UNION - Daxplained

UNION is a DAX function that returns the union of two or more tables with matching columns.

Syntax

UNION( [ Table, ... ] )

Argument	Properties	Description
Table	Repeatable	A table that will participate in the union.

A table that contains all the rows from each of the two table expressions.

The two tables must have the same number of columns.
Columns are combined by position in their respective tables.
The column names in the return table will match the column names in table_expression1.
Duplicate rows are retained.
The returned table has lineage where possible. For example, if the first column of each table_expression has lineage to the same base column C1 in the model, the first column in the UNION result will have lineage to C1. However, if combined columns have lineage to different base columns, or if there is an extension column, the resulting column in UNION will have no lineage.
When data types differ, the resulting data type is determined based on the rules for data type coercion.
The returned table will not contain columns from related tables.
This function is not supported for use in DirectQuery mode when used in calculated columns or row-level security (RLS) rules.

The following expression creates a union by combining the USAInventory table and the INDInventory table into a single table:

UNION(UsaInventory, IndInventory)

USAInventory

Country/Region	State	Count	Total
USA	CA	5	500
USA	WA	10	900

INDInventory

Country/Region	State	Count	Total
IND	JK	20	800
IND	MH	25	1000
IND	WB	10	900

Return table,

Country/Region	State	Count	Total
USA	CA	5	500
USA	WA	10	900
IND	JK	20	800
IND	MH	25	1000
IND	WB	10	900

Other functions related to UNION are:

Contribute » | Contributors: Rick de Groot
Microsoft documentation: https://learn.microsoft.com/en-us/dax/union-function-dax