What is the difference between logical data model and conceptual data model

Question

User · Answer

In this table you can see the difference between each model    See http   www 1keydata com datawarehousing data-modeling-levels html for more information and some data model examples

User · Answer

Most answers here are strictly related to notations and syntax of the data models at different levels of abstraction  The key difference has not been mentioned by anyone  Conceptual models surface concepts  Concepts relate to other concepts in a different way that an Entity relates to another Entity at the Logical level of abstraction  Concepts are closer to Types  Usually at Conceptual level you display Types of things  this does not mean you must use the term  type  in your naming convention  and relationships between such types  Therefore  the existence of many-to-many relationships is not the rule but rather the consequence of the relationships between type-wise elements  In Logical Models Entities represent one instance of that thing in the real world  In Conceptual models it is not expected the description of an instance of an Entity and their relationships but rather the description of the  type  or  class  of that particular Entity  Examples  - Vehicles have Wheels and Wheels are used in Vehicles  At Conceptual level this is a many-to-many relationship - A particular Vehicle  a car by instance   with one specific registration number have 5 wheels and each particular wheel  each one with a serial number is related to only that particular car  At Logical level this is a one-to-many relationship   Conceptual covers  types classes   Logical covers  instances    I would add another comment about databases  I agree with one of the colleagues who commented above that Conceptual and Logical models have absolutely nothing about databases  Conceptual and Logical models describe the real world from a data perspective using notations such as ER or UML  Database vendors  smartly  designed their products to follow the same philosophy used to logically model the World and them created Relational Databases  making everyone s lifes easier  You can describe your organisation s data landscape at all the levels using Conceptual and Logical model and never use a relational database   Well I guess this is my 2 cents

User · Answer

Logical Database Model  Logical database modeling is required for compiling business requirements and representing the requirements as a model  It is mainly associated with the gathering of business needs rather than the database design  The information that needs to be gathered is about organizational units  business entities  and business processes   Once the information is compiled  reports and diagrams are made  including these   ERD   Entity relationship diagram shows the relationship between different categories of data and shows the different categories of data required for the development of a database  Business process diagram   It shows the activities of individuals within the company  It shows how the data moves within the organization based on which application interface can be designed  Feedback documentation by users   Logical database models basically determine if all the requirements of the business have been gathered  It is reviewed by developers  management  and finally the end users to see if more information needs to be gathered before physical modeling starts   Physical Database Model Physical database modeling deals with designing the actual database based on the requirements gathered during logical database modeling  All the information gathered is converted into relational models and business models  During physical modeling  objects are defined at a level called a schema level  A schema is considered a group of objects which are related to each other in a database  Tables and columns are made according to the information provided during logical modeling  Primary keys  unique keys  and foreign keys are defined in order to provide constraints  Indexes and snapshots are defined  Data can be summarized  and users are provided with an alternative perspective once the tables have been created   Physical database modeling depends upon the software already being used in the organization  It is software specific  Physical modeling includes   Server model diagram   It includes tables and columns and different relationships that exist within a database  Database design documentation  Feedback documentation of users   Summary   1 Logical database modeling is mainly for gathering information about business needs and does not involve designing a database  whereas physical database modeling is mainly required for actual designing of the database  2 Logical database modeling does not include indexes and constraints  the logical database model for an application can be used across various database software and implementations  whereas physical database modeling is software and hardware specific and has indexes and constraints  3 Logical database modeling includes  ERD  business process diagrams  and user feedback documentation  whereas physical database modeling includes  server model diagram  database design documentation  and user feedback documentation   Read more  Difference Between Logical and Physical Database Model   Difference Between   Logical vs Physical Database Model http   www differencebetween net technology software-technology difference-between-logical-and-physical-database-model  ixzz3AxPVhTlg

User · Answer

I need to produce both a logical model and a conceptual model  All the explanations here are really vague  The link posted above just shows the difference being that a conceptual model is a logical model without fields  Ok fine  I don t mention the name of the database  It appears to be totally redundant    I really don t know what  semantic  means  can someone explain what I would do differently using  english  and possibly post a link to better examples than a picture that shows one picture that has fields and one that does not  The buzzwords are all well and good  but its so vague its not useful to practically implement    do I do anything other than take my logical model  which is basically my physical model reversed engineered out of the DB  click a button in said tools and the images look a little different and then take off the data types    From what i can practically see  and without buzzwords   physical model  actually tables  The little pictures have data types in them and named pk fk constraints Logical Model  click the little button my tool  using Oracles SQL Developer Data Modeller  I dont have an erwin license and 2010 visio no longer reverse engineers out of the DB   and then the images on the screen change slightly  The data types are gone and the names of the constraints are gone  then the colors of the table representations changes to purple  so now I call them entities     ok  so what would my Conceptual model look like other then  exact same thing as my logical model minus the fields  I would think there is more to it than this  Reciting that its a  semantic  representation of data sounds real nice and fancy  but doesn t make sense to someone who has not made one of these before

User · Answer

First of all  a data model is an abstraction tool and a database model  or scheme diagramm  is a modeling result   Conceptual data model is DBMS-independent and covers functional domain design area  The most known conceptual data model is  Entity-Relationship   Normally  you can reuse the conceptual scheme to produce different logical schemes not only relational   Logical data model is intended to be implemented by some DBMS and corresponds mostly to the conceptual level of ANSI SPARC architecture  proposed in 1975   this point gives some collisions of terminology  Zachman Framework tried to resolve this kind of collision ten years later introducing conceptual  logical and physical models   There are many logical data models  and the most known is relational one   So main differences of conceptual data model are the focusing on the domain and DBMS-independence whereas logical data model is the most abstract level of concrete DBMS you plan to use  Note that contemporary DBMS support several logical models at the same time   You can also have a look to my book and to the article for more details

User · Answer

In the conceptual data model you worry only about the high level design - what tables should exist and the connections between them  In this phase you recognize entities in your model and the relationships between them   The logical model comes after the conceptual modeling when you explicitly define what the columns in each table are  While writing the logical model  you might also take into consideration the actual database system you re designing for  but only if it affects the design  i e   if there are no triggers you might want to remove some redundancy column etc    There is also physical model which elaborates on the logical model and assigns each column with it s type length etc   Here is a good table and picture that describes each of the three levels    ---------------------- ------------ --------- ----------    Feature                Conceptual   Logical   Physical     ---------------------- ------------ --------- ----------    Entity Names           X            X                      Entity Relationships   X            X                      Attributes                          X                      Primary Keys                        X         X            Foreign Keys                        X         X            Table Names                                   X            Column Names                                  X            Column Data Types                             X           ---------------------- ------------ --------- ----------

User · Answer

These terms are unfortunately overloaded with several possible definitions  According to the ANSI-SPARC  three schema  model for instance  the Conceptual Schema or Conceptual Model consists of the set of objects in a database  tables  views  etc  in contrast to the External Schema which are the objects that users see   In the data management professions and especially among data modellers   architects  the term Conceptual Model is frequently used to mean a semantic model whereas the term Logical Model is used to mean a preliminary or virtual database design  This is probably the usage you are most likely to come across in the workplace   In academic usage and when describing DBMS architectures however  the Logical level means the database objects  tables  views  tables  keys  constraints  etc   as distinct from the Physical level  files  indexes  storage   To confuse things further  in the workplace the term Physical model is often used to mean the design as implemented or planned for implementation in an actual database  That may include both  physical  and  logical  level constructs  both tables and indexes for example    When you come across any of these terms you really need to seek clarification on what is being described unless the context makes it obvious   For a discussion of these differences  check out Data Modelling Essentials by Simsion and Witt for example

User · Answer

This is an old question and maybe this comes way too late  but I don t see one very important aspect necessary to answering the question  That is  the TARGET audience for the data model  The Conceptual Data Model is the model generated from business analysis  from interviews with the BUSINESS about their data  It is not so much  high level  as it is the business s understanding of their data  business rules captured in the relationships between  candidate  entities  At this point  you are capturing the things of importance to the business  Employee  Customer  Contract  Account  etc   and the relationships between them  The final Conceptual Data Model may be somewhat abstract -- for instance  treating Individuals and Organizations entering into a contract as subtypes of a  Party   Contractors and Permanent Employees as subtypes of an Employee  even Employees and Customers subtypes of  Person  -- but it is a document that a data modeler develops from discussions with the business SMEs and presents to the business for validation   The Logical Data Model is not just  more detail  -- where useful and important  a Conceptual Data Model may well have attributes included -- it is the ARCHITECTURE document  the model that is presented to the software analysts engineers to explain and specify the data requirements  It will resolve many-to-many relationships to association tables and will define all attributes  with examples and constraints  so that code can be written against the architecture    The Physical model is that Logical Model generated specifically for a particular environment  such as SQL Server or Teradata or Oracle or whatever  It will have keys  indexes  partitions  or whatever is needed to implement  based on sizing  access frequency  security constraints  etc     So  if you are being asked to develop a Conceptual Data Model  you are being asked to design the solution  or part of it  from scratch  getting your information from the business   There s more to it  but I hope that answers the question

User · Answer

Conceptual Schema - covers entities and relationships   Should be created first  Contrary to some of the other answers  tables are not defined here   For example a  many to many  table is not included in a conceptual data model but is defined as a  many to many  relationship between entities    Logical Schema - Covers tables  attributes  keys  mandatory role constraints  and referential integrity with no regards to the physical implementation  Things like indexes are not defined   attribute types should be kept logical  e g  text instead of varchar2  Should be created based on the conceptual schema

User · Answer

logical data model  A logical data model describes the data in as much detail as possible  without regard to how they will be physical implemented in the database  Features of a logical data model include             Includes all entities and relationships among them             All attributes for each entity are specified             The primary key for each entity is specified             Foreign keys  keys identifying the relationship between different entities  are specified             Normalization occurs at this level   conceptual data model  A conceptual data model identifies the highest-level relationships between the different entities  Features of conceptual data model include             Includes the important entities and the relationships among them             No attribute is specified             No primary key is specified

[database] What is the difference between logical data model and conceptual data model?

Examples related to database

Examples related to database-design