运算符：数学运算符

mysql> select class,number,maths,maths+5 from score;

mysql>select class,number,chinese+maths+english from score;

mysql> select *,maths+chinese+english as total from score;

mysql> select *,maths+chinese+english as total from score order by total desc;

mysql> select class*2,number,maths+chinese+english as total from score order by total desc;