Tables¶

Introduction¶

The foundation of relational databases is the relational theory, and at its base is the Entity-Relationship Model (E-R). Simply put, it consists in representing a fragment of reality by means of entity relationships, i.e. a structure for storing data. In the case of relational databases, it will always be a set of tables into which information is aggregated. In addition, the tables will have specific links with each other:

ENTRY CLASS, RELATION (ER Model) <=> TABLE (RDBMS) <=> CLASS (object-oriented languages)

Table¶

According to relational database theory, tables are where data is stored. In addition, the relationship itself is also a table. This structure consists of lines and columns. Each line describes one record (single information / data set). The column is responsible for describing the properties / structure of a given record.

The above table is responsible for storing personal data. This table consists of three columns:

• first name
• name
• birth date

Three records representing three independent pieces of information are entered in the table.