Overview

Use an ERD to define the structure of the data that backs your application. For an introduction to ERD concepts and why ERDs are important, see Understanding ERDs.

The process for creating an ERD is slightly different depending on whether or not you have already created tables in PhixFlow.  The following table summarises the different ways you can add data to an ERD, depending on your starting point:

Creating Tables in an ERD

Create a Table using CSV or Excel Data

1. Drag a CSV or Excel file directly onto an ERD canvas.
2. PhixFlow will create a table automatically based on the information in the file.

This is covered in the ERD Fundamentals video course found here: Entity Relationship Diagrams.

Create a New Table

1. Drag 

   Insert excerpt
   _table_new _table_new nopanel true

     from the toolbar into the diagram.
2. In the pop-up, enter a name that reflects what the table will represent. For example Customer.
3. PhixFlow opens the properties tab for the new table on the right and adds the table to the canvas.
   The table header displays its name. PhixFlow automatically adds 2 attributes:

1. • UID, a primary key that is a unique identifier for each record.
   • Name,  a display name which in a view or form will be used to provide a user-friendly name to the user in place of the numeric UID.
2. To add attributes to the stream:
   1. In the stream, click 

      Insert excerpt
      _new _new nopanel true

      . PhixFlow opens the attribute properties on the right, with the default settings of:
      • Type = String
      • Length = 50 characters.
   2. In the properties, enter the Name and select appropriate type properties, such as Date or Integer; see Attribute. The following data types have additional properties:
      • For String add Length
      • For Integer add Precision
      • For Decimal add Significant Figures and Decimal Places
   3. Click 

      Insert excerpt
      _finish _finish nopanel true

       to save the attribute properties.
3. PhixFlow adds the attribute to the stream in the ERD.

Add an Existing Table

1. In the toolbar, click 

   Insert excerpt
   _table_list _table_list nopanel true

   .
2. PhixFlow filters the repository to show the list of tables available in this application.
3. Drag the desired table from the repository onto the ERD canvas. 

Create Relationships

In an ERD you can create a one-to-many relationship between a primary key in one table with an attribute in another table. For relationship concepts, see Understanding ERDs.

To create a relationship

1. Click-drag from one attribute to another.
   1. One of the attributes must be a primary key.
2. PhixFlow highlights the attribute when your mouse pointer is over it. 
3. When the destination attribute is highlighted, release the click.

Relationships

See the table below for the relationships that can be created between attributes:

Relationship Restrictions

PhixFlow cannot create a relationship between your selected attributes if your selected foreign key attribute: 

• is already a foreign key to a different primary key.
• has a different Data Type and type properties to the primary key.

If this happens, you can:

• create a new attribute to be the foreign key.
• change the foreign key attributes to match the primary key, provided there is no data in the table.
• create the relationship with a different attribute.

To change the data type properties, In the ERD, click on an attribute to open its properties.

Show Relationships From Other ERDs 

Anchor
erd-view erd-view

If a table appears on more than one ERD it may have relationships with tables that are not visible in your current ERD. To see other related streams, right-click a table to show the context menu and select:

• Insert excerpt
  _rel_in _rel_in nopanel true

• Insert excerpt
  _rel_out _rel_out nopanel true

PhixFlow adds the related tables to your ERD. 

To keep the related tables in your ERD, in the toolbar, click 

To remove the related table from your ERD, in the toolbar, click 

Saving ERDs

Changes to an ERD are automatically saved.

Accessing Properties

You can set properties for all the items in an ERD. To access properties:

• ERD: in the canvas toolbar click

  Insert excerpt
  _property_settings _property_settings nopanel true

• Table : in the ERD, click on the stream header or right-click to open the pop-up menu and select 

  Insert excerpt
  _config _config nopanel true

• Attribute: in the stream, click on an attribute

PhixFlow opens the properties panel on the right.

Rearranging ERDs

To move streams around in the ERD, click on the header and drag the stream. There are also Align options in the toolbar that you can use to line up or distribute selected streams.

If you want to highlight the relationships that affect a stream, click the stream to select it. The following screenshot shows the Teacher stream is selected.

Image Removed

• Blue lines indicate relationships to a foreign key in the selected stream
• Green lines indicate relationships from the primary key in the selected stream.

If a stream has a lot of attributes that you do not need to see, collapse the list to show only the stream's primary and foreign keys.

• Either right-click on a stream and select Hide attributes or Show attributes
• Or double-click on the stream header.

To select multiple streams, draw a square around them. 

Image Removed

By default, relationships are straight lines, but you can change them to have angles.

1. Click on a relationship line to add an angle point, which appears as a blue dot; see the screenshot on the left.
2. Move the mouse pointer over the blue dot. It changes to a four-way arrow to indicate you can drag.
3. Drag the point to the position you require. 

To remove an unwanted angle, right-click the blue dot and select Remove Point; see the screenshot on the right.

Hover your mouse pointer over
an angle to see the blue angle point.

Image Removed

Right-click the blue angle point to see the Remove option

Image Removed