$structVariantType = Variant<a: Int32, b: String>;

$data = [
    <|variantValue: Variant(1,       "a", $structVariantType)|>,
    <|variantValue: Variant("world", "b", $structVariantType)|>,
];

SELECT variantValue, variantValue.a AS aAlternative, variantValue.b AS bAlternative FROM as_table($data);