群友常见面经整理

方法一：
select count(sex),sex from A where age=25 group by sex

方法二：
select  count(sex),sex  from A  group  by  sex,age having  age = 25;

a = [1, 2, 5, 7]
new_a = []
for i in range(0, len(a)):
    if i == len(a) - 1:
        continue
    else:
        b = a[i] + a[i + 1]
        if b in a:
            continue
        else:
            new_a.append(b)
print(new_a)