ReadonlyAliasThe alias; null when none is written.
ReadonlyAliasHow the alias is written: expr AS a, expr a, a = expr or expr 'a'.
ReadonlyExpressionThe expression, without the alias. For a star item it covers the star.
ReadonlyIsWhether the item is * or qualifier.*.
ReadonlyKindReadonlySpanReadonlyStarThe qualifier of qualifier.*; null for * and for other items.
One select-list item.