A record-based logical model is a way of organizing and storing data in a database system. In this model, data is structured into records, which consist of fields or attributes that hold specific pieces of information. Each record is unique and identifiable by a primary key, allowing for efficient retrieval and manipulation of data. Examples of record-based logical models include relational databases and XML databases.
-> A record based data model is used to specify the overall logical structure of the database.-> In this model the database consists of a no. of fixed formats of different types.-> Each record type defines a fixed no. of fields having a fixed length.-> There are 3 principle types of record based data model. They are :1. Hierarchical data model.2. Network data model.3. Relational data model.
In record design we distinguish between logical and physical records. LOGICAL RECORDS: A logical record maintains a logical relationship among all the data items in the records.It is the way the programmer or user sees the data.IN CONTRAST, A PHYSICAL RECORD is the way data are recorded on a storage medium.The programmer doesnt know about the physical map on the disk.The software presents the logical record in the required sequence.The capability is unique to the data base design. This question is answered by Silpa Sonali Sahoo.I request all the User if you can give some extra knoweldge/idea based on the discussed topic then you are most welcome.
Master Boot record
1. Why is important to develop a logical model of proposed system before generating a technical architecture
* Physical file (PF) contains the data and have only one record format. Logical file (LF) is a view of the physical file which does not contain any data may be based on one physical file or more then one physical file. Logical file can have more then one record format. Logical can be non join or join logical file. Performance becomes better if you use the logical file in the program.
An organization in which all records are a fixed logical record length and records are extracted through the specification of their relative record number.
Networking layer of the OSI model
A data model is a collection of concepts that can be used to describe the structure of a database and provides the necessary means to achieve this abstraction whereas structure of a database means the data types,relationships and constraints that should hold on the data. Data model are divided into three different groups they are 1)object based logical model 2)record based logical models 3)physical models Types: Entity-Relationship (E-R) Data Model Object-Oriented Data Model Physical Data Model functional data model
The physical connection is layer 1 of the OSI model, and is the medium through which the data is transfered. i.e., cables The logical connection is layer 3 of the OSI model, and is the network portion. Using the Internetwork Protocol (IP), each host is assigned a 32 bit IP address. e.g. 192.168.1.1
The WRITE statement in a programming language like COBOL will always place a record in the next logical position for sequential files. This means that the next record will be written at the end of the file, regardless of the physical location of the record.
1990 Dycam Model 1