找到最受欢迎的租车工具

Question

我有这张桌子，我需要根据序列号找到最受欢迎的租车工具。

+------------+---------------+
| hire_id | serial_number |
+------------+---------------+
|         1 | 99UU123       |
|         2 | JBB45         |
|         1 | YQE221RR      |
|         3 | UTY1236Y      |
|         4 | YY32RR12      |
|         4 | TRW14         |
|         5 | TRW14         |
|         6 | JBB45         |
+------------+---------------+

输出应为

+------------+---------------+
| most popular| serial_number |
+------------+---------------+
|        2    | JBB45         |
|        2    | TRW14         |
...............................

如何使用SQL命令获取此输出？

Answer 1

使用Group by和having子句

SELECT Count(serial_number) most_popular,
       serial_number
FROM   tablename
GROUP  BY serial_number
HAVING Count(serial_number) = (SELECT Count(serial_number) ss
                               FROM   from tablename
                               GROUP  BY serial_number
                               ORDER  BY ss DESC LIMIT 1) 

Answer 2

以下查询将有效

SELECT   COUNT(serial_number) AS `most_popular`, serial_number 
FROM     your_table_name
GROUP BY serial_number
ORDER BY most_popular DESC
LIMIT    2;