The primary purpose of SQL is to retrieve and manipulate data stored in relational databases. It allows users to define the structure of databases, create tables to store data, insert new records, update existing records, and retrieve information through queries. SQL is a declarative language, meaning you describe what you want to achieve, and the database management system (DBMS) takes care of executing the necessary operations.
SQL operates on relational databases, which consist of one or more tables that are related to each other based on common data elements. These tables store data in rows and columns, similar to a spreadsheet. SQL provides a rich set of commands, commonly referred to as SQL statements, to interact with these tables and perform various operations.
Some of the fundamental SQL statements include:
- SELECT: Used to retrieve data from one or more tables based on specified conditions.
- INSERT: Used to add new records into a table.
- UPDATE: Used to modify existing records in a table.
- DELETE: Used to remove records from a table.
- CREATE: Used to create new tables, views, indexes, or other database objects.
- ALTER: Used to modify the structure of an existing database object.
- DROP: Used to delete tables, views, indexes, or other database objects.
SQL also provides capabilities for sorting and grouping data, filtering results based on specific criteria, joining multiple tables together, and performing calculations and aggregations on the data.
To work with SQL, you typically use a DBMS such as MySQL, Oracle, SQL Server, PostgreSQL, or SQLite. These database systems provide the necessary software to create, manage, and interact with databases using SQL commands.
Overall, SQL is a powerful and widely adopted language for managing and manipulating relational databases, making it a crucial skill for developers, data analysts, and anyone involved in working with data.
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