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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.

`union.tag`

| Description | Dot notation serves as an alias for union_extract. | | Example | (union_value(k := 'hello')).k | | Result | string |

`union_extract(union, 'tag')`

| Description | Extract the value with the named tags from the union. NULL if the tag is not currently selected. | | Example | union_extract(s, 'k') | | Result | hello |

`union_value(tag := any)`

| 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) |

`union_tag(union)`

| Description | Retrieve the currently selected tag of the union as an Enum. | | Example | union_tag(union_value(k := 'foo')) | | Result | 'k' |