从连接MySQL中其他表的两个不同的列中获取平均值

Question

I have the following table in mySQL with sample data:

Table1 :

id    type    locid    month    qty
1     car1      1      JAN       2
2     car1      1      FEB       1
3     car1      2      JAN       3
4     car1      2      MAR       2
5     car2      1      FEB       2
6     car2      1      MAY       5

Table2 :

id    location
1        CA
2        NY

I have difficulty in getting the average of the quantity from this distinct two columns which is the type and the location. Would it be possible to compute the average with in the past 3 months only?

Here is the result I would like to accomplish:

type      CA_AVE      NY_AVE
-----------------------------
car1        1.5         2.5
car2        2  <-- assumed the current month is MARCH so the qty for MAY should 
                   not be included to get the average

Answer 1

This is your answer. but you should conside now month is aug not march b/ci used now(). okey. so change your table data accordingly and check the result.

select AVG( loc) as loc,AVG(qty) as qty from tbl1  where month NOT IN (concat(UCASE(DATE_FORMAT(date_add(now(), INTERVAL -1 MONTH),'%b')),',',
         UCASE(DATE_FORMAT(date_add(now(), INTERVAL -2 MONTH),'%b')),',',
         UCASE(DATE_FORMAT(date_add(now(), INTERVAL -3 MONTH),'%b')))) group by type

For DEMO Click here:- http://sqlfiddle.com/#!2/2a15e/15