From the course: Excel Business Intelligence: Data Modeling 101

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Relationship cardinality

Relationship cardinality - Microsoft Excel Tutorial

From the course: Excel Business Intelligence: Data Modeling 101

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Relationship cardinality

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- [Instructor] All right, time to talk about cardinality and specifically table relationship cardinality. So by definition, cardinality refers to the uniqueness of values in a column. So if you hear people talk about a one-to-one relationship or a one-to-many or many-to-many, those are examples of relationship cardinalities. Now in Power Pivot, at least in the current version, all relationships in a data model really should follow a one-to-many cardinality. And you already know what this means. It just means that each column or key that we're using to join tables can only have one instance of each unique value in the lookup table, which is exactly what makes those primary keys. But they may have many instances of each unique value in the data tables. That's why we call them foreign keys. So none of this really new. It's just kind of putting the academic definition around it. So in this case that we're looking at here, now we're joining calendar to the Food Mart transactions data…

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