union.tag

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

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 (of type 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' |