Relational model

Desmond Akachukwu
29 Mar, 2022
2

  Relational model is a simple and elegant database with a collection of one or more relations where each record is a table with rows and columns.

  A relation consist of a relation schema and relation instance. The istance is the table and the schema describes a column head for the table. A software called RELATIONAL DATABASE MANAGEMENT SYSTEM is used to handle a relational database.
 
  RBDMS is the basic for SQL (Structured Query Language) and for all the modern day database systems like MySQL server, FOXBase, Oracle, SyBase and MS access

Terms in relational data model

The following are some popular terms associated with relational data model;

Table;

This is a collection of related data entries arranged in rows and columns. Data in RDBMS is stored in tables. The below table is an example of relational table called customer table.
Customer table
Customer ID Name Address Age Net pay
1 Daramola Ikorodu 20 15,000
2 Kevwe Oyingbo 25 25000
3 Ejiro Island 40 100,000
4 Etim Alogemeji 36 80,000
5 Idani Tabontabon 23 5,000

Field

This is an item of information in a table that is designed to Maintain a specific information about every record.

Record

This is a collection of related fields. It is the individual entries that exist in a table

Column

This is the vertical entry in a table associated with a specified field.

Null Value

A null value in a table indicate that the value of a field is blank. A field with a null value is a field with no value. It is different from 0 and spaces.

Creating and modifying a relation using SQL

A database relation or table is a predefined row and column format for storing information in a database. To create and modify tables in a relational database, a Structured Query Language is used.

SQL is a computer language used for storing, manipulating and retrieving data stored in a relational database. It can be used for database creation, deletion, selection, alteration etc. It has different versions which are are RDBMS
  1. MYSQl
  2. MS access
  3. Oracle
  4. Java
  5. SyBase
  6. SQL server etc
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2 Comments
  • Unknown
    Unknown March 29, 2022 at 9:51 AM

    Very much helpful

    Reply
  • Unknown
    Unknown March 29, 2022 at 9:51 AM

    Love this

    Reply
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