ERD Tool
The Entity-Relationship Diagram (ERD) tool is a database design tool that provides a graphical representation of database tables, columns, and inter-relationships. ERD can give sufficient information for the database administrator to follow when developing and maintaining the database. The ERD Tool allows you to:
Design and visualize the database tables and their relationships.
Add notes to the diagram.
Auto-align the tables and links for cleaner visualization.
Save the diagram and open it later to continue working on it.
Generate ready to run SQL from the database design.
Generate the database diagram for an existing database.
Drag and drop tables from object explorer to the diagram.
You can open multiple copies of the ERD tool in individual tabs simultaneously.
You can also generate an ERD from a database, schema or a table.
The ERD for database will fetch all the tables from all the schemas of the database and plot them with foreign key links.
The ERD for schema will fetch all the tables from a schema and plot them with foreign key links. If any table refers to a table in another
schema, then that link/foreign key will be removed.
The ERD for table will fetch all the tables linked directly or indirectly to mentioned table. You can change the depth of traversal from
Preferences
.
Toolbar
The
ERD Tool
toolbar uses context-sensitive icons that provide shortcuts to frequently performed tasks. The option is enabled for the highlighted icon and is disabled for the grayed-out icon.
Hover over an icon on Toolbar to display a tooltip that describes the icon’s functionality.
File Options
Click the
Save
icon to perform a quick-save of a previously saved diagram, or to save the
diagram to a file.
Cmd/Ctrl + S
Save as
Click the
Save As
to open a new browser dialog and specify a new location to save the diagram.
You need to click the down arrow beside the save button to see
Save As
.
Ctrl + Shift +
Generate SQL
Click the
Generate SQL
icon to generate the DDL SQL for the diagram and open a query tool
with the generated SQL ready for execution.
You can select the option
With DROP Table
if you wish to have DROP Table DDL statements before
each CREATE Table DDL. You can see the option by clicking the down arrow beside the SQL button.
Option/Alt +
Ctrl + S
Download image
Click the
Download image
icon to save the ERD diagram in a image formate
Option/Alt +
Ctrl + I
Add table
Click this button to add a new table to the diagram. On clicking, this will open a table dialog
where you can put the table details.
Option/Alt +
Ctrl + A
Edit table
Click this button to edit a table on the diagram. On clicking, this will open a table dialog
where you can change table details. This will enable when a table is selected.
Option/Alt +
Ctrl + E
Clone table
Click this button to clone the complete table structure, name it with a auto generated name and
put it in the diagram.
Option/Alt +
Ctrl + C
Drop table/link
You can drop a table or link using this button. You need to select a table or link and click on
this button to drop it.
Option/Alt +
Ctrl + D
Click this button to open a one-to-many relationship dialog to add a relationship between the
two tables. The selected table becomes the referencing table and will have the
many
endpoint of
the link.
Option/Alt +
Ctrl + O
Click this button to open a many-to-many relationship dialog to add a relationship between the
two tables. This option will create a new table based on the selected columns for the two relating
tables and link them.
Option/Alt +
Ctrl + M
Fill Color
Use Fill Color to change the background color of a table node. This is helpful if you want to
identify a of group tables. Once set, all the newly added tables will take the same color.
Text Color
Use Text Color to change the text color of a table node based on the fill color to make text
easily readable.
Add/Edit note
Click this button to make notes on tables nodes while designing the database.
Option/Alt +
Ctrl + N
Auto align
Click this button to auto align all tables and links to make it look more cleaner.
Option/Alt +
Ctrl + L
Show details
Click this button to toggle the column details visibility. It allows you to show few or more
column details.
Option/Alt +
Shift + D
Cardinality Notation
Change the cardinality notation format used to present relationship links. Options available
are - Crow’s Foot Notation and Chen Notation.
Zoom to fit
Click this button to zoom in/out automatically and fit all the tables to the view.
Option/Alt +
Shift + F
Zoom in
Click this button to zoom in the diagram.
Option/Alt +
Shift + “+”
Zoom out
Click this button to zoom out the diagram.
Option/Alt +
Shift + “-”
Change the table structure details.
It can be used edit an existing table or add a new one.
Refer
table dialog
for information on different fields.
Table Node
The table node shows table details in a graphical representation:
The top bar has a
details toggle button
that is used to toggle column details visibility. There is also a
note button
that is visible only if there is some note added. you can click on this button to quickly change the note.
The first row shows the schema name of the table. Eg.
public
in above image.
The second row shows the table name. Eg.
users
in above image.
All other rows below the table name are the columns of the table along with data type. If the column is a primary key then it will have lock key icon eg. id is the primary key in above image. Otherwise, it will have column icon.
you can click on the node and drag to move on the canvas.
Upon double click on the table node or by clicking the edit button from the toolbar, the table dialog opens where you can change the table details. Refer
table dialog
for information on different fields.
The One to Many Link Dialog
The one to many link dialog allows you to:
Add a foreign key relationship between two tables.
Local Table
is the table that references a table and has the
many
end point.
Local Column
the column that references.
Referenced Table
is the table that is being referred and has the
one
end point.
Referenced Column
the column that is being referred.
The Many to Many Link Dialog
The many to many link dialog allows you to:
Add a many to many relationship between two tables.
It creates a relationship tables having columns derived from the two tables and link them to the tables.
Left Table
is the first table that is to be linked. It will receive the
one
endpoint of the link with the new relation table.
Left Column
the column of the first table, that will always be a primary key.
Right Table
is the second table that is to be linked. It will receive the
one
endpoint of the link with the new relation table.
Right Column
the column of the second table, that will always be a primary key.
The Table Link
The table link shows relationship between tables:
The single line endpoint of the link shows the column that is being referred.
The three line endpoint of the link shows the column that refers.
If one of the columns that is being referred or that refers is removed from the table then the link will get dropped.
you can click on the link and drag to move on the canvas.
The Table Notes
You can use the notes popup to mark some notes while designing the database.
You open the pop-up using the toolbar note button.
If some note is added to a table then it will have notes button on the table node. You can click on the button to check/update notes.
