使用GROUP BY ROLLUP可实现分层统计,生成逐级汇总结果,结合GROUPING函数区分汇总行;CUBE用于多维交叉汇总;窗口函数可在保留明细的同时计算层级聚合;UNION方法灵活拼接各层数据,适用于复杂定制场景。

在 SQL 中实现分层统计,通常是指对数据按多个维度逐级汇总,比如先按大类分组,再在大类下按小类细分,并同时展示各级别的聚合结果。可以通过 GROUP BY 配合 ROLLUP、CUBE 或使用 窗口函数 来实现。
示例:假设有销售表 sales(region, department, amount),想按 region → department 分层统计总金额。
SELECT
region,
department,
SUM(amount) AS total_amount
FROM sales
GROUP BY ROLLUP (region, department);
结果会包含:
可通过 GROUPING() 函数区分 NULL 是数据还是汇总行:
SELECT
region,
department,
SUM(amount) AS total_amount,
GROUPING(region) AS is_region_total,
GROUPING(department) AS is_dept_total
FROM sales
GROUP BY ROLLUP (region, department);
GROUP BY CUBE (region, department)
会输出 region、department、组合、以及总计四种级别的汇总。
示例:在每条记录中显示部门金额及其所在区域的总金额。
SELECT
region,
department,
amount,
SUM(amount) OVER (PARTITION BY region) AS region_total,
SUM(amount) OVER (PARTITION BY region, department) AS dept_total
FROM sales;
这样可以在不减少行数的前提下,附加各层级的聚合信息。
-- 明细层 SELECT 'detail' AS level, region, department, SUM(amount) AS total FROM sales GROUP BY region, department UNION ALL -- 区域层 SELECT 'region' AS level, region, NULL, SUM(amount) FROM sales GROUP BY region UNION ALL -- 总计 SELECT 'total', NULL, NULL, SUM(amount) FROM sales ORDER BY region, department;
这种方式便于添加自定义标签和排序。
基本上就这些方法,根据实际需求选择:ROLLUP 最简洁,窗口函数适合增强明细,UNION 最灵活。
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