Overview about database structure

Tables, Rows, and Columns

A relational database organizes data into tables, where each row (record) represents one entity and each column (field) represents an attribute of that entity.

Keys

• Primary Key: uniquely identifies each row in a table.
• Foreign Key: a column that references the primary key of another table, creating relationships between tables.

Schemas and Constraints

A schema defines the structure of the database—tables, columns, data types, and relationships—while constraints (like NOT NULL, UNIQUE, or CHECK) enforce data integrity rules.

Indexes

Indexes are special structures that speed up data retrieval, at the cost of some extra storage and slightly slower writes.