SQL最频繁的值取决于另一个值

Question

I'm using SQL*Plus and i need some help. I have 1 table with tons of information of different cars with different drivers.

What i want to find is the most frequent driver for each car plate . I have the CAR_PLATE and DRIVER values. I've been trying to use group by and count , but I haven't been able to do it.

TEBLE (
..OTHER VALUES
DRIVER
CAR_PLATE
)

The data in it adds tons of different cars with different drivers but some repeat.

Answer 1

the most frequent driver for each car plate

This tells you that you need to group by CAR_PLATE and need the count of DRIVER . Since you need the count of DRIVER driver also needs to be in the group by clause. Since you want the most frequent one, you will also need to order by on the count.

SELECT
  CAR_PLATE,
  DRIVER,
  count(DRIVER) AS driver_count
FROM tableName
GROUP BY CAR_PLATE, DRIVER
ORDER BY driver_count DESC;

Here is an SQL fiddle to play with: http://sqlfiddle.com/#!15/d08ea/4