SQL在一个列中计算最常用的值，其中另一列等于某值。

Question

This is a bit of a weird one I didn't know how to word the title please bear with me.

So I have a table like this which stores data on different jobs:

id | company | contact
----------------------
0  |  name1  |  Bob
1  |  name1  |  Mark
2  |  name3  |  Sam
3  |  name1  |  Bob
4  |  name2  |  Nigel
5  |  name1  |  Bob
6  |  name3  |  Donald
7  |  name1  |  Sandy
8  |  name3  |  Nigel

Is there a query with SQL I can use to query the table to find out the most commonly used contact for a particular company.

So the theoretical code I would be looking for would be something like:

SELECT "Most Commonly used Contact" FROM table WHERE company = "$company";   

Is it possible in a single query or is this a multi query job?

Answer 1

try this sql query...

SELECT *, COUNT(*) AS total 
FROM table 
WHERE company = '$company'
GROUP BY contact 
ORDER BY total DESC
LIMIT 1

Answer 2

Basically you want to find the number of contacts grouped by each company, and then grouped by the actual contact. So in other words:

SELECT COUNT(`id`) as num_contacts, `contact`, `company` FROM `jobtable` GROUP BY `company`, `contact` ORDER BY `company`, num_contacts DESC

Or for a single company:

SELECT COUNT(`id`) as num_contacts, `contact` FROM `jobtable` WHERE `company`='$company' GROUP BY `contact` ORDER BY num_contacts DESC

Answer 3

Gives you the single most used contact for $company, if you can't use LIMIT (eg if you are utilizing an Oracle Database):

SELECT contact, used_by
FROM (
  SELECT contact, COUNT(*) AS used_by
  FROM table
  WHERE company = $company
  GROUP BY contact
) t
HAVING used_by = MAX(used_by)