針對字符型數字按int排序

1. 針對字符型數字按int降序排序

Mysql三種辦法：

1. 在排序字段前加上-號，轉爲int型負數，排序

   SELECT * FROM  Student WHERE 1 = 1 ORDER BY -age asc;

2. 對排序字段作數學運算，如 +1，

   SELECT * FROM  Student WHERE 1 = 1 ORDER BY (age + 1) desc ;

3. 先對位數排序，在對數字排序

   select * from Student order by length(age) desc,age desc;