这是Oracle sql的一个局限性：您不能从子查询中引用超过1级的父查询元素。
CREATE OR REPLACE FUNCTION get_title(p_position_id NUMBER) RETURN VARCHAR2 IS
l_result LONG;
l_position_num NUMBER := 0;
BEGIN
FOR cc IN (SELECT position_title
FROM position_table
WHERE position_table.position_id = p_position_id
AND rownum <= 3) LOOP
l_result := cc.position_title || ',';
l_position_num := l_position_num + 1;
END LOOP;
RETURN l_result || rpad(',', 3 - l_position_num, ',');
END;
您的查询将如下所示：
select
name,
phone,
address,
get_title(p.position_id) title
from person_view p
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