如何获得每列的总和？

Question

创建临时表

CREATE TEMP TABLE total(
gid SERIAL,
zoom smallint NOT NULL,
point integer NOT NULL,
size integer NOT NULL
);

插入数据

INSERT INTO total(zoom, point, size) VALUES(9,51,21);
INSERT INTO total(zoom, point, size) VALUES(9,75,45);
INSERT INTO total(zoom, point, size) VALUES(9,74,34);
INSERT INTO total(zoom, point, size) VALUES(10,75,4);
INSERT INTO total(zoom, point, size) VALUES(10,72,63);
INSERT INTO total(zoom, point, size) VALUES(10,85,22);

计数点，根据缩放增加尺寸

SELECT zoom,
       count(*) AS point,
       SUM(size) AS size
FROM total
GROUP BY zoom
ORDER BY zoom;

结果：

 zoom | point | size 
------+-------+------
    9 |     3 |  100
   10 |     3 |   89
(2 rows)

题

如何返回每列的总数？

想要的结果：

 zoom | point | size 
------+-------+------
    9 |     3 |  100
   10 |     3 |   89
------+-------+------        
Total |     6 |  189

Answer 1

模拟汇总的方法是简单地运行执行汇总的第二个查询。但是，列中的所有值必须具有相同的数据类型。当您想显示标签时，'Total'您还需要将zoom基本查询中的数字转换为文本：

但由于您想按实际缩放值排序，您还需要在结果中保留整数值。

在sort_order确保必要从工会的第一部分实际上行留“顶部”

select zoom, point, size
FROM (
  SELECT zoom::text as zoom,
         zoom as zoom_value,
         count(*) AS point,
         SUM(size) AS size, 
         1 as sort_order
  FROM total
  GROUP BY zoom
  UNION ALL
  SELECT 'Total', 
         null,
         count(*) AS point,
         SUM(size) AS size, 
         2 as sort_order
  FROM total
) t
order by sort_order, zoom_value;

这将返回：

select zoom, point, size
FROM (
  SELECT zoom::text as zoom,
         zoom as zoom_value,
         count(*) AS point,
         SUM(size) AS size, 
         1 as sort_order
  FROM total
  GROUP BY zoom
  UNION ALL
  SELECT 'Total', 
         null,
         count(*) AS point,
         SUM(size) AS size, 
         2 as sort_order
  FROM total
) t
order by sort_order, zoom_value;

使用最新的 Postgres 版本，您可以执行以下操作：

SELECT case when grouping(zoom) = 1 then 'Total' else zoom::text end,
       count(*) AS point,
       SUM(size) AS size
FROM total
GROUP BY rollup (zoom)
order by zoom;