SQL
Union Functions
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| Name | Description |
|:--|:-------|
| [`union.tag`](#::uniontag) | Dot notation serves as an alias for `union_extract`. |
| [`union_extract(union, 'tag')`](#::union_extractunion-tag) | Extract the value with the named tags from the union. `NULL` if the tag is not currently selected. |
| [`union_value(tag := any)`](#::union_valuetag--any) | Create a single member `UNION` containing the argument value. The tag of the value will be the bound variable name. |
| [`union_tag(union)`](#::union_tagunion) | Retrieve the currently selected tag of the union as an [Enum](#docs:sql:data_types:enum). |