Hive sql语句必练50题-入门到精通(3)

承接: Hive sql语句必练50题-入门到精通(2)
– 36、查询任何一门课程成绩在70分以上的学生姓名、课程名称和分数:

select student.s_id,s_name,c_name,s_score from student
  join (select sc.* from score sc
        left join(select s_id from score where s_score < 70 group by s_id)tmp
        on sc.s_id=tmp.s_id where tmp.s_id is null)tmp2
    on student.s_id=tmp2.s_id
  join course on tmp2.c_id=course.c_id
order by s_id;


**-- 查询全部及格的信息**
select sc.* from score sc
  left join(select s_id from score where s_score < 60 group by s_id)tmp
    on sc.s_id=tmp.s_id
where  tmp.s_id is  null;
**-- 或(效率低)**
select sc.* from score sc
where sc.s_id not in (select s_id from score where s_score < 60 group by s_id);

– 37、查询课程不及格的学生:

select s_name,c_name as courseName,tmp.s_score
from student
join (select s_id,s_score,c_name
      from score,course
      where score.c_id=course.c_id and s_score < 60)tmp
on student.s_id=tmp.s_id;

–38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名:

select student.s_id,s_name,s_score as score_01
from student
join score on student.s_id=score.s_id
where c_id='01' and s_score >= 80;

– 39、求每门课程的学生人数:

select course.c_id,course.c_name,count(1)as selectNum
from course
join score on course.c_id=score.c_id
group by course.c_id,course.c_name;

– 40、查询选修"张三"老师所授课程的学生中，成绩最高的学生信息及其成绩:

select student.*,tmp3.c_name,tmp3.maxScore
from (select s_id,c_name,max(s_score)as maxScore from score
      join (select course.c_id,c_name from course join
                  (select t_id,t_name from teacher where t_name='张三')tmp
            on course.t_id=tmp.t_id)tmp2
      on score.c_id=tmp2.c_id group by score.s_id,c_name
      order by maxScore desc limit 1)tmp3
join student
on student.s_id=tmp3.s_id;

– 41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩:

select distinct a.s_id,a.c_id,a.s_score from score a,score b
    where a.c_id <> b.c_id and a.s_score=b.s_score;

– 42、查询每门课程成绩最好的前三名:

select tmp1.* from
  (select *,row_number()over(order by s_score desc) ranking
      from score  where c_id ='01')tmp1
where tmp1.ranking <= 3
union all
select tmp2.* from
  (select *,row_number()over(order by s_score desc) ranking
      from score where c_id ='02')tmp2
where tmp2.ranking <= 3
union all
select tmp3.* from
  (select *,row_number()over(order by s_score desc) ranking
      from score where c_id ='03')tmp3
where tmp3.ranking <= 3;

– 43、统计每门课程的学生选修人数（超过5人的课程才统计）:
– 要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列

select distinct course.c_id,tmp.num from course
    join (select c_id,count(1) as num from score group by c_id)tmp
    where tmp.num>=5 order by tmp.num desc ,course.c_id asc;

– 44、检索至少选修两门课程的学生学号:

select s_id,count(c_id) as totalCourse
from score
group by s_id
having count(c_id) >= 2;

– 45、查询选修了全部课程的学生信息:

select student.* 
from student,
     (select s_id,count(c_id) as totalCourse 
      from score group by s_id)tmp
where student.s_id=tmp.s_id and totalCourse=3;

–46、查询各学生的年龄(周岁):
– 按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
方法一

 select s_name,s_birth,
    	(year(CURRENT_DATE)-year(s_birth)-
    		(case when month(CURRENT_DATE) < month(s_birth) then 1
    			when month(CURRENT_DATE) = month(s_birth) and day(CURRENT_DATE) < day(s_birth) then 1
    			else 0 end)
    	  ) as age
    from student;

方法二:

select s_name,s_birth,
	floor((datediff(current_date,s_birth) - floor((year(current_date) - year(s_birth))/4))/365) as age
from student;

– 47、查询本周过生日的学生:
–方法1

select * from student where weekofyear(CURRENT_DATE)+1 =weekofyear(s_birth);

–方法2

select s_name,s_sex,s_birth from student
    where substring(s_birth,6,2)='10'
    and substring(s_birth,9,2)=14;

– 48、查询下周过生日的学生:
–方法1

select * from student where weekofyear(CURRENT_DATE)+1 =weekofyear(s_birth);

–方法2

select s_name,s_sex,s_birth from student
    where substring(s_birth,6,2)='10'
    and substring(s_birth,9,2)>=15
    and substring(s_birth,9,2)<=21;

– 49、查询本月过生日的学生:
–方法1

select * from student where MONTH(CURRENT_DATE) =MONTH(s_birth);

–方法2

select s_name,s_sex,s_birth from student where substring(s_birth,6,2)='10';

– 50、查询12月份过生日的学生:

select s_name,s_sex,s_birth from student where substring(s_birth,6,2)='12';

所有代码亲测有效!
如果因为hive版本及测试环境造成无法运行的还请自行修正!

hive sql中的部分方法总结:

1.case when ... then ... else ... end

2.length(string)

3.cast(string as bigint)

4.rand()       返回一个0到1范围内的随机数

5.ceiling(double)    向上取整

6.substr(string A, int start, int len)

7.collect_set(col)函数只接受基本数据类型，它的主要作用是将某字段的值进行去重汇总，产生array类型字段

8.concat()函数
	1、功能：将多个字符串连接成一个字符串。
	2、语法：concat(str1, str2,...)
	返回结果为连接参数产生的字符串，如果有任何一个参数为null，则返回值为null。

	9.concat_ws()函数
	1、功能：和concat()一样，将多个字符串连接成一个字符串，但是可以一次性指定分隔符～（concat_ws就是concat with separator）
	2、语法：concat_ws(separator, str1, str2, ...)
	说明：第一个参数指定分隔符。需要注意的是分隔符不能为null，如果为null，则返回结果为null。

	10.nvl(expr1, expr2)：空值转换函数  nvl(x,y)    Returns y if x is null else return x

11.if(boolean testCondition, T valueTrue, T valueFalse)

12.row_number()over()分组排序功能,over()里头的分组以及排序的执行晚于 where group by  order by 的执行。

13.获取年、月、日、小时、分钟、秒、当年第几周
	select 
		year('2018-02-27 10:00:00')       as year
		,month('2018-02-27 10:00:00')      as month
		,day('2018-02-27 10:00:00')        as day
		,hour('2018-02-27 10:00:00')       as hour
		,minute('2018-02-27 10:00:00')     as minute
		,second('2018-02-27 10:00:00')     as second
		,weekofyear('2018-02-27 10:00:00') as weekofyear
  获取当前时间:
		1).current_timestamp
		2).unix_timestamp()
		3).from_unixtime(unix_timestamp())
		4).CURRENT_DATE