Contents
- What is SQL
- Why SQL is Needed
- Subtypes of SQL
- Alternatives to SQL
- Advantages and Disadvantages of SQL for Business
What is SQL
SQL, or Structured Query Language, is a language used to write queries to databases. With such queries, websites and applications can retrieve information from databases, including user or product data found in catalogs. SQL is necessary for interacting with database management systems (DBMS), as the databases themselves cannot interpret queries and provide answers. They are simply a set of tables with data, and specialized systems managed using SQL are required to process them.
Database management systems allow for the creation, population, and modification of databases, as well as retrieving or recording information. SQL allows commands to be sent to these systems to perform various actions. Users or programs formulate SQL queries, and in response, the DBMS retrieves the necessary data from the database and sends it back.
Why SQL is Needed
The main purpose of using SQL is to retrieve, modify, and manage data in the database. Here are some key functions performed by SQL:
Retrieving Information
Every time a website or program needs data from the database, it uses an SQL query. For example, if a user selects filters to display products at a certain price, the server creates a query to the database with these conditions.
Modifying Data in the Database
Often, it is necessary to update information, such as product prices or user contact details. SQL queries allow for data to be overwritten to keep it current. For instance, prices for thousands of products that meet specified criteria can be changed simultaneously.
Managing Data Structures
SQL also provides the ability to create and modify tables. This allows for the addition of new fields, removal of outdated tables, and management of the database structure. When a new user registers, records with a username and password are created.
Access Management
SQL allows for setting access rights for users, which includes managing the ability to read, write, and modify data. This can apply to both individuals and automated services.
Transactions
SQL allows for creating transactions, which are groups of commands executed sequentially. If any command fails, all other commands are also rolled back, which is especially important for maintaining data integrity, as in the case of online money transfers.
Subtypes of SQL
There are several dialects of SQL, each designed to work with specific database management systems. The main ones include:
- T-SQL — for Microsoft SQL Server
- PL/SQL — for Oracle
- MySQL — for the eponymous system
- PL/pgSQL — for PostgreSQL
While the basic syntax of these dialects is similar, they differ in extensions and query writing features, making them incompatible with one another. When creating a website, developers choose a DBMS, which in turn determines the SQL dialect used.
Alternatives to SQL
SQL is the standard tool for working with relational databases; however, there are also non-relational databases that use alternative query languages. For such databases, programming languages or specialized query languages are typically used.
Relational Databases
Relational databases represent information in the form of related tables with a rigid structure, making SQL necessary for their management.
Non-relational Databases
Non-relational databases use more flexible data formats, such as JSON documents or key-value pairs, and can function without SQL. They are often used in projects where speed is more important than data structure.
Advantages and Disadvantages of SQL for Business
SQL is the foundation of most websites and applications, and its popularity can be attributed to several advantages:
- Versatility: The fundamentals of SQL are the same for all dialects, making migration between systems easier.
- Consistency: SQL operates on strict principles, reducing the risk of data loss.
- Flexibility in Querying: The ability to create complex queries to extract data under multiple conditions.
- Stability: SQL has been around for a long time, and specialists who know it can be easily found.
However, SQL also has disadvantages. It is limited to relational databases, which may be less effective for projects with high data processing speed and complex architectures, making them less suitable for distributed systems compared to NoSQL solutions.