Question

如果找到目的地，我如何找到最常见的航班类型？

Table: Flight:
+-------------+---------------+
| Destination | Type          |
+-------------+---------------+
| Beijing     | First Class   |
| Beijing     | First Class   |
| Beijing     | First Class   |
| Beijing     | First Class   |
| Beijing     | Coach         |
| London      | Coach         |
| London      | First Class   |
| London      | Coach         |
+-------------+---------------+

到目前为止，我所尝试的每个查询都给出了每种航班类型的总数，而不是每个目的地的最常见航班类型。

这是所需的输出：

+-------------+--------------+-------+
| Destination | Type         | count |
+-------------+--------------+-------+
| Beijing     | First Class  |     4 |
| London      | Coach        |     2 |
+-------------+--------------+-------+

编辑：所以我发现最简单的方法就是：

SELECT destination, type, count FROM Flight WHERE total=
(
SELECT MAX(total) FROM Flight fl WHERE fl.destination = Flight.destination
);

Answer 1

您可以尝试GROUP BY和HAVING。您必须为每个组（MAX）选择总行数为Destination, Type的行。

SELECT Destination, `Type`, COUNT(*) AS total
FROM your_table AS aa
GROUP BY Destination, `Type`
HAVING COUNT(*) = (
    SELECT MAX(each_total) 
    FROM (
        SELECT COUNT(*) AS each_total
        FROM your_table
        GROUP BY Destination, `Type`
    )
)
ORDER BY Destination ASC;

MYSQL给定某一类别的最频繁值

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