back From Secondary Data Type   - Optionally, you might also want the "Order" data type to reference the "User". - Create a field in the "Order" data type called "User". - Set the field type to "User" to establish the relationship both ways.   Establishing Many-to-Many Relationships   1. Create Linking Fields in Both Data Types   - For many-to-many relationships, each data type will hold a reference to the other. For example, a User can have many Products, and a Product can have many Users.   1. Add Fields   - In the User data type, create a new field called "Products". - Set the field type to "Product" and make it a list. - In the Product data type, create a new field called "Users". - Set the field type to "User" and make it a list.   Populating Relationships in Workflows   1. Modify Relationships in Workflows   - Navigate to the "Workflow" tab. - Set actions to modify the relationships appropriately. For example, when creating a new order, you will want to add this order to the user's list of orders. - Utilize the "Make changes to a thing" action to update fields that hold references to other data types.   1. Adding Items to a List   - When you need to add an item to a list (e.g., adding an Order to a User), use the “Add” action in workflows. - Select the appropriate list field (e.g., User's Orders) and specify the item to add.   Testing and Querying Relationships   1. Run Tests in Preview Mode   - Use Bubble's preview mode to test your data relationships. - Create new entries and verify that the relationships are correctly stored.   1. Query Data with Constraints   - Use Bubble's search function with constraints to query data based on established relationships. - For example, to display a User's Orders, set a repeating group data source to search for Orders with a constraint that matches the current User.   By carefully setting up and managing your database relationships in Bubble.io, you ensure that your application is scalable and efficient.