Overview

PhixFlow Entity Entity Relationship Diagrams (ERDs) define the logical structure of the data in your application. "Entities" are displayed as tables and represent the "things" in the world that you want to represent as data.

show as data.

Opening and Creating ERDs

• On your application's home page, click

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   to list the existing ERDs.
  • Alternatively, click

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     from the header bar. 
• To create a new ERD, click the 

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  button.
• To open an existing ERD, double-click it.

ERD Layout

Here is a simplified view of the ERD window:

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1. Toolbar: This contains ERD-specific options to add data to the ERD and move tables on the canvas.
2. Repository: On the toolbar, click

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    to list all available tables in the r Repositorypane on  on the right. The main part of the window is the canvas, where you create the ERD.To add a new table, from the toolbar, drag the . These can be dragged and dropped onto the canvas.
3. Canvas: This is where you create and modify your ERD.
4. Table: This is represented as a box, containing a list of all of the attributes within the data and their associated data type (e.g. string). 
5. Relationship: This is represented as a line connecting the tables.
6. Options: View the data in the table by clicking 

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   tables

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   tables

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    icon onto the canvas.To add an existing table, on the toolbar, click  or show all table options by clicking 

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   .

Tables

A table is where your data is stored for your application.

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Attributes

Attributes represent the different pieces of data recorded in the table, and can be thought of as column headers on a spreadsheet.

• Attributes are configured with a data type (e.g. string) and properties. To change these, click on the attribute's name. See Understanding Data Types.

Primary Keys

Primary Keys are special attributes which uniquely identify each record.

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Table Relationships

1. A table is represented as a box, containing a list of all of the attributes it contains and their associated data type.
2. A line connecting tables represents the relationship between them. The line connects the primary key of one table to a foreign key in a different table; see Relationship.

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ERD Example

The following example shows an ERD for a school. Here the school has entities: departments, teachers, students, classrooms and so on. All these entities are represented as tables and the lines connecting them show their relationships to one another. We can see from this diagram that a School Department has many Classrooms and Teachers. This example is covered in detail in Understanding ERDs.

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Creating an ERD and Opening an Existing ERD

Already Have Data?

If you have data to import into PhixFlow, such as a database or API, use an Analysis Model to import it. This allows you to configure connectors to access your existing data and store the data as tables in PhixFlow's own database. See Importing Data and Importing Data Through an API.

You can also use an Analysis Model to set up bulk processes to manipulate large volumes of data before it is presented to your users. See Analysis Models for Batch Processing Data.

What's Next?

Understanding ERDs covers ERDs in more depth to help you design your own ERDs and views to display your data. 

• When you create a new table, PhixFlow adds an attribute called UID and configures it as follows:

  • the table's Primary Key
  • an integer
  • automatically creates a unique number for every record in the table
• If your data already has a unique attribute, you can use this as the Primary Key by right-clicking and selecting Make Primary Key. 
  • On the example image above, the Teacher table has the attribute UID (Unique IDentifier) as the Primary Key. This is because teachers may have the same first and/or surname, so these attributes cannot be guaranteed to be unique and therefore cannot be a Primary Key.

Display Names

Display Names are special attributes which are displayed instead of a Primary Key, as they make more sense to a human.

• When you create a new table, PhixFlow adds an attribute called Name and configures it as the Display Name.
  • This is then shown in place of the Primary Key when displayed on a screen. Display Names do not need to be unique and should be user-friendly.
• If your data already has an attribute you want to use as the Display Name, right-click it and select Make Display Name. 

Foreign Keys

Foreign Keys are attributes in one table that relate to the Primary Key in another table.

• Foreign Keys must have the same data type and properties as the corresponding Primary Key. For example, both must be strings of the same length.

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Validation

Validation is applied to table attributes and determines the criteria an attribute must satisfy in order to be considered valid. For example, the attribute is mandatory, must contain a minimum number of characters or must adhere to a specific pattern. Validation added to a table will be applied wherever the attribute is updated, such as when saving data on an input screen. See Table Attribute Validation.

Indexing

Indexes are applied to attributes on a table and help improve the speed of data retrieval. They work like the index of a book. Users do not see the indexes, they are used internally by PhixFlow. Updating a table with indexes takes more time than one without, as the indexes also need to be updated. Therefore, indexes should only be created on attributes that will be frequently searched against. See Indexed on Attribute.

Relationships Between Tables

Tables in PhixFlow are relational, which means that information in one table can be related to information in another table. Data can then be accessed in many different tables without requiring duplication.

A line connects the Primary Key of one table to a Foreign Key in a different table, and represents the relationship. See Relationship.

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One-to-many and Many-to-one

The relationship line between a Primary Key and Foreign Key represents a one-to-many relationship. In the below example, one teacher runs many courses.

A many-to-one relationship is implied when you read a relationship in the opposite direction. In the below example, a department has many teachers, and several teachers work for one department.

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Many:many 

Many-to-many relationship can be supported with an intermediate table.

Working in an ERD

You can add tables in an ERD manually. See Adding Content to an ERD.

• Create a new table by dragging 

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   from the toolbar onto the canvas.
• Add an Excel spreadsheet by dragging it onto the canvas. PhixFlow imports the data and creates a new table.
• Add an existing table by clicking 

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   in the toolbar. The available tables are listed in the Repository and can be dragged onto the canvas. See 2. Importing Data.

View Table Data

Select 

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Create a Screen from a Table

Select 

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Multiple ERDs

The same table can appear on multiple ERDs.

ERD Example

What's Next?

Fundamentals Course

Further Reading