How does the UNION function (DAX) work?
UNION function (DAX) is where a union (join) table is formed from a pair of tables.
UNION Formula Syntax
UNION(<table_expression1>, <table_expression2>, [, <table_expression>]
How do you use the UNION function?
The two tables must have the same number of columns.
Columns are combined by position in their respective tables.
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Considerations when using the UNION function
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.
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Formula examples using the UNION function