What is a relational database? | Complete guide
Relational databases are the most popular and commonly used digital databases. In this article, we discuss relational database, how it works, examples, differences between relational and non-relational databases, etc.
What is a relational database?
A relational database is a model-based data collection that organizes data points that are related to each other. The term was initially presented by an English computer scientist Edgar Frank “Ted” Codd at the IBM Research Lab in 1970.
Relational databases organize valuable information or data into tables that can be linked to multiple other tables based on data common to each other. It allows users to create a new dataset from data from one or more related tables using a single query.
Data structures used by relational databases include tables, indexes, and views. The main components of a relational database are tables, columns, and rows.
A relational database management system (RDBMS) is used to maintain the relational databases. Additionally, many RDBMSs support Structured Query Language (SQL) for queries and management.
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How does a relational database work?
Relational databases work by linking information or data from multiple tables linked via “keys”. Keys are unique identifiers that can be assigned to a row of unique data contained in a table. This unique identifier is known as the “primary key” and can include identifiers, serial numbers, usernames, etc.
The primary key can be included in a record of another table when the record has a relationship to the primary record of the main table. If a primary key is added to the record in another table, it is called a “foreign key”. The connection between primary and foreign keys creates a relationship between sets of data in multiple tables.
Examples of relational databases
The most popular standard relational databases include:
- Microsoft SQL Server
- IBM DB2
The most commonly used cloud-based relational databases include:
- Oracle Cloud
- AWS Relational Database Service
- Google Cloud SQL
- IBM Db2 in the cloud
- SQL Azure
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Relational vs. non-relational database: what’s the difference?
Relational databases are developed for structured data that conforms to a predefined data model. Conversely, non-relational databases are used for unstructured data. For example, a relational database would be used for sales tracking, invoicing or asset management.
Non-relational databases tend to have more specific use cases. An example of a non-relational database use case would be working with big data that requires highly optimized search indexes.
the differences between relational and non-relational databases are given below.
|Relational database||Non-relational database|
|Data type||Structure||Usually unstructured|
|Query language||SQL||SQL and others|
|Data quantities||Big||Varies, some may support Big Data|
|Best suited to||Heavy and structured data transactions||Specialized use cases|
|Examples||Oracle, MySQL, PostgreSQL||MongoDB, Dynamo DB, Redis|
Relational database model
Relational database models represent a database as a set of relationships and sets of relationships. Relationships are the array of associated data values, where each row represents a collection of data values and denotes a real-world relationship or entity. The table and its columns are used to interpret the values in each row.
In the relational database model, information or data is stored as tables. Note that the physical storage of associated data is independent of how it is logically organized.
Types of relationships between entities
The association between two entities is called a relationship. There are three types of relationships between two entities in the design of relational databases.
- One-to-one relationship
- One-to-many or many-to-one relationship
- Many-to-many relationship
In the One by one relationship, each record in Table X relates to one and only one record in Table Y, and each record in Table Y relates to one and only one record in Table X. For example, the relationship between an employee and his laptop company .
In the One-to-many Where Many-to-One relationship, each record in table X relates to many records in table Y, and each record in table Y relates to many records in table X. For example, the relationships between a company and its stock of laptops for employees.
In the Many to many relation, many records in table X relate to many records in table Y, and many records in table Y relate to many records in table X. For example, the relationships between laptops in l company and their installed applications.
Relational databases provide users and businesses with a better understanding of the relationships between available information and data. Over the years, relational databases have successfully managed large amounts of data and have become better, faster, stronger, and easier to use. This is why they remain the most popular type of database.
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