经典Hive SQL面试题

第一题

需求

我们有如下的用户访问数据
	userId  visitDate   visitCount
	u01 2017/1/21   5
	u02 2017/1/23   6
	u03 2017/1/22   8
	u04 2017/1/20   3
	u01 2017/1/23   6
	u01 2017/2/21   8
	U02 2017/1/23   6
	U01 2017/2/22   4
要求使用SQL统计出每个用户的累积访问次数，如下表所示：
	用户id    月份  小计  累积
	u01 2017-01 11  11
	u01 2017-02 12  23
	u02 2017-01 12  12
	u03 2017-01 8   8
	u04 2017-01 3   3

实现

数据准备

CREATE TABLE test_sql.test1 ( 
		userId string, 
		visitDate string,
		visitCount INT )
	ROW format delimited FIELDS TERMINATED BY "\t";
	INSERT INTO TABLE test_sql.test1
	VALUES
		( 'u01', '2017/1/21', 5 ),
		( 'u02', '2017/1/23', 6 ),
		( 'u03', '2017/1/22', 8 ),
		( 'u04', '2017/1/20', 3 ),
		( 'u01', '2017/1/23', 6 ),
		( 'u01', '2017/2/21', 8 ),
		( 'u02', '2017/1/23', 6 ),
		( 'u01', '2017/2/22', 4 );

查询SQL

SELECT t2.userid,
	   t2.visitmonth,
	   subtotal_visit_cnt,
	   sum(subtotal_visit_cnt) over (partition BY userid
									 ORDER BY visitmonth) AS total_visit_cnt
FROM
  (SELECT userid,
		  visitmonth,
		  sum(visitcount) AS subtotal_visit_cnt
   FROM
	 (SELECT userid,
			 date_format(regexp_replace(visitdate,'/','-'),'yyyy-MM') AS visitmonth,
			 visitcount
	  FROM test_sql.test1) t1
   GROUP BY userid,
			visitmonth)t2
ORDER BY t2.userid,
		 t2.visitmonth

第二题

需求

有50W个京东店铺，每个顾客访客访问任何一个店铺的任何一个商品时都会产生一条访问日志，
访问日志存储的表名为Visit，访客的用户id为user_id，被访问的店铺名称为shop，数据如下：

				u1	a
				u2	b
				u1	b
				u1	a
				u3	c
				u4	b
				u1	a
				u2	c
				u5	b
				u4	b
				u6	c
				u2	c
				u1	b
				u2	a
				u2	a
				u3	a
				u5	a
				u5	a
				u5	a
请统计：
(1)每个店铺的UV（访客数）
(2)每个店铺访问次数top3的访客信息。输出店铺名称、访客id、访问次数

实现

数据准备

CREATE TABLE test_sql.test2 ( 
						 user_id string, 
						 shop string )
			ROW format delimited FIELDS TERMINATED BY '\t';	
			INSERT INTO TABLE test_sql.test2 VALUES
			( 'u1', 'a' ),
			( 'u2', 'b' ),
			( 'u1', 'b' ),
			( 'u1', 'a' ),
			( 'u3', 'c' ),
			( 'u4', 'b' ),
			( 'u1', 'a' ),
			( 'u2', 'c' ),
			( 'u5', 'b' ),
			( 'u4', 'b' ),
			( 'u6', 'c' ),
			( 'u2', 'c' ),
			( 'u1', 'b' ),
			( 'u2', 'a' ),
			( 'u2', 'a' ),
			( 'u3', 'a' ),
			( 'u5', 'a' ),
			( 'u5', 'a' ),
			( 'u5', 'a' );			

查询SQL实现

(1)方式1：
		SELECT shop,
			   count(DISTINCT user_id)
		FROM test_sql.test2
		GROUP BY shop
方式2：
		SELECT t.shop,
			   count(*)
		FROM
		  (SELECT user_id,
				  shop
		   FROM test_sql.test2
		   GROUP BY user_id,
					shop) t
		GROUP BY t.shop
(2)	
SELECT t2.shop,
	   t2.user_id,
	   t2.cnt
FROM
  (SELECT t1.*,
		  row_number() over(partition BY t1.shop
							ORDER BY t1.cnt DESC) rank
   FROM
	 (SELECT user_id,
			 shop,
			 count(*) AS cnt
	  FROM test_sql.test2
	  GROUP BY user_id,
			   shop) t1)t2
WHERE rank <= 3					

第三题

需求

已知一个表STG.ORDER，有如下字段:Date，Order_id，User_id，amount。
数据样例:2017-01-01,10029028,1000003251,33.57。
请给出sql进行统计:
(1)给出 2017年每个月的订单数、用户数、总成交金额。
(2)给出2017年11月的新客数(指在11月才有第一笔订单)

实现

数据准备

CREATE TABLE test_sql.test3 ( 
			dt string,
			order_id string, 
			user_id string, 
			amount DECIMAL ( 10, 2 ) )
ROW format delimited FIELDS TERMINATED BY '\t';
INSERT INTO TABLE test_sql.test3 VALUES ('2017-01-01','10029028','1000003251',33.57);
INSERT INTO TABLE test_sql.test3 VALUES ('2017-01-01','10029029','1000003251',33.57);
INSERT INTO TABLE test_sql.test3 VALUES ('2017-01-01','100290288','1000003252',33.57);
INSERT INTO TABLE test_sql.test3 VALUES ('2017-02-02','10029088','1000003251',33.57);
INSERT INTO TABLE test_sql.test3 VALUES ('2017-02-02','100290281','1000003251',33.57);
INSERT INTO TABLE test_sql.test3 VALUES ('2017-02-02','100290282','1000003253',33.57);
INSERT INTO TABLE test_sql.test3 VALUES ('2017-11-02','10290282','100003253',234);
INSERT INTO TABLE test_sql.test3 VALUES ('2018-11-02','10290284','100003243',234);

查询SQL

(1)
SELECT t1.mon,
	   count(t1.order_id) AS order_cnt,