Identify dimension table relationships

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Table relationships are important in relational databases to enforce data integrity. A relationship exists between two tables when one or more columns from one table match one or more columns on another table, or in some cases within the same table. 

In SQL Server, table relationships are defined using foreign key constraints. A foreign key constraint is typically defined between a column in a table to a primary key column in another table.

Relationships can be considered zero-to-many (0:M), one-to-one (1:1) or one-to-many (1:M) relationships depending on their cardinality.

Many-to-many relationships often involve a third intermediate table that relate to the other two tables. These intermediate tables are often fact tables or relationship tables often referred to as fact-less fact tables.

During a data warehouse modeling exercise, it is important to identify how dimension tables relate to each other. To effectively identify these relationships, during the modeling exercise the business processes need to be identified and modeled along with the dimensions that directly relate to them. An Enterprise Business Matrix (EBM), is valuable tool that can be used to identify and document how dimension tables and business processes relate to each other.











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