The full form of DAX is Data Analysis Expression. A DAX function is a predefined formula which performs calculations on values provided to it in arguments. The arguments in a function need to be in a particular order and can be a column reference, numbers, text, constants, another formula or function, or a logical value such as TRUE or FALSE. Every function performs a particular operation on the values enclosed in an argument. You can use more than one argument in a DAX formula.

Key Points about DAX Functions

Here are some unique facts about DAX functions that you must know in order to understand them better:

• • Any DAX function always refers to a complete column/field or a table. It will never refer to individual values. If you want to use the functions on separate values within a column, you need to apply filters in a DAX formula.
• • DAX functions provide the flexibility to create a formula that is applied on a row-by-row basis. The calculations or formulas get applied as per the context of the values in each row.
• • In some cases, DAX functions return a full table which can be used in other DAX formulas that need a complete set of values. However, you cannot display this table’s contents.
• • DAX functions have a category known as time intelligence functions. Such functions are used to calculate time/date ranges and periods.

DAX Function Types

• • Date & Time Functions
• • Time Intelligence Functions
• • Logical Functions