Oracle 4种等价SQL

最新推荐文章于 2022-02-16 17:30:22 发布

iteye_20812

最新推荐文章于 2022-02-16 17:30:22 发布

阅读量273

点赞数

CC 4.0 BY-SA版权

分类专栏： Oracle 文章标签： Oracle

本文链接：https://blog.youkuaiyun.com/iteye_20812/article/details/82445621

Oracle 专栏收录该内容

84 篇文章

订阅专栏

本文深入探讨了SQL查询中如何通过多级筛选与数据匹配，实现复杂数据集的有效过滤与精确检索。从基本的COUNT(1)查询出发，逐步引入GROUP BY、JOIN、DISTINCT等关键操作，展示如何高效地处理并分析大型数据库中的信息。重点涵盖了通过子查询、NOT EXISTS等逻辑条件构建高级查询策略，确保数据准确性和效率。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >


SELECT COUNT (1) FROM (SELECT k001 FROM ( SELECT k001 FROM kbib GROUP BY k001) k
WHERE NOT EXISTS ( SELECT 1 FROM ( SELECT k003 FROM calb GROUP BY k003) c WHERE k.k001 = c.k003))

SELECT COUNT (1) FROM (SELECT k001 FROM ( SELECT k001 FROM kbib GROUP BY k001) k
WHERE NOT EXISTS ( SELECT k003 FROM calb WHERE k.k001 = k003 GROUP BY k003))

SELECT count (1) FROM (SELECT * FROM ( SELECT k001 FROM kbib GROUP BY k001) k
WHERE k.k001 NOT IN ( SELECT k003 FROM calb c WHERE k.k001 = c.k003 GROUP BY k003))


SELECT count (1) FROM (SELECT * FROM ( SELECT DISTINCT k001 FROM kbib) k
WHERE k.k001 NOT IN ( SELECT DISTINCT k003 FROM calb c WHERE k.k001 = k003))