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Toad Data Modeler 7.0 - User Guide

Introduction User Interface Models and Model Objects
Physical Data Model
Entity Relationship Diagram Objects Basic Database Design Advanced Database Design
Universal Data Model Logical Data Model Working with Model Objects
Features and Tools
Application Variables Export/Import DDL Script Generation Graphics Model Actions Print Create New Project Reports Reverse Engineering Scripting and Customization About Templates Tips and Tricks Toad for Oracle Integration Toad Intelligence Central (TIC) Integration Tools Version Control
Options and Configuration Databases
Amazon Redshift 1.0 IBM DB2 LUW 9.5 IBM DB2 LUW 9.7 IBM DB2 LUW 10.1 IBM DB2 LUW 10.5 IBM DB2 LUW 11.1 IBM DB2 z/OS 10 IBM DB2 z/OS 11 Greenplum 4.1 Greenplum 4.2 Ingres 9.3 Ingres 10.0 EDB Postgres Advanced Server 10 Microsoft Access 2007/2010 Microsoft Azure SQL Database V12 Microsoft SQL Server 2005 Microsoft SQL Server 2008 Microsoft SQL Server 2012 Microsoft SQL Server 2014 Microsoft SQL Server 2016 Microsoft SQL Server 2017 MySQL 5.0 MySQL 5.1 MySQL 5.5 MySQL 5.6 MySQL 5.7 MySQL 8.0 Oracle 10g Oracle 11g Release 1 Oracle 11g Release 2 Oracle 12c Release 1 Oracle 12c Release 2 Oracle 18c Specifics - Oracle 12c Release 2 PostgreSQL 9.0 PostgreSQL 9.1 PostgreSQL 9.2 PostgreSQL 9.3 PostgreSQL 9.4 PostgreSQL 9.5 PostgreSQL 10 SQLite 3.7 Sybase ASE 15.5 Sybase ASE 15.7 SAP ASE 16.0 Sybase IQ 15.2 Sybase SQL Anywhere 11 SAP SQL Anywhere 17 Teradata 13 Vertica Database 8.0
Copyright Legal Notices

Inheritance

Toad Data Modeler allows you to design and maintain a logical model giving a complete picture of the business area. Logical model is independent of the database platform and is much simpler than physical model. It uses objects such as inheritance, valid values or M:N relationships. From the Logical ER (LER) diagram, you can build a Physical ER (PER) diagram of the selected database platform (LER to PER conversion).

Note:

  • This topic contains information on objects and functions that are specific for logical modeling. General information and other features applicable in Logical model as well as in Physical model are contained and described in other sections of this Help file. See e.g. the "Model Objects" chapter, "Model Explorer" topic etc.
  • See the sample logical model Employee that is included in the installation package for Toad Data Modeler. Default location is: C:\Program Files\Quest Software\Toad Data Modeler\Samples.

To create a logical model

Select File | New | Model |Logical Data Model tab.

Benefits of Logical Data Model

Logical Data Model allows you to model inheritances in entity relationship diagrams. Universal Data Model and Physical Data Model do not support this feature.

Specifics of Logical Data Model

  • There are three methods how inheritance can be resolved when converting to physical model.
  • Attributes do not migrate to child entities.
  • It is not possible to define database specific items in Logical Model, for example sequences/autoincrements etc.
  • You can define Valid Values in logical model (will be converted to physical model).

Benefits of Super and Sub Types

In Logical Model you can define database structure in various ways. See the pictures below. Both of them show a structure modeled in Logical Model and both the models will result in the identical output when converted to Physical Model. The difference is that Model A uses Super and Sub Types while Model B doesn't use inheritance at all.

Model A - Utilizing Super and Sub Types

Model B - Lacking Super and Sub Types

This example shows:

  1. That you can create logical models in different ways and achieve the same result after conversion to physical model.
  2. That you can be more productive when using inheritance. For example, you only need to change the Last Name attribute once in the first model. Without using inheritance in model B, you have to change it four times.
  3. How much “readable” the first model is compared to the second one.
  4. How important is to select appropriate inheritance resolution when converting your logical model to physical.
  5. That creating logical models without inheritance has minimal benefits compared to using inheritance.

Disadvantage

The main disadvantage of logical modeling is that direct synchronization with existing database is not possible. Only physical models of specific database platforms and versions may be synchronized with an existing database. Therefore, if you want to synchronize your logical model, you need to convert it to the physical model first.

Create Inheritances

  1. Click on the toolbar (also CTRL+I)
  1. Move your mouse cursor over the work area and click the parent entity and then the target entity (child).

TIP:

  • While creating an inheritance, you can add handle points at the same time. Click the parent entity and then click the work area as many times as many handle points you want to create. Finally click the child entity.
  • Create several Children of the existing inheritance:
  1. Click the Inheritance icon on the toolbar.
  2. Click the inheritance in the model.
  3. Click another entity in the model.

Edit Inheritances

  • Double-click the inheritance on the Workspace.

or

  • Edit the inheritance in Model Explorer | Inheritances folder | double-click the selected inheritance (or right-click | Edit).

Option Description

Object Navigator Dropdown Menu

All inheritances in your model are listed here. Use it to switch between multiple objects and edit them easily.

General Tab

Description

Caption

Logical name of inheritance

Name

Physical name of inheritance

Parent

Name of the parent entity

Logical Only

Select this checkbox to not convert the inheritance during LER to PER conversion.

Exclusive

Definition of exclusive inheritance.

For exclusive inheritances, Toad Data Modeler generates triggers that will perform a check whether a correct record in siblings exists or not, and decide whether a record can be added to table or not etc.  

Exclusive inheritances are displayed with cross in the middle of the graphics:

Standard inheritances don't have the cross inside the graphics:

Complete

Logical information only. The information says that all records must be complete.

Generation Tab

On this tab, select how do you want to resolve the inheritance during conversion from LER to PER. Inheritance

Descendents Tab

Description

Name

Name of descendent

Discriminator Valid Value

Valid values of Discriminator

Edit Discriminator

Opens the Valid Values dialog for the selected Discriminator.

To Do Tab

You can enter To Do tasks related to the object here.

Note: To display all To Do tasks, select To Do from Model menu.

Description Tab You can enter the object description here.

Conversion to Physical Model

Toad Data Modeler allows you to design and maintain a logical model giving a complete picture of the business area. Logical model is independent of the database platform and is much simpler than physical model. It uses objects such as inheritance, valid values or M:N relationships. From the Logical ER (LER) diagram, you can build a Physical ER (PER) diagram of the selected database platform (LER to PER conversion).

Note:

  • This topic contains information on objects and functions that are specific for logical modeling. General information and other features applicable in Logical model as well as in Physical model are contained and described in other sections of this Help file. See e.g. the "Model Objects" chapter, "Model Explorer" topic etc.
  • See the sample logical model Employee that is included in the installation package for Toad Data Modeler. Default location is: C:\Program Files\Quest Software\Toad Data Modeler\Samples.

To create a logical model

Select File | New | Model |Logical Data Model tab.

Benefits of Logical Data Model

Logical Data Model allows you to model inheritances in entity relationship diagrams. Universal Data Model and Physical Data Model do not support this feature.

Specifics of Logical Data Model

  • There are three methods how inheritance can be resolved when converting to physical model.
  • Attributes do not migrate to child entities.
  • It is not possible to define database specific items in Logical Model, for example sequences/autoincrements etc.
  • You can define Valid Values in logical model (will be converted to physical model).

Benefits of Super and Sub Types

In Logical Model you can define database structure in various ways. See the pictures below. Both of them show a structure modeled in Logical Model and both the models will result in the identical output when converted to Physical Model. The difference is that Model A uses Super and Sub Types while Model B doesn't use inheritance at all.

Model A - Utilizing Super and Sub Types

Model B - Lacking Super and Sub Types

This example shows:

  1. That you can create logical models in different ways and achieve the same result after conversion to physical model.
  2. That you can be more productive when using inheritance. For example, you only need to change the Last Name attribute once in the first model. Without using inheritance in model B, you have to change it four times.
  3. How much “readable” the first model is compared to the second one.
  4. How important is to select appropriate inheritance resolution when converting your logical model to physical.
  5. That creating logical models without inheritance has minimal benefits compared to using inheritance.

Disadvantage

The main disadvantage of logical modeling is that direct synchronization with existing database is not possible. Only physical models of specific database platforms and versions may be synchronized with an existing database. Therefore, if you want to synchronize your logical model, you need to convert it to the physical model first.

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