Simple SQL statement Statistics monthly data per month for each column of data, simple SQL exercise

There is a table with the following data

Please write the SQL statement with the result as follows.

Create a table in MySQL

CREATE TABLE ' AA ' (
' id ' int (ten) not NULL auto_increment COMMENT ' book Number ',
' Year ' varchar (4) is not NULL DEFAULT ' COMMENT ',
' Month ' varchar (2) Not NULL DEFAULT ' 0 ' COMMENT ' month ',
' Mount ' double DEFAULT NULL COMMENT ' quantity ',
PRIMARY KEY (' id ')
) Engine=innodb DEFAULT Charset=utf8;

Insert data:

INSERT into AA (Year,month,mount) VALUES (2011,1,1.1), (2011,2,1.2), (2011,3,1.3), (2011,4,1.4);
INSERT into AA (Year,month,mount) VALUES (2012,1,2.1), (2012,2,2.2), (2012,3,2.3), (2012,4,2.4);
INSERT into AA (Year,month,mount) VALUES (2013,1,3.1), (2013,2,3.2), (2013,3,3.3), (2013,4,3.4);
INSERT into AA (Year,month,mount) VALUES (2014,1,4.1), (2014,2,4.2), (2014,3,4.3), (2014,4,4.4);

The query statements are:

Select T2.year, (select T1.mount from AA t1 where t1.year = t2.year and T1.month = 1) M1,
(select T1.mount from AA t1 where t1.year = t2.year and t1.month = 2) m2,
(select T1.mount from AA t1 where t1.year = t2.year and t1.month = 3) M3,
(select T1.mount from the AA t1 where t1.year = t2.year and T1.month = 4) M4 from
AA T2 GROUP BY t2.year Order by T2.year;

Complete.

Note: Simple implementation of a bit, if you have a better, if it is convenient to share, if anything wrong, please point out, thank you!

Simple SQL statement Statistics monthly data per month for each column of data, simple SQL exercise