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 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 tables to an ERD, depending on your starting point. (See the sections below for details of how to add tables and relationships.)

Sections on this page

Starting Point

Process

Primary Key

See

I have no data

Define the tables, attributes and their relationships in the ERD.

Later you will need to add records to the tables:

either manually, for example create a screen in which application users can enter data.
or via an analysis model.

PhixFlow automatically creates each table with:

a primary key called UID
a Name attribute
the Name attribute set as the display name; see Display Name.

Defining Data Structures using ERDs

Creating a Screen from a Table
Load Data

I have data but it's not in PhixFlow

Use an analysis model to connect to your data. PhixFlow can read the data structures to create tables. When you run analysis on the model, PhixFlow loads the data records.

In each table:

either set one attribute as the primary key and ensure all values will be unique
or add an attribute called UID with
- Data Type = Integer
- Precision = 10
Set one attribute to be the Display Name.

Load Data

I have tables in PhixFlow already

In the ERD toolbar, click List Tables to display a list of all the tables. Drag tables into the ERD and then add the relationships.

Defining Data Structures using ERDs

PhixFlow cannot ensure unique values for a primary key where:

the name is UID but its data type is not integer
the name is not UID

If your data already has a unique attribute, you can use that as the primary key. For example, the Teacher table could have a National Insurance attribute, which would be unique to a teacher. In this case, you must set up your own processes to make sure that the records in a table all have unique values in the primary key.

How to Define an ERD

Open an Existing ERD

In the repository, find 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 Display icon.

Create a New ERD

In the repository, find ERD. Right-click to display the context menu, and select Add New
Enter a name for your ERD, and a description then click Apply and Close.

When you are creating tables, choose a name that reflects the entity your table represents.
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 List Tables.
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 Create New Table from the toolbar into the diagram.
In the pop-up, enter a name, for example "Customer", and click .
PhixFlow opens the properties tab for the new table on the right and adds the table to the canvas.
The header displays the name entered in step 2. PhixFlow automatically adds 2 attributes:

- UID - PhixFlow requires a unique identifier and primary key for each table.
- Name - PhixFlow sets the Name attribute to be the display name. In data grids and forms etc. PhixFlow uses this attribute to provide a user-friendly name, rather than a numeric identifier. Optionally, change the attribute name.
To add attributes to the table:
1. In the table, click Create New. 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 Attributes. 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 Apply and Close to save the attribute properties.
PhixFlow adds the attribute to the table in the ERD.

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.

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

Drag		Relationship line
From table1	To table2	Relationship line
primary key	attribute	table1.primarykey → table2.attribute 1:many
attribute	primary key	table2.primarykey → table1.attribute 1:many
attribute	attribute	if table1 has no primary key: PhixFlow makes the table1.attribute the primary key if table 1 has a primary key: the relationship is from table1.primarykey instead of from table1.attribute.

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.

In these cases, PhixFlow reports an error: Related attributes must have the same type and length. This type/length is different.

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.

If you have created several ERDs to define the data structure that your application requires, then each ERD is a view onto a part of the full data structure.

Saving ERDs

Changes to tables, attributes and relationships are automatically saved. However, to keep any changes you make to the layout, such as moving tables or adding angle points to relationships, remember to click Apply in the toolbar. PhixFlow notifies you if there are unsaved changes when you attempt to close an ERD.

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.

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, 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.

To select multiple tables, draw a square around them.

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

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

Click on a relationship line to add an angle point, which appears as a blue dot; see the screenshot on the left.
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; see the screenshot on the right.

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

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.

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 options
Table	Drag this icon onto the canvas to create a table.
List options
Table	Click to open the repository filtered to list the tables available in your application.
Canvas options
Help	Open the help topic with details about working with ERDs.
Arrange Selected Items	Options to arrange the selected tables in the ERD: Align to Grid Align Objects to Left Align Objects to Right Align Objects to Top Align to base Error rendering macro 'excerpt-include' : No link could be created for '_distribute_horizontal'. Error rendering macro 'excerpt-include' : No link could be created for '_distribute_vertical'.
Properties	Open the properties tab for the ERD.
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.
Apply	PhixFlow automatically saves changes to tables and relationships. Use this icon to save layout changes to the ERD.
Refresh	Update the ERD to the last saved layout. This clears any unsaved layout changes. Your ERD should automatically show an changes elsewhere in PhixFlow. For example, if someone adds a new attribute to a table in your ERD, the attribute will appear on the list. If changes are not appearing, click this icon.
Ungroup Not available??	Select a grouped set of items and then click to ungroup them. Select several items then click to group them together.

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Menu option	Description
Delete	When a specific component is selected, delete the component. Other delete options that may be available relate to specific types of component in the selected pane.
Delete Element	Delete a pane or dashboard element from the layout. Check whether Remove Element from Dashboard is also going??
Delete	Delete a form component from the layout.
Create New Form	Create a new form in the current area.
Pin/Unpin Selected Objects	Fix the position of selected objects. ??Going away??
Palette	Open the palette to drag in components.
Turn Auto Size Off/On	Toggle whether or not the currently selected component is automatically autosized when an application window is resized by the user. Using this option, or manually resizing a component may change the state of the Layout → Style Settings → Auto Size property.
Arrange the selected items	Options to arrange the selected components within a pane: Align Objects to Left Align Objects to Right Align Objects to Top Align to base Error rendering macro 'excerpt-include' : No link could be created for '_distribute_horizontal'. Error rendering macro 'excerpt-include' : No link could be created for '_distribute_vertical'.
Find in Repository change to Show in layers??	Open the repository with to see the selected component in the list. This can be useful if you want to move a component.
Screen Properties	Open the properties tab for the screen.
Show Record Details	Display information about the table and its records. Check this option's name has changed??
Select all children	For the selected parent container, select all the child components too.
Show Attributes for <table name>	Open the list of attributes for the table. This option is available when a screen is backed by a table.
Show Attributes for <view name>	Open the list of attributes for the view. This option is available when a screen is backed by a view.

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	Description
Configure	Open the properties for this table.
Remove this item from the Diagram	Remove the selected item(s) from the diagram.
Show many to one relations
Show one to many relations
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	Expand the table to show all the attributes
Parmanently Delete	Delete the selected item(s) from the ERD and from everywhere it is used.

Attribute Pop-up Menu

Option	Description
Make Primary Key
Make Foreign Key
Add New Stream Attribute
Delete Attribute