crate table grade ( username varchar(45) not null , cource varchar(45) null , score int null);/*插入數據*/
insert into grade (`username`, `cource`, `score`) values ('admin', 'english', '80');
insert into grade (`username`, `cource`, `score`) values ('admin', 'math', '90');
insert into grade (`username`, `cource`, `score`) values ('maco', 'english', '85');
insert into grade (`username`, `cource`, `score`) values ('admin', 'chinese', '85');
insert into grade (`username`, `cource`, `score`) values ('maco', 'math', '70');
insert into grade (`username`, `cource`, `score`) values ('maco', 'chinese', '68');
select * from grade;
/*查詢行列轉換結果*/
select username,
sum(if(cource='chinese',score,0)) as chinese,
sum(if(cource='math',score,0)) as math,
sum(if(cource='english',score,0)) as english from grade group by username;
