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.. _erd_tool:
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`ERD Tool` :index:
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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.
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* Drag and drop tables from object explorer to the diagram.
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.. image :: images/erd_tool.png
:alt: ERD tool window
:align: center
You can open multiple copies of the ERD tool in individual tabs simultaneously. To close a copy of the ERD tool, click the *X* in the upper-right hand corner of the tab bar.
Toolbar
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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.
.. image :: images/erd_tool_toolbar.png
:alt: ERD tool toolbar
:align: center
Hover over an icon on Toolbar to display a tooltip that describes the icon's functionality.
File Options
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.. table ::
:class: longtable
:widths: 1 4 1
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| Icon | Behavior | Shortcut |
+======================+===================================================================================================+================+
| *Open File* | Click the *Open File* icon to load a previously saved diagram. | Ctrl + O |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| *Save* | Click the *Save* icon to perform a quick-save of a previously saved diagram, or to save the | Ctrl + S |
| | diagram to a file. | |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| *Save as* | Click the *Save As* to open a new browser dialog and specify a new location to save the diagram. | Ctrl + Shift + |
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| | You need to click the down arrow beside the save button to see *Save As* . | S |
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+----------------------+---------------------------------------------------------------------------------------------------+----------------+
Export Options
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.. table ::
:class: longtable
:widths: 1 4 1
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| Icon | Behavior | Shortcut |
+======================+===================================================================================================+================+
| *Generate SQL* | Click the *Generate SQL* icon to generate the DDL SQL for the diagram and open a query tool | Option + Ctrl +|
| | with the generated SQL ready for execution. | S |
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| | 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. | |
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+----------------------+---------------------------------------------------------------------------------------------------+----------------+
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| *Download image* | Click the *Download image* icon to save the ERD diagram in a image formate | Option + Ctrl +|
| | | I |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
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Editing Options
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.. table ::
:class: longtable
:widths: 1 4 1
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| Icon | Behavior | Shortcut |
+======================+===================================================================================================+================+
| *Add table* | Click this button to add a new table to the diagram. On clicking, this will open a table dialog | Option/Alt + |
| | where you can put the table details. | Ctrl + A |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| *Edit table* | Click this button to edit a table on the diagram. On clicking, this will open a table dialog | Option/Alt + |
| | where you can change table details. This will enable when a table is selected. | Ctrl + E |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| *Clone table* | Click this button to clone the complete table structure, name it with a auto generated name and | Option/Alt + |
| | put it in the diagram. | 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 | Option/Alt + |
| | this button to drop it. | Ctrl + D |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
Table Relationship Options
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.. table ::
:class: longtable
:widths: 1 4 1
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| Icon | Behavior | Shortcut |
+======================+===================================================================================================+================+
| *1M* | Click this button to open a one-to-many relationship dialog to add a relationship between the | Option/Alt + |
| | two tables. The selected table becomes the referencing table and will have the *many* endpoint of | Ctrl + O |
| | the link. | |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| *MM* | Click this button to open a many-to-many relationship dialog to add a relationship between the | Option/Alt + |
| | two tables. This option will create a new table based on the selected columns for the two relating| Ctrl + M |
| | tables and link them. | |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
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Node Color Options
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.. table ::
:class: longtable
:widths: 1 5
+----------------------+----------------------------------------------------------------------------------------------------------+
| Icon | Behavior |
+======================+==========================================================================================================+
| *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. |
+----------------------+----------------------------------------------------------------------------------------------------------+
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Utility Options
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.. table ::
:class: longtable
:widths: 1 4 1
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+-------------------------+------------------------------------------------------------------------------------------------+----------------+
| Icon | Behavior | Shortcut |
+=========================+================================================================================================+================+
| *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 | Option/Alt + |
| | column details. | Shift + D |
+-------------------------+------------------------------------------------------------------------------------------------+----------------+
| *Cardinality Notation* | Change the cardinality notation format used to present relationship links. Options available | |
| | are - Crow's Foot Notation and Chen Notation. | |
+-------------------------+------------------------------------------------------------------------------------------------+----------------+
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Zoom Options
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.. table ::
:class: longtable
:widths: 1 4 1
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
| Icon | Behavior | Shortcut |
+======================+===================================================================================================+================+
| *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 + "-" |
+----------------------+---------------------------------------------------------------------------------------------------+----------------+
Table Dialog
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.. image :: images/erd_table_dialog.png
:alt: ERD tool table dialog
:align: center
The table dialog allows you to:
* Change the table structure details.
* It can be used edit an existing table or add a new one.
* Refer :ref: `table dialog <table_dialog>` for information on different fields.
Table Node
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.. image :: images/erd_table_node.png
:alt: ERD tool table node
:align: center
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 :ref: `table dialog <table_dialog>` for information on different fields.
The One to Many Link Dialog
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.. image :: images/erd_1m_dialog.png
:alt: ERD tool 1M dialog
:align: center
The one to many link dialog allows you to:
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* Add a foreign key relationship between two tables.
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* *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
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.. image :: images/erd_mm_dialog.png
:alt: ERD tool MM dialog
:align: center
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
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.. image :: images/erd_table_link.png
:alt: ERD tool table link
:align: center
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
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.. image :: images/erd_table_note.png
:alt: ERD tool table note
:align: center
* 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.
