DROP TABLE IF EXISTS sales;CREATE TABLE sales(    id INT NOT NULL AUTO_INCREMENT,    YEAR VARCHAR(4),    MONTH VARCHAR(2),    amount FLOAT(2,1),    PRIMARY KEY(id));INSERT INTO sales VALUES    (NULL,"1991","1",1.1),    (NULL,"1991","2",1.2),    (NULL,"1991","3",1.3),    (NULL,"1991","4",1.4),    (NULL,"1992","1",1.1),    (NULL,"1992","2",1.2),    (NULL,"1992","3",1.3),    (NULL,"1992","4",1.4);

SELECT sales.year ,(SELECT t.amount FROM sales t WHERE t.month=‘1‘ AND t.year= sales.year) ‘1‘,(SELECT t.amount FROM sales t WHERE t.month=‘2‘ AND t.year= sales.year) ‘2‘,(SELECT t.amount FROM sales t WHERE t.month=‘3‘ AND t.year= sales.year) ‘3‘,(SELECT t.amount FROM sales t WHERE t.month=‘4‘ AND t.year= sales.year) AS ‘4‘FROM sales GROUP BY YEAR;