Question

我正在尝试通过2列查询压缩订单，按1列查询订单和细分列。如果这有一个正确的名称，我将非常感谢它知道它是什么！

示例：

ocean
name     | type    | colour
fishy    | salmon  | red
splishy  | salmon  | red
splashy  | salmon  | pink
sploshy  | salmon  | pink
floaty   | whale   | blue
humprhey | whale   | grey
wilson   | whale   | grey

寻找（我不确定这是做什么的）：

type  | count | colour breakdown
salmon| 4     | 2 red, 2 pink
whale | 3     | 1 blue, 2 grey

优先使用最少的字符串函数。

不确定如何继续：

（按一栏排序）

SELECT o.type, count(*)
FROM ocean o
GROUP BY `type`

type  | count
salmon| 4
whale | 3

（按两栏排序）

SELECT o.type, o.colour, count(*)
FROM ocean o
GROUP BY `type`, `colour`

type  | colour     | count
salmon| red        | 2
salmon| pink       | 2
whale | blue       | 1
whale | grey       | 2

Answer 1

丑陋，未经测试，但可能只是做你想要的：

SELECT type, SUM(color_count),
   GROUP_CONCAT(CONCAT(color_count, ' ', colour) SEPARATOR ', ') AS colour_breakdown
FROM (
    SELECT type, colour, COUNT(colour) AS colour_count
    FROM ocean
    GROUP BY type, colour
) AS subt
GROUP BY type

Answer 2

使用第二个查询作为数据源，您可以使用group_concat()获取所需的输出：

select type, sum(`count`), group_concat(colBreak separator ',') as color_breakdown
from
    (
        SELECT 
            o.type, 
            o.colour, 
            count(o.type) as `count`, 
            concat(o.colour, ' ', count(o.type)) as colBreak
        FROM ocean o 
        GROUP BY `type`, `colour`
    ) as a
group by type;

MYSQL按两列分组压缩成一列一列

2 个答案: