SQL Server DAX Terminology
By: Siddharth Mehta
It is important to understand basic terms used while working with SSAS and DAX before we start diving into the details of DAX. A tabular model is typically composed of tables, relationships, measures and hierarchies. In this chapter we will cover the basic meanings of these terms, as we will be working with these in the context of DAX in the upcoming chapters.
Table - A table is a set of columns that can be imported from a data source or can be added manually as calculated columns.
Table metadata - All the database objects like relationships, measures, perspectives, etc. are all metadata objects within the context of a table.
Data - In a tabular model, data is populated either by importing data or by creating data manually in calculated fields called calculated columns.
Relationships - In a tabular model, a relationship is a connection between two tables which correlates data between two tables.
Calculations - In a tabular model, DAX formulas include functions, operators, and other constructs to create advance calculations.
Measures - In a tabular model, a measure is a calculation created using a DAX formula.
Hierarchies - In a tabular model, hiearchies define relationships between two or more columns in a table. Each level in a hierarchy is a representation of a column in a table.
Calculated columns - A calculated column is a column that is added to an existing table using a DAX formula for the values stored in that column.
Measures - A measure is a dynamic DAX formula which is calculated based on context of the query.
Row Filters - In a tabular model, a row filter defines the scope of data visible to any role.
- Consider reading this article to gain some more understanding about the difference between multidimensional and tabular models.