Relational databases are a system for storing and organizing information that has established relationships, which allows for quick access. In this case, data is organized using tabular forms that contain information about their nature. Relational database operating principle, prospects of use and rows and columns in such tables represent pre-established categories of data.
This method of structuring information makes the procedure of accessing it more flexible and faster. It is this circumstance that contributed to the fact that this type of databases has become the most widespread. They support the standard programming language – SQL . This is a popular system for storing and processing information. Within the framework of SQL, built-in languages of relational databases are also used: DDL for tables (used to describe data) and DML for working with data.
Let’s consider the concept of “relational”. This term indicates the presence of connections in information bases. For example, a company’s customer base may include information on each transaction associated with a separate account. Particular attention is paid here to the pre-established relationships between stored data blocks.
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As an example of a relational database, consider the tables used by a small firm to process product orders. The first table form contains customer how to search for groups on telegram information. Here, each record contains information about the customer’s name and address, payment details, contact phone number, etc.
Each data attribute (information element) is ar numbers placed in a separate column of the information base. All columns have their own unique identifier for each row (key). The second table form contains separate records with the identifier of the client who submitted the application, the name of the ordered product, its quantity and characteristics. As we can see, this table does not contain client data (name, phone, address, etc.).
In this case, the database, processing the table form with information about applications, selects data about the product and, using the client’s key, receives information about payment and delivery. After that, warehouse workers find the necessary product, the client receives it and pays for it.
Important components of a relational database
SQL
Structured Query Language (SQL programming language) is the basis of the interface for relational databases. It became an ANSI (United States National Standards Institute) standard in 1986.
Data integrity
Data integrity means ensuring its accuracy, completeness and uniformity. To solve this problem in the context of relational databases, a certain set of tools is used, including primary and foreign keys, as well as the constraints “Not NULL”, “Unique”, “Default” and “Check”.
Data integrity tools address the application of rules of thumb to tabular information and ensure data accuracy and reliability.
Transactions
A transaction in a database is a set of sequential operations that are a single logical task and the application of one or more SQL statements. It is an indivisible action.
ACID Compliance
To ensure the integrity requirement of relational databases, all transactions in them must satisfy the ACID requirements (they must be atomic, uniform, isolated, and reliable).
The first condition is “atomicity”. It specifies that any transaction must be executed in its entirety. If at least one of its elements is not executed, the entire transaction must be cancelled. In accordance with the “uniformity” condition, all elements written to the fields of a relational database by transaction must satisfy a set of rules and restrictions, including integrity, cascades, and triggers.
The isolation condition is important for data consistency control. It is also necessary to ensure the basic independence of all transactions.
Advantages and Disadvantages of Relational Databases
We will consider the main pros and cons taking into account the organizational structure of the relational database.
Modern database models built on the SQL programming language to some extent depart from the logical relational model created by mathematician E. Codd. For example, the founder of the system initially envisaged the need to ensure the uniqueness of each new row.
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As the relational database model has grown in popularity against the backdrop of increasing size and value of stored and processed information, its weaknesses have also begun to emerge. For example, significant difficulties arise with horizontal scaling of such databases. The ability to scale a database horizontally is standard practice when adding a large number of machines to an existing stack.
This helps distribute the load rationally, speed up processing, and increase traffic. Horizontal scaling is often an alternative to vertical scaling, which involves upgrading the hardware of an existing server (usually by adding RAM or a central processor).
When scaling horizontally, it will be difficult to ensure data integrity, since users can only write to one node, and not to all nodes at the same time.
There will likely be a delay between the initial write and the update of other nodes to reflect the changes, resulting in data integrity issues between nodes in the system.
The increase in the number of PCs and the development of the World Wide Web contributed to the fact that in the early nineties large volumes of unstructured data began to appear (e-mails, photos, videos, etc.).
Nevertheless, relational databases remain relevant even in the context of the development of Internet technologies. This model still remains dominant for DBMS. Its wide application and long “life” period indicate that we are dealing with a quite mature technology, which in itself is a significant advantage.
Another advantage of this model is that almost all relational database management systems support transactions.. They operate on an all-or-nothing basis.
3 Popular Relational Databases for Web Development
MySQL
The American corporation Oracle acquired this open database management system together with Sun Microsystems. A survey conducted by the StackOverflow.com portal two years ago, in which 65,000 users took part, showed that about 55.6% of developers work with MySQL.
Such popularity is due to the high speed of data management and the possibility of free use. Subsequently, when developers appreciated its speed and free of charge, this DBMS conquered the world Internet. So far, MySQL remains the most convenient data management system for working with both web applications and pages.
At the same time, this DBMS receives serious support from developers of programming languages. Today, almost all popular languages have an interface for working with MySQL.
SQLite
Its main advantage is considered to be its embeddability, which is due to the fact that SQlight, unlike other DBMS, is not an application like “client-server”, but a pluggable library.
PostgreSQL
It is the most advanced relational database management system. PostgreSQL is a free object-relational DBMS.
The uniqueness of this DBMS is that in addition to the standard data types supported by other relational systems, it can work with financial information, network addresses, JSON, XML and geometric data. Moreover, PostgreSQL can create its own data types.
Prospects for Relational Databases
Existing types of relational databases have been developing for a long time in terms of increasing productivity, security and reliability. They have become more convenient to maintain, but at the same time their structure has become much more complicated. Autonomous DBs have all the advantages of relational systems, support the same functions, but in addition to this, they are able to use machine learning and artificial intelligence tools to control and increase the speed of response to requests and management efficiency.
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MySQL Database: Reasons for Its Popularity
For example, to make queries run faster, self-managing databases perform forecasting and check indexes. The improved results are then put to practical use. Remarkably, all these processes occur without administrator intervention. In other words, autonomous databases can continuously improve their performance without human intervention.
