What is a relational database?

The so-called relational database refers to a database that uses relational models to organize data. The relational model was first proposed in 1970 by Dr. E.F.Codd, a researcher at IBM. In the following decades, the concept of relational model has been fully developed and gradually became the mainstream model of database architecture. Simply put, a relational model refers to a two-dimensional table model, and a relational database is a data organization composed of two-dimensional tables and their relationships. The following is a list of commonly used concepts in relational models. Relationships: It can be understood as a two-dimensional table, and each relationship has a relationship name, which is usually called the table name. Tuple: it can be understood as a row in a two-dimensional table, which is usually called a record in a database. Attribute: It can be understood as a column in a two-dimensional table and is often called a field in a database. Domain: the value range of the attribute, that is, the value limit of a column in the database. Keywords: A set of attributes that can uniquely identify tuples. A database is usually called a primary key and consists of one or more columns. Relationship pattern: it refers to the description of the relationship, and its format is: relationship name (attribute 1, attribute 2, …, attribute n). It is usually called table structure in database.