This page is for application designers who want define the data that will back the application. It explains how to draw an ERD and setup its properties.

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 things you need to consider when defining an ERD depend on whether or not you have already loaded data into PhixFlow.

If you do not have any data for your application or it has not been loaded yet:
1. Create tables, attributes and relationships in the ERD.
  - New tables have an attribute called UID, which is the primary key.
  - Make sure the data Type is correct for the data that will populate each attribute.
  - PhixFlow adds table items to the repository. Attributes are listed within the Table properties.
  - Relationships are not listed in the repository. To see relationship properties, in the ERD, click the relationship arrow.
2. Add records to your tables:
  - either manually
  - or from an external source, e.g. Excel file, database etc.
If you have already loaded data, the tables are listed in the repository.
1. Drag tables from the repository Data → Tables into the ERD canvas.
2. Set the primary key:
  - Either create an attribute called UID that PhixFlow will populate with unique values for each record
  - Or select an attribute to be the primary key. You will need to ensure this contains unique values.
3. Add relationships
  - Primary key and foreign key attributes must have the same data Type.

Sections on this page

How to Define an ERD

Open an Existing ERD

From the home menu, select Data and click on an ERD in the list.
In the repository, open your application and find Data → ERD.
- either right-click on an ERD name and select Display.
- or double-click the ERD name to open the properties. In the properties toolbar, click the ERD icon.

Create a New ERD

From the home menu, select Data.
PhixFlow displays the list of ERDs. Select Create New from the left hand side.
In the pop-up, enter a name for your ERD, and a description then click .
PhixFlow opens a new ERD canvas on the left with a toolbar at the top. Hover your mouse pointer over toolbar icons to display a tooltip.

Add an Existing Table

In the toolbar, click Table List
PhixFlow filters the repository to show the list of tables available in this application.
Drag a table from the repository onto the ERD canvas.

Create a New Table

Drag Table Create from the toolbar into the diagram.
In the pop-up, enter a name, for example "Customer" and click .
PhixFlow adds the table to the canvas and opens its properties tab on the right.
- Name - displays the name entered in step 2.
- UID - the unique identifier and primary key.
To add attributes to the table:
1. In the table, click Add New. PhixFlow opens the attribute properties on the right.
2. In the properties, enter the Name, Type and Length for the data; see Attributes.
  PhixFlow creates attributes with a Type or String and Length of 50 characters. Remember to select appropriate type properties for an attributes data, such as Date or Integer.
3. the attribute properties.
PhixFlow adds the attribute to the table in the ERD.

Changes to tables, attributes and relationships are automatically saved to the ERD. However, you must click Apply to keep any changes you make to the layout, such as moving tables or adding corners to relationships.

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, click-drag from one attribute to another.

More detail

Click on the source attribute.
Drag to the destination attribute. PhixFlow highlights the attribute when your mouse pointer is over it.
When the destination attribute is highlighted release the click.

Rearranging ERDs

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

To select multiple tables, draw a square around them.

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

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

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

either right-click on a table and select Hide attributes or Show attributes
or double-click on the table header.

By default, relationships are straight lines, but you can change them to have angles (shown in the screenshot on the left).

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

To remove an unwanted angle, right-click the blue dot and select Remove Point (shown in the screenshot on the right).

Properties

Parent Details

If this item is within or belongs to another, its parent name is shown here. See the Parent Details section on the Common Properties page for more details.

Basic Settings

Field	Description
Name	The name for the ERD.

Description

We recommend that you always enter a description to explain the purpose of this item.

Audit Tab

Audit Summary

See the Common Properties page, Audit Summary section.

How PhixFlow Manages Different Relationship Drags

Drag		Relationship line	Foreign key type If PhixFlow does any automatic changing of types, then record them here
From table1	To table2	Relationship line
primary key	attribute	table1.primarykey → table2.attribute one → many	Table has no records: Table has records: 21052021 PhixFlow creates relationships with types that don't match
attribute	primary key	table2.primarykey → table1.attribute one → many
primary key	primary key	table1.primarykey → table2.primarykey one → one	21052021 should this work?
attribute	attribute	if table1 has no primary key: PhixFlow makes the table1.attribute the primary key if table 1 has a primary key: relationship is from table1.primarykey instead of from table1.attribute.

ERD Toolbar

The toolbar is at the top of the canvas. Hover your mouse pointer over the toolbar to see a tooltip.

Option	Description
Create
Create	Drag this icon onto the canvas to create a table.
Screen	Creates a new screen for the selected table.
List
Tables	Click to see a list available tables.
Screens	Click to see a list available screens.
Canvas
Save	Save changes to the diagram. If there is no save icon, PhixFlow is saving changes automatically.
Refresh	Redraw the ERD to display recent changes to the diagram.
Properties	Open the properties for the current diagram.
Zoom out	Zoom out to see more of the diagram, with smaller text.
Zoom in	Zoom in to see a smaller area of the diagram, with larger text.
Ungroup	Select a grouped set of items and then click to ungroup them. Select several items then click to group them together.
Group	Select several items then click to group them together.
Back	For screen layout, move a component back.
Forward	For screen layout, bring a component forward.
Align options	Click/hover to show all the options for aligning items on the canvas.
Align Grid	Organise selected items into a grid pattern.
Align left	Align selected items to the left.
Align right	Align selected items to the right.
Align top	Align selected objects to the top.
Align bottom	Align selected objects to the bottom.
Distribute horizontally	For 3 or more items, distributes the selected items evenly between the left and right items.
Distribute vertically	For 3 or more items, distributes the selected items evenly between the top and bottom items.

Table Pop-up Menu

You can access more options in a pop-up menu:

in the table header, click More Options
right-click anywhere in the table.

Option	Rename to	Description
Configure Table	Table properties	Open the properties for this table.
Remove this item from the Diagram	Remove from ERD	Remove the selected item(s) from the diagram.
Hide Attributes	Hide attributes	Collapse the table so that it only shows the table name, primary key and any foreign keys. Other attributes are hidden.
Show Attributes	Show attributes	Expand the table to show all the attributes
Parmanently Delete	Delete everywhere	DDelete the selected item(s) from the ERD and from everywhere it is used.

Defining Data Structures using ERDs