Database Systems with SQL - Full Course - Database Systems - Cardinality

Cardinality is the number of associations between entities, or the numeric relationship between rows of one table to rows of another table. Relationship maximum is the biggest number of instances of one entity that can relate to a row of another entity. Each of the related entities has a relationship maxima, were the number 1 means one, and M means many. Relationship minimum is the smallest number of instances that an entity can relate to a single row of another entity. Each of the related entities has a relationship minima, which are denoted as either (1) or (0) in parenthesis. There are times when the minimum can be bigger than 1, such as (2) when there are two required ways to authenticate when signing into your bank account online. In the example, every song belongs to an Artist, but not all Artist’s have a song. Attribute maximum means that entities have an Entity-Has-Attribute relationship with their attributes. That means that each attribute should be singular, plural, and unique. Compared to attribute minimum, which means that each attribute instance can either have no attributes or a required attribute defined. Subscribe to Appficial for more programming videos coming soon. Also, don't forget to click LIKE and comment on the video if it helped you out!