这条 SQL 是啥意思呢？ [ 2.0 版本 ]

select 
        a.ins_id,
        b.product_id,
        b.product_name,
        c.cust_id,
        c.cust_name,
        c.cust_sex,
        c.cust_age,
        c.family_num,
        -- 男
        -- 这个地方根据数据库字段的不同，处理方式也不同
        -- 如果数据库中cust_sex的数据类型本身就是0和1，那么就不需要转换
        -- 只列出来即可
        (case when c.cust_sex='男' then 1 else 0 end) as f,
        -- 女
        (case when c.cust_sex='女' then 1 else 0 end) as as m,
        -- 其他的依次类推
        -- 家庭成员数
        (case when c.family_num=1 then 1 else 0 end) as p_1,
        (case when c.family_num=2 then 1 else 0 end) as P_2,
        (case when c.family_num=3 then 1 else 0 end) as p_3,
        (case when c.family_num>3 then 1 else 0 end) as gt3,
        -- 客户年龄
        (case when c.cust_age<=25 then 1 else 0 end) as lt25,
        (case when c.cust_age>25 and c.cust_age<=35 then 1 else 0 end) as gt25lt35,
        (case when c.cust_age>35 and c.cust_age<=45 then 1 else 0 end) as gt35lt45,
        (case when c.cust_age>45 and c.cust_age<=55 then 1 else 0 end) as gt45lt55,
        (case when c.cust_age>55 then 1 else 0 end) as gt55
from
        insurance a,
        product b,
        customer c
where 
        a.product_id=b.product_id
        and a.cust_id=c.cust_id
最后分组count一下即可：
select 
        a.product_id,
        a.product_name,
        count(a.ins_id) as ins_num,
        -- 性别
        count(a.f) as f_num,
        count(a.m) as m_num,
        -- 成员数
        count(a.p_1) as p_1_num,
        count(a.p_2) as p_1_num,
        count(a.p_3) as p_1_num,
        count(a.gt3) as gt3_num,
        -- 年龄
        count(lt25) as lt25_num,
        count(gt25lt35) as gt25lt35_num,
        count(gt35lt45) as gt25lt35_num,
        count(gt45lt55) as gt25lt35_num,
        count(gt55) as gt55_num
from(
        select 
                a.ins_id,
                b.product_id,
                b.product_name,
                c.cust_id,
                c.cust_name,
                c.cust_sex,
                c.cust_age,
                c.family_num,
                -- 男
                -- 这个地方根据数据库字段的不同，处理方式也不同
                -- 如果数据库中cust_sex的数据类型本身就是0和1，那么就不需要转换
                -- 只列出来即可
                (case when c.cust_sex='男' then 1 else 0 end) as f,
                -- 女
                (case when c.cust_sex='女' then 1 else 0 end) as as m,
                -- 其他的依次类推
                -- 家庭成员数
                (case when c.family_num=1 then 1 else 0 end) as p_1,
                (case when c.family_num=2 then 1 else 0 end) as P_2,
                (case when c.family_num=3 then 1 else 0 end) as p_3,
                (case when c.family_num>3 then 1 else 0 end) as gt3,
                -- 客户年龄
                (case when c.cust_age<=25 then 1 else 0 end) as lt25,
                (case when c.cust_age>25 and c.cust_age<=35 then 1 else 0 end) as gt25lt35,
                (case when c.cust_age>35 and c.cust_age<=45 then 1 else 0 end) as gt35lt45,
                (case when c.cust_age>45 and c.cust_age<=55 then 1 else 0 end) as gt45lt55,
                (case when c.cust_age>55 then 1 else 0 end) as gt55
        from
                insurance a,
                product b,
                customer c
        where 
                a.product_id=b.product_id
                and a.cust_id=c.cust_id
) a
group by b.product_id, b.product_name