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Union Functions

Name	Description
`union.tag`	Dot notation serves as an alias for `union_extract`.
`union_extract(union, 'tag')`	Extract the value with the named tags from the union. `NULL` if the tag is not currently selected.
`union_value(tag := any)`	Create a single member `UNION` containing the argument value. The tag of the value will be the bound variable name.
`union_tag(union)`	Retrieve the currently selected tag of the union as an Enum.

Dot notation serves as an alias for union_extract.

Query

SELECT (union_value(k := 'hello')).k AS k;

Result

 k------- hello

Extract the value with the named tags from the union. NULL if the tag is not currently selected.

Query

SELECT union_extract(union_value(k := 'hello'), 'k') AS k;

Result

 k------- hello

Description	Create a single member `UNION` containing the argument value. The tag of the value will be the bound variable name.
Example	`union_value(k := 'hello')`
Result	`'hello'::UNION(k VARCHAR)`

Retrieve the currently selected tag of the union as an Enum.

Query

SELECT union_tag(union_value(k := 'foo')) AS union_tag;

Result

 union_tag----------- k