SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 2) ExpressionList (children 1) Function in (children 1) ExpressionList (children 2) Identifier c2 Literal Tuple_(\'abc\', NULL) TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 1) TableIdentifier nullt