Open map List

Relation

Introduction

In relational data models, a database is viewed as a collection of relations, also commonly referred to as tables. A table or relation is itself a collection of tuples (or records). In fact, each table is a collection of tuples that are similarly shaped. By this, we mean that a tuple has a fixed number of named fields (also known as attributes).

Examples

Figure: An example of a small database consisting of three relations (tables), all with three attributes, and three, four and four tuples, respectively. PrivatePerson / Parcel / TitleDeed are the names of the three tables. Surname is an attribute of the PrivatePerson table; the Surname attribute value for person with TaxId ‘101-367’ is ‘Garcia’.

Learning outcomes

  • 5 - Data management: relational database and DBMS

    Describe and explain the structure and components of a relational data model and a relational database (level 1 and 2). Describe and explain what a Database Management System (DBMS) is and how it links to a GIS.

  • 6 - Data retrieval and queries

    Explain the basic concepts of data retrieval (attribute and spatial queries) and formulate queries to make a selection on attributes and geospatial data from a spatial database.

Outgoing relations

Incoming relations

Learning paths