MYSQL 用多行划分多个子查询的结果

Question

我有两个查询，第一个生成 table 喜欢

SELECT COUNT(channel) AS messages FROM Chats WHERE message LIKE '%word%' GROUP BY UNIX_TIMESTAMP(time) DIV 3600
+-----+
| 123 |
| 127 |
| 332 |
| 219 |
+-----+

和第二个

SELECT COUNT(channel) AS messages FROM Chats GROUP BY UNIX_TIMESTAMP(time) DIV 3600
+-----+
| 222 |
| 579 |
| 590 |
| 377 |
+-----+

现在我想用第一个 table 的所有结果除以第二个的相应值（结果四舍五入，必须手动计算）：

+------+
| 0.55 | #123/222
| 0.46 | #127/279
| 0.56 | #332/590
| 0.58 | #219/377
+------+

Answer 1

这是您可以通过以下查询完成整个事情的一种方法：

SELECT 
(dividendTable.messages / divisorTable.messages) AS result
FROM
(
    SELECT 
    firstTable.messages,
    @rn1 := @rn1 + 1 AS row_number
    FROM 
    (
        SELECT
            COUNT(channel) AS messages
        FROM Chats
        WHERE   message LIKE '%word%'
        GROUP BY    UNIX_TIMESTAMP(time) DIV 3600
    ) FirstTable, (SELECT @rn1 := 0) var1
) AS dividendTable
INNER JOIN
(   
    SELECT 
    secondTable.messages,
    @rn2 := @rn2 + 1 AS row_number
    FROM
    (
        SELECT 
            COUNT(channel) AS messages 
        FROM Chats 
        GROUP BY UNIX_TIMESTAMP(time) DIV 3600
    ) secondTable, (SELECT @rn2 := 0) var2
) AS divisorTable
ON dividendTable.row_number = divisorTable.row_number;

注：

如果您希望结果四舍五入到小数点后 2 位，则使用以下内容作为查询的第一行：

SELECT
ROUND((dividendTable.messages / divisorTable.messages),2) AS result

Demo Here

注意：您没有在查询中使用任何 ORDER BY。您可能会遇到随机行为。

MYSQL 用多行划分多个子查询的结果

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