SQL is a language for managing relational databases from "summary" of SQL and Relational Theory by C. Date
SQL is indeed a language, but it's not a general-purpose language like C++ or Java. Rather, it's a special-purpose language, specifically designed for managing relational databases. In practice, what that means is that SQL is used to define and manipulate tables in those databases, and also to access the data stored in those tables. The term relational database refers to a collection of tables, where each table is a two-dimensional structure, somewhat like a spreadsheet. Each table consists of rows and columns, with each row representing a single entity of interest (such as an employee or a product), and each column representing an attribute of that entity (such as the employee's name or the product's price). But what exactly does it mean to manage a relational database? Well, that's a rather broad and somewhat vague concept. At a high level, it includes such tasks as creating and maintaining tables, inserting new data into those tables, updating existing data, and deleting unwanted data. It also includes queries, which essentially means extracting specific subsets of the data stored in the tables. The language SQL provides a set of commands for carrying out all these tasks and more. For example, there are commands for creating tables, altering tables, deleting tables, inserting rows, updating rows, deleting rows, and selecting rows. There are also commands for defining constraints on tables, such as primary key constraints, foreign key constraints, and check constraints. Moreover, SQL is a declarative language, meaning that you specify what you want to achieve rather than how to achieve it. In other words, when you write an SQL query, you're telling the database system what data you want to retrieve, but you're not telling it how to retrieve that data. In summary, SQL is a language specifically designed for managing relational databases. It provides a set of commands for defining and manipulating tables, as well as for accessing the data stored in those tables. It is a declarative language, allowing users to specify what they want to achieve without having to worry about the details of how to achieve it.
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