Hive sql語句必練50題-入門到精通(3)
原始鏈接：https://blog.csdn.net/Thomson617/article/details/83281254
原創Thomson617 最後發佈於2018-10-23 00:50:59 閱讀數 1945 收藏
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承接: Hive sql語句必練50題-入門到精通(2)
– 36、查詢任何一門課程成績在70分以上的學生姓名、課程名稱和分數:
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;
**-- 查詢全部及格的信息**
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);
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– 37、查詢課程不及格的學生:
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;
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–38、查詢課程編號爲01且課程成績在80分以上的學生的學號和姓名:
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;
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– 39、求每門課程的學生人數:
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;
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– 40、查詢選修"張三"老師所授課程的學生中，成績最高的學生信息及其成績:
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='張三')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;
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– 41、查詢不同課程成績相同的學生的學生編號、課程編號、學生成績:
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;
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– 42、查詢每門課程成績最好的前三名:
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;
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– 43、統計每門課程的學生選修人數（超過5人的課程才統計）:
– 要求輸出課程號和選修人數，查詢結果按人數降序排列，若人數相同，按課程號升序排列
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;
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– 44、檢索至少選修兩門課程的學生學號:
select s_id,count(c_id) as totalCourse
from score
group by s_id
having count(c_id) >= 2;
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– 45、查詢選修了全部課程的學生信息:
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;
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–46、查詢各學生的年齡(週歲):
– 按照出生日期來算，當前月日 < 出生年月的月日則，年齡減一
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;
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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;
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– 47、查詢本週過生日的學生:
–方法1
select * from student where weekofyear(CURRENT_DATE)+1 =weekofyear(s_birth);
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–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;
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– 48、查詢下週過生日的學生:
–方法1
select * from student where weekofyear(CURRENT_DATE)+1 =weekofyear(s_birth);
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–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;
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– 49、查詢本月過生日的學生:
–方法1
select * from student where MONTH(CURRENT_DATE) =MONTH(s_birth);
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–方法2
select s_name,s_sex,s_birth from student where substring(s_birth,6,2)='10';
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– 50、查詢12月份過生日的學生:
select s_name,s_sex,s_birth from student where substring(s_birth,6,2)='12';
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所有代碼親測有效!
如果因爲hive版本及測試環境造成無法運行的還請自行修正!
hive sql中的部分方法總結:
1.case when ... then ... else ... end
2.length(string)
3.cast(string as bigint)
4.rand() 返回一個0到1範圍內的隨機數
5.ceiling(double) 向上取整
6.substr(string A, int start, int len)
7.collect_set(col)函數只接受基本數據類型，它的主要作用是將某字段的值進行去重彙總，產生array類型字段
8.concat()函數
1、功能：將多個字符串連接成一個字符串。
2、語法：concat(str1, str2,...)
返回結果爲連接參數產生的字符串，如果有任何一個參數爲null，則返回值爲null。
9.concat_ws()函數
1、功能：和concat()一樣，將多個字符串連接成一個字符串，但是可以一次性指定分隔符～（concat_ws就是concat with separator）
2、語法：concat_ws(separator, str1, str2, ...)
說明：第一個參數指定分隔符。需要注意的是分隔符不能爲null，如果爲null，則返回結果爲null。
10.nvl(expr1, expr2)：空值轉換函數 nvl(x,y) Returns y if x is null else return x
11.if(boolean testCondition, T valueTrue, T valueFalse)
12.row_number()over()分組排序功能,over()裏頭的分組以及排序的執行晚於 where group by order by 的執行。
13.獲取年、月、日、小時、分鐘、秒、當年第幾周
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
獲取當前時間:
1).current_timestamp
2).unix_timestamp()
3).from_unixtime(unix_timestamp())
4).CURRENT_DATE