SQL (Structured Query Language) is a programming language used for managing and manipulating relational databases. It is used to insert, update, and query data stored in tables, as well as create and modify the structure of the database itself. Common SQL commands include SELECT, INSERT, UPDATE, and DELETE. It has grown to be the "standard" way of accessing databases such as MySQL, MariaDB, PostgreSQL, Microsoft SQL, Oracle, etc.
The data is most commonly stored in persistent storage, allowing for the databases to be ACID compliant.
SQL is widely used in various industries for data management, reporting, and data analytics. SQL can also be used in conjunction with other programming languages such as Python, PHP, and Java to create web applications and data-driven systems.
What is SQL used for?
This language is used to interact with the database in order to create, read, update or delete records across one or multiple tables. Since the language has become a pillar of many applications, it is considered a standard and drivers to access SQL Databases are available across multiple platforms and programming languages such as PHP, Node.js, Python, .NET, Java, Go, Ruby, etc.
Use cases for SQL
SQL can be used to perform a variety of tasks, including:
Retrieving data from a database: SQL's
SELECTstatement is used to retrieve data from one or more tables in a database. The statement can be used to select specific columns, filter rows based on certain conditions, and sort the results.
Inserting data into a database: SQL's
INSERTstatement is used to add new rows of data to a table in a database.
Updating data in a database: SQL's
UPDATEstatement is used to modify existing data in a table.
Deleting data from a database: SQL's
DELETEstatement is used to remove rows of data from a table.
Creating and modifying database structures: SQL can be used to create new tables, alter the structure of existing tables, and create and manage indexes.
In addition to the basic SQL commands, there are also several advanced features of SQL that can be used to perform more complex tasks such as:
Joins: SQL's join operators (e.g.,
OUTER JOIN) are used to combine data from multiple tables based on a common column.
Subqueries: SQL subqueries are used to nest one
SELECTstatement within another. This can be used to retrieve data from multiple tables based on the results of a previous query.
Stored Procedures: SQL stored procedures are pre-compiled SQL statements that can be reused multiple times. Stored procedures can be used to encapsulate complex logic, security, and validation.
Transactions: SQL transactions allow you to group multiple SQL statements together into a single unit of work. This allows you to ensure that either all of the statements are executed, or none of them are.
Views: A SQL view is a virtual table based on the result-set of an SQL statement. It does not store data itself, but it provides a way to access data from one or more tables as if it were a single table.
Overall, SQL is a very powerful and versatile language that can be used to manage and manipulate data in relational databases. With its wide range of features, it can be used to perform a wide variety of tasks, from simple data retrieval to complex data analytics.