我正在尝试在PostgreSQL上创建一个函数,并且在使用局部变量时遇到一些问题。这是我的代码:
DECLARE query RECORD;
DECLARE schema_name TEXT;
BEGIN
FOR query IN SELECT * FROM context WHERE created_at + make_interval(days => duration) <= CURRENT_TIMESTAMP LOOP
SELECT lower(quote_ident(query.title)) INTO schema_name;
DROP SCHEMA schema_name CASCADE;
DELETE FROM context WHERE id = query.id;
END LOOP;
RETURN 1;
END;
$$ LANGUAGE plpgsql;
select和delete查询工作正常,我进行了一个测试,返回了schema_name变量的值,没关系。
我的问题是这条线:
DROP SCHEMA schema_name CASCADE;
我收到错误消息,因为“模式'schema_name'不存在”。我非常感谢有关如何使用此变量进行放置查询的任何想法。
您需要为此使用动态SQL:
DECLARE
query RECORD;
BEGIN
FOR query IN SELECT id, lower(title) as title
FROM context
WHERE created_at + make_interval(days => duration) <= CURRENT_TIMESTAMP
LOOP
execute format('DROP SCHEMA %I CASCADE', query.title);
DELETE FROM context WHERE id = query.id;
END LOOP;
RETURN 1;
END;
$$ LANGUAGE plpgsql;