[英]Count occurrences of distinct values in 2 fields
I am trying to find a MySQL query that will find distinct values in a particular field, count the number of occurrences of that value in 2 fields (1_user, 2_user) and then order the results by the count. 我试图找到一个MySQL查询,它将在特定字段中找到不同的值,计算2个字段(1_user,2_user)中该值的出现次数,然后按计数对结果进行排序。
example db 示例db
+------+-----------+-----------+ | id | 1_user | 2_user | +------+-----------+-----------+ | 1 | 2 | 1 | | 2 | 3 | 2 | | 3 | 8 | 7 | | 4 | 1 | 8 | | 5 | 2 | 8 | | 6 | 3 | 8 | +------+-----------+-----------+
expected result 预期结果
user count ----- ----- 8 4 2 3 3 2 1 2
The Query 查询
SELECT user, count(*) AS count
FROM
(
SELECT 1_user AS USER FROM test
UNION ALL
SELECT 2_user FROM test
) AS all_users
GROUP BY user
ORDER BY count DESC
Explanation 说明
List all the users in the first column. 列出第一列中的所有用户。
SELECT 1_user AS USER FROM test
Combine them with the users from the second column. 将它们与第二列中的用户组合。
UNION ALL
SELECT 2_user FROM test
The trick here is the UNION ALL which preserves duplicate values. 这里的技巧是UNION ALL保留重复值。
The rest is easy -- select the results you want from the subquery: 其余很简单 - 从子查询中选择所需的结果:
SELECT user, count(*) AS count
aggregate by user: 用户聚合:
GROUP BY user
and prescribe the order: 并订明订单:
ORDER BY count DESC
SELECT u, count(u) AS cnt
FROM (
SELECT 1_user AS u FROM table
UNION ALL
SELECT 2_user AS u FROM table
) subquery
GROUP BY u
ORDER by cnt DESC
Take the 2 queries: 拿2个查询:
SELECT COUNT(*) FROM table GROUP BY 1_user
SELECT COUNT(*) FROM table GROUP BY 2_user
Now combine them: 现在结合它们:
SELECT user, SUM(count) FROM
((SELECT 1_user as user FROM table)
UNION ALL
(SELECT 2_user as user FROM table))
GROUP BY user, ORDER BY count DESC;
I think this what you are looking for since your expected result did not include 7
我认为这是你正在寻找的,因为你的预期结果不包括7
select usr, count(usr) cnt from
(
select user_1 usr from users
union all
select user_2 usr from users
) u
where u.usr in (select user_1 from users)
group by usr
order by count(u.usr) desc
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