MySQL在1个表中选择不同的记录并根据另一个表中的值计算每个组

Question

表 1：

| user           | bid |
---------------------------
|    may    |      0.06      |
|    dee    |      0.05      |
|    jay    |      0.04      |
|    mac    |      0.03      |
|    dee    |      0.02      |
|    mac    |      0.01      |

表 2：

| user          | ratio|
---------------------------
|    dee    |      .25      |
|    jay    |      .45      |
|    mac    |      .85      |
|    fil    |      .75      |
|    may    |      .95      |

我想根据表 2 中的配给计算表 1 中有多少不同的用户落在特定范围 (0-.99) 内。

输出：

| Ratio_Group     | Count|
---------------------------
|    0.00-0.25 |      1     |
|    0.25-0.50 |      1     |
|    0.50-0.75 |      0     |
|    0.75-0.99 |      2     |

每个比率分组是否有 1 个查询，我可以根据他们在表 2 中的分组来计算表 1 中的不同用户？我使用了 IF 和 COUNT 语句的组合，但表 1 中的每一行都被评估和计数，而不仅仅是 DISTINCT 用户，因此我得到了一个夸大的结果。

例如：

 COUNT((IF table1.user <0.25,1,0))
 COUNT((IF table1.user BETWEEN 0.25 AND 0.50,1,0))
 etc...

4 个查询中的每一个都将在存储过程中使用，因此每个比率分组需要 1 个查询，因此我可以将每个组的结果分配给存储过程中的变量。

Answer 1

您可以将SUM 与BETWEEN 和DISTINCT 组合使用

SELECT
SUM(DISTINCT `table2`.`ratio` BETWEEN 0.00 AND 0.25) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) GROUP BY table1.user

SELECT
SUM(DISTINCT `table2`.`ratio` BETWEEN 0.25 AND 0.50) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) GROUP BY table1.user

SELECT
SUM(DISTINCT `table2`.`ratio` BETWEEN 0.50 AND 0.75 ) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) GROUP BY table1.user

SELECT
SUM(DISTINCT `table2`.`ratio` BETWEEN 0.75 AND 0.99) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) GROUP BY table1.user

或者你可以把它们组合成一个

SELECT  '0.00 - 0.25' Ratio_Group ,
SUM(DISTINCT `table2`.`ratio` BETWEEN 0.00 AND 0.25) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) GROUP BY table1.user
UNION ALL
SELECT '0.25 - 0.50' Ratio_Group ,
SUM(DISTINCT `table2`.`ratio` BETWEEN 0.25 AND 0.50) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) GROUP BY table1.user
UNION ALL
SELECT '0.50 - 0.75' Ratio_Group ,
SUM(DISTINCT `table2`.`ratio` BETWEEN 0.50 AND 0.75 ) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) GROUP BY table1.user
UNION ALL
SELECT '0.75 - 0.99' Ratio_Group ,
SUM(DISTINCT `table2`.`ratio` BETWEEN 0.75 AND 0.99) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) GROUP BY table1.user

编辑下面的查询将统计每个比率组的不同用户

SELECT  '0.00 - 0.25' Ratio_Group ,
COUNT(DISTINCT `table2`.`user` ) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) 
WHERE `table2`.`ratio` BETWEEN 0.00 AND 0.25

UNION ALL

SELECT '0.25 - 0.50' Ratio_Group ,
COUNT(DISTINCT `table2`.`user`) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) 
WHERE  `table2`.`ratio` BETWEEN 0.25 AND 0.50

UNION ALL

SELECT '0.50 - 0.75' Ratio_Group ,
COUNT(DISTINCT `table2`.`user` ) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) 
WHERE `table2`.`ratio` BETWEEN 0.50 AND 0.75
UNION ALL

SELECT '0.75 - 0.99' Ratio_Group ,
COUNT(DISTINCT `table2`.`user`) `count`
FROM table1 JOIN table2 ON (table1.user =table2.user) 
WHERE `table2`.`ratio` BETWEEN 0.75 AND 0.99

See Fiddle Demo

Answer 2

如果您不介意只抓取有成员的群组，您可以执行以下操作。它使用内部查询来获取唯一成员及其相应的比率，然后使用包含表按这些比率将它们分组到比率组中。好消息是你没有硬编码行组，这不是很像 SQL；缺点是您看不到计数为 0 的行“成员”。

SELECT
    CONCAT(
        ((CEIL(ratio * 4) * 0.25 ) - 0.25),
        " - ",
        (CEIL( ratio *4 ) * 0.25)
    ) AS ratio_group,
    COUNT(user) AS user_count
FROM (
    SELECT
        t1.user,
        t2.ratio
    FROM
        `table1` t1
    INNER JOIN
        `table2` t2 ON t2.user = t1.user
    GROUP BY
        t1.user
) virtual_table
GROUP BY
    CEIL(ratio * 4)

根据您的附加 cmets，您可以将所有数据组合成一个字符串，然后像这样分配给一个变量。这是一个混蛋的地狱。你如何处理这些数据（此时它本质上是一个 CSV 字符串）取决于你，哈哈。

@data = 
(SELECT
    GROUP_CONCAT(combined SEPARATOR ';')
FROM (
    SELECT
        CONCAT(
            '"',
            CONCAT(
                ((CEIL(ratio * 4) * 0.25) - 0.25),
                " - ",
                (CEIL( ratio *4 ) * 0.25)
            ),
            '",',
            COUNT( user )
        ) AS combined
    FROM (
        SELECT
            t1.user,
            t2.ratio
        FROM 
            `table1` t1
        INNER JOIN
            `table2` t2 ON t2.user = t1.user
        GROUP BY
            t1.user
    ) virtual_table
    GROUP BY
        CEIL( ratio *4 )
) virtual_table2 )