Oracle判断查询结果是否为空的方法主要有以下几种：
SELECT COUNT(*) FROM table_name WHERE condition;
SELECT column_name FROM table_name WHERE EXISTS (SELECT * FROM table_name WHERE condition);
SELECT column_name FROM table_name WHERE column_name IS NULL;
SELECT column_name FROM table_name WHERE condition AND ROWNUM = 1;
以上是Oracle中判断查询结果是否为空的几种常用方法，根据具体的需求可以选择合适的方法使用。
