在Mysql中获取分组后的列的聚合计数

Question

I'm not a strong database person but i have an intermediate knowledge of it. Here is my challenge which I'm facing, I have a table like -

pin  type   day month year timestamp value
---- -----  --- ---   ---  --------  -----
123  clicks 02  12    2014 unixtime  3
123  clicks 03  12    2014 unixtime  7
111  clicks 02  12    2014 unixtime  10

I would like a mysql query that would select all rows that the pin=$pin and month=$month and return all columns with an aggregate count of the value

For the sample dataset above , id like to get something like

pin  type   month year  timestamp value
---- -----  ---   ---   ---       --------  -----
123  clicks 12    2014  unixtime  10

Any help would be appreciated.

Answer 1

You need to use GROUP BY, SUM() and COUNT()

SELECT COUNT(month) as month, SUM(value) AS value
FROM TABLE_NAME 
WHERE pin = '$pin'
AND month='$month' // Added $month in condition
GROUP BY pin, month, year // Added some conditions

Explanation:

You need

1) all rows of pin specified so, used WHERE

2) COUNT of month for the specified pin so used, COUNT()

3) SUM of value for the specified pin so used, SUM()

Answer 2

This could be done as

select
pin,
type,
day,
month,
year,
timestamp,
sum(value) as value 
from table_name
where pin='$pin' and month='$month'
group by pin,month,year

If you do not want the grouping per month then remove it from group by clause and use only year.

Note that the above query is mysql specific. In standard when you select some columns using aggregate function they must appear in he group by clause.