Question

我有一个包含这样数据的表：

event | session id | uid 
---------------------
foo   | 1          | a
bar   | 1          | a
foo   | 2          | b
cat   | 2          | b
cat   | 3          | a
cat   | 4          | c
foo   | 5          | c
cat   | 5          | c
foo   | 6          | b
foo   | 7          | a
dog   | 8          | c
dog   | 9          | b
bat   | 10         | c

我想创建一个查询以按以下格式返回结果：

uid | event | # event used | # of sessions for uid
a   | foo   | 2            | 4 
a   | bar   | 1            | 4
a   | cat   | 1            | 4
b   | foo   | 2            | 4
b   | cat   | 1            | 4
b   | dog   | 1            | 4
c   | cat   | 2            | 5
c   | foo   | 1            | 5
c   | dog   | 1            | 5
c   | bat   | 1            | 5

我尝试使用：

select uid, event, count(*) from events where uid in (select uid from events group by uid) group by uid;

但是没有按预期工作。

非常感谢任何帮助。

Answer 1

select t1.uid, t1.event, count(*) as `# event used`, t2.total_events as `# of sessions for uid`
form table t1
inner join (
   select uid, count(*) as total_events
   from table
   group by uid
) t2 on t2.uid = a.uid
group by t1.uid, t1.event, t2.total_events
order by t1.uid, `# event used` desc

Answer 2

这可以通过 CASE 语句来实现：

select uid,  count(case when event=`foo` then uid else 0 end)  as `foo`,   
count(case when    event=`bar` then uid else 0 end)  as `bar`,  
count(case when event=`cat` then uid else 0 end)  as `cat`, 
count((case when event=`foo` then uid else 0 end) +  count(case when    event=`bar` then uid else 0 end) + count(case when event=`cat` then uid else 0 end))  as totaL_events` 
from  events group by 1;

这会给你一个这样的表：

uid | foo | bar | cat | total_events
a     2     1     1       4
b     2     1     1       4

对于其他表，请使用：

select uid, event, count(uid) as event_used  from events group by 1, 2

这里的表格不那么花哨：

uid | event | total_events
a     foo     2     
a     bar     1   
b     foo     2

请记住，根据您的要求，总结每个用户在每个不同情况下的事件总数是不可能或最不高效的，只需通过uid和事件类型即可实现。

需要帮助创建查询以总结表中出现的次数

2 个答案: