Define database model logic
A logical data model ( LDM ) in systems engineering is a representation of an organization's data , organized in terms of entities and relationships, and is independent of any particular technology data management .Logical data models represent the abstract structure of a domain of information. Often are schematic in nature and are most commonly used in business processes that try to capture the things of importance to an organization and how they relate to each other . Once validated and approved , the logical data model can be the basis of a physical model data and information for the design of a database .
Logical data models should be based on the structures identified in a conceptual model of previous data , since this describes the semantics of the context information that the logic model should also reflect . However, since the expected logical data model application on a specific computer system , the contents of the logical data model is adjusted to achieve certain efficiencies .
The term " Logical Data Model " is sometimes used as a synonym for " domain model " or as an alternative to the model domain . While the two concepts are closely related, and whose objectives overlap , a domain model is more focused on the capture of the concepts in the problem domain rather than the structure of the data associated with that domain.
Database design is the production process of a data model from a detailed database . This logical data model contains all the necessary options logical and physical design and physical storage parameters needed to generate a design in a Data Definition Language , which can then be used to create a database. A fully attributed data model contains detailed attributes for each entity.
Database design term may be used to describe many different parts of the design of a system of global database . Principally, and most correctly, it can be thought of as the logical design of the base data structures used to store data
Reasons for building a logical data model
Help the common understanding of the data elements and business requirements
Provides the basis for designing a database
Facilitates prevent data redundancy and prevent data inconsistency and business transaction
Facilitates data re - use and exchange of
Decreases development and maintenance time and cost
Confirms logical process model and helps impact analysis .
Logically structured data
Once you have determined the relationships and dependencies between different pieces of information , it is possible to arrange the data in a logical structure that can be mapped to the storage objects supported by the management system database. In the case of relational database storage objects are tables that store data in rows and columns.
Each table may represent one application of either a logical object or a relation of joining one or more instances of one or more logical objects . Relationships between tables can then be stored as links connecting child tables with parents. Since complex logical relationships are themselves tables they probably have links to more than one parent .
In an object database storage objects correspond directly to the objects used by the language of object-oriented programming used to write applications that will manage and access data . Relationships can be defined as attributes of the object classes involved or as methods that operate on the object classes .
The design process
The design process consists of the following steps [3] :
Determine the purpose of the database - This helps you prepare for the remaining stages .
Find and organize the information required - Gather all the types of information we might want to record in the database , such as the product name and order number .
Divide the information into tables - Divide your information items into major entities or subjects , such as products or orders. Every issue becomes a table.
Turn information items into columns - Decide what information you want to store in each table. Each item becomes a field, and is displayed as a column in the table. For example , an Employees table might include fields such as Last Name and Hire Date .
Specifying Primary Keys - Select the primary key of each table. The primary key is a column that is used to uniquely identify each row. An example might be Product ID or Order ID .
Set table relationships - Look at each table and decide how the data in one table relates to data in other tables. Add fields to tables or create new tables to clarify the relationships , as needed.
Refine your design - Analyze the design errors . Create the tables and add some sample data records . See if you can get the results you want from your tables. Adjustments in design as needed .
Apply the normalization rules - Apply the data normalization rules to see if the tables are structured correctly . Make adjustments to the tables
How to create logical database
Now , let's talk about how we can create a logical database backup and database management logic.
Before you create the logical database perform the following checks to ensure that the primary database qualify for the logical database backup .
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