diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 0000000..c13239c
Binary files /dev/null and b/.DS_Store differ
diff --git a/Week1/.DS_Store b/Week1/.DS_Store
index 9411341..f8b0039 100644
Binary files a/Week1/.DS_Store and b/Week1/.DS_Store differ
diff --git a/Week1/solutions/.DS_Store b/Week1/solutions/.DS_Store
new file mode 100644
index 0000000..18a4cfd
Binary files /dev/null and b/Week1/solutions/.DS_Store differ
diff --git a/Week1/solutions/hw1_dorzhiev_ardan/coffeshop.sh b/Week1/solutions/hw1_dorzhiev_ardan/coffeshop.sh
new file mode 100644
index 0000000..a4a5efe
--- /dev/null
+++ b/Week1/solutions/hw1_dorzhiev_ardan/coffeshop.sh
@@ -0,0 +1,67 @@
+echo 'Welcome to the Dave Coffeeshop!'
+
+if [ -f davecoffeeshop.db ]; then 
+ echo 'davecoffeeshop.db exists, using existing database'
+else
+ echo 'davecoffeeshop.db not exists => creating db file'
+ touch davecoffeeshop.db
+
+ echo 'success' 
+fi
+
+echo 'To log order, enter LOG
+To end session, enter EOS
+To end business day, enter EOD'
+
+while read command
+ do 
+  if [ $command = 'LOG' ]; then 
+   echo 'Enter Barista' 
+   read barista
+   echo 'Enter Drink'
+   read in_drink
+   echo "Barista name: $barista"
+   echo "Drinking: $in_drink"
+   
+   case $in_drink in
+     "AME")
+          price=100
+          ;;
+     "ESP")
+          price=120
+          ;;
+     "CAP")
+          price=150
+          ;;
+     "LAT")
+          price=170
+          ;;
+     "RAF")
+          price=200
+          ;;
+         *)
+	  price=0
+          ;;
+   esac
+   
+   if (( price > 0 )); then    
+    echo "$barista;$in_drink;$price" >> davecoffeeshop.db
+    echo 'Order was saved!'
+   else
+    echo Invalid drink c, ignoring
+   fi
+   
+  elif [ $command = 'EOS' ]; then
+   echo 'End of Session' 
+   exit
+  elif [ $command = 'EOD' ]; then
+   echo 'End of Day!'
+   
+   cat davecoffeeshop.db | sort -nk1 -t ";" | awk -F";" 'BEGIN {OFS=";" }\
+   ($1 == last || last == "") {sum += $3} ($1 != last && last != "")\
+   {print last, sum; sum = $3} {last = $1} END {print last, sum}' | sort -nrk2 -t ";" 
+
+  else 
+   echo 'WRONG COMMAND. USE ONLY LOG, EOD, EOS'
+  fi
+done
diff --git a/Week1/solutions/hw1_dorzhiev_ardan/davecoffeeshop.db b/Week1/solutions/hw1_dorzhiev_ardan/davecoffeeshop.db
new file mode 100644
index 0000000..6712c05
--- /dev/null
+++ b/Week1/solutions/hw1_dorzhiev_ardan/davecoffeeshop.db
@@ -0,0 +1,4 @@
+ARDAN;AME;100
+MARIE;RAF;200
+ARDAN;CAP;150
+MARIE;LAT;170
diff --git "a/Week1/solutions/hw1_dorzhiev_ardan/\320\222\321\213\320\262\320\276\320\264 \321\202\320\265\321\200\320\274\320\270\320\275\320\260\320\273\320\260 DaveCoffeeShop" "b/Week1/solutions/hw1_dorzhiev_ardan/\320\222\321\213\320\262\320\276\320\264 \321\202\320\265\321\200\320\274\320\270\320\275\320\260\320\273\320\260 DaveCoffeeShop"
new file mode 100644
index 0000000..8dd2e0f
--- /dev/null
+++ "b/Week1/solutions/hw1_dorzhiev_ardan/\320\222\321\213\320\262\320\276\320\264 \321\202\320\265\321\200\320\274\320\270\320\275\320\260\320\273\320\260 DaveCoffeeShop"	
@@ -0,0 +1,59 @@
+(base) MacBook-Air-Ardan:~ ardandorzhiev$ sh ./coffeshop.sh
+Welcome to the Dave Coffeeshop!
+davecoffeeshop.db not exists => creating db file
+success
+To log order, enter LOG
+To end session, enter EOS
+To end business day, enter EOD
+LOG
+Enter Barista
+ARDAN
+Enter Drink
+AME
+Barista name: ARDAN
+Drinking: AME
+Order was saved!
+LOG
+Enter Barista
+MARIE
+Enter Drink
+RAF
+Barista name: MARIE
+Drinking: RAF
+Order was saved!
+LOG
+Enter Barista
+ARDAN
+Enter Drink
+CAP
+Barista name: ARDAN
+Drinking: CAP
+Order was saved!
+LOG
+Enter Barista
+NICK
+Enter Drink
+COLA
+Barista name: NICK
+Drinking: COLA
+Invalid drink c, ignoring
+LOG
+Enter Barista
+MARIE
+Enter Drink
+LAT
+Barista name: MARIE
+Drinking: LAT
+Order was saved!
+EOD
+End of Day!
+MARIE;370
+ARDAN;250
+EOS 
+End of Session
+(base) MacBook-Air-Ardan:~ ardandorzhiev$ cat davecoffeeshop.db
+ARDAN;AME;100
+MARIE;RAF;200
+ARDAN;CAP;150
+MARIE;LAT;170
+(base) MacBook-Air-Ardan:~ ardandorzhiev$ 
diff --git a/Week3/.DS_Store b/Week3/.DS_Store
new file mode 100644
index 0000000..66cda8f
Binary files /dev/null and b/Week3/.DS_Store differ
diff --git a/Week3/solutions/.DS_Store b/Week3/solutions/.DS_Store
new file mode 100644
index 0000000..43dab89
Binary files /dev/null and b/Week3/solutions/.DS_Store differ
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task1.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task1.sql
new file mode 100644
index 0000000..a7af359
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task1.sql
@@ -0,0 +1,24 @@
+/* Вывести все альбомы со средней длинной трека, большей 250 секунд. 
+ * Вывести название альбома и количество треков. (album_name, cnt).*/
+
+
+with album_track_length as (select a.album_id 
+								 , a.title as album_name
+						         , round(avg(t.milliseconds)/1000,0) avg_track_length_in_seconds
+						    from album a 
+						    join track t on a.album_id = t.album_id 
+						group by a.album_id 
+							   , a.title 
+						  having avg(t.milliseconds)/1000 > 250
+						order by a.album_id )
+						
+select a.title as album_name
+	, count(t.track_id) cnt
+  from album a 
+  join track t on a.album_id = t.album_id 
+ where exists (select 1 from album_track_length atl where atl.album_id = a.album_id)
+ group by a.album_id
+ 		, a.title 
+ order by a.title 
+
+
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task10.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task10.sql
new file mode 100644
index 0000000..fe6cc33
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task10.sql
@@ -0,0 +1,76 @@
+/* Для каждого альбома тип медиа определяется как наибольшая суммарный размер треков по жанру. 
+ * Для каждого исполнителя вывести тип медиа, соответствующий наибольшему количеству типов медиа по альбомам, где они участвуют.
+ * Вывести имя исполнителя, тип медиа, количество альбомов с данными типом, общее количество альбомов. 
+ * 
+ * (artist_name, media_type_name, media_cnt, whole_cnt)
+ * 
+ * */
+
+
+with album_agg as (select a.album_id 
+					 , t.media_type_id 
+					 , sum(t.bytes) size_tracks
+				  from album a 
+				  join track t on t.album_id = a.album_id 
+				  group by a.album_id 
+					 	 , t.media_type_id
+				  order by a.album_id 
+		        ) ,
+	album_media as (select a1.album_id
+						 , a1.media_type_id
+					  from album_agg a1
+					  join album a on a1.album_id = a.album_id 
+					  where (a1.album_id, a1.media_type_id) in (select a2.album_id, a2.media_type_id
+					  										      from album_agg a2 
+					  						   					 where a1.album_id = a2.album_id
+					  						   					   and a1.media_type_id = a2.media_type_id 
+					  						   				  order by a2.size_tracks desc 
+					  						   					 limit 1 
+					  										     )			      
+					  					      
+					  					      
+				   ) , 
+				   
+	artist_albums_media as (	select a.artist_id
+								 , am.media_type_id
+								 , count(distinct al.album_id) cnt_albums 
+						      from artist a 
+							  join album al on al.album_id = a.artist_id 
+							  join album_media am on al.album_id = am.album_id 
+							  group by a.artist_id
+								 	 , am.media_type_id
+						) ,
+						
+	artist_cnt_media as (select ar.artist_id
+							  , m.media_type_id
+							  , count(distinct a.album_id) cnt_media_albums
+	   					   from album a
+	   					   join album_media m on a.album_id = m.album_id
+	   					   join artist ar on a.artist_id = ar.artist_id 
+	   				   group by ar.artist_id
+							  , m.media_type_id
+						) ,
+						
+	artist_cnt_albums as (select ar.artist_id
+							  , count(distinct a.album_id) cnt_albums 
+	   					   from album a
+	   					   join artist ar on a.artist_id = ar.artist_id 
+	   				   group by ar.artist_id
+						) 						
+						
+						
+ select a."name" as artist_name
+ 	  , mt."name" as media_type_name
+ 	  , acm.cnt_media_albums as media_cnt
+ 	  , aca.cnt_albums as whole_cnt
+   from artist_albums_media am 
+   join artist_cnt_media acm on am.artist_id = acm.artist_id
+   join artist_cnt_albums aca on am.artist_id = aca.artist_id
+   join artist a on am.artist_id = a.artist_id 
+   join media_type mt on am.media_type_id = mt.media_type_id 
+  where am.cnt_albums in (select max(am1.cnt_albums) c 
+                            from artist_albums_media am1
+                           where am1.artist_id = am.artist_id) 
+                           
+  
+	
\ No newline at end of file
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task2.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task2.sql
new file mode 100644
index 0000000..bc1090a
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task2.sql
@@ -0,0 +1,17 @@
+/* Для каждого набора жанр, тип медиа вывести количество треков.
+ * Если для набора жанр, тип медиа треков нет, то такой набор выводить не требуется. 
+ * (genre_name, media_type_name, cnt) 
+ */
+
+  select g."name" as genre_name
+       , mt."name" as media_type_name
+       , count(t.track_id) as cnt_tracks
+    from track t
+    join media_type mt on t.media_type_id = mt.media_type_id 
+    join genre g on t.genre_id = g.genre_id 
+group by g.genre_id
+       , g."name" 
+       , mt.media_type_id 
+       , mt."name" 
+  having count(t.track_id) > 0 
+order by g."name"  
\ No newline at end of file
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task3.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task3.sql
new file mode 100644
index 0000000..90cd460
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task3.sql
@@ -0,0 +1,16 @@
+/* Вывести сотрудников, которые старше своего менеджера, но были наняты позже своего менеджера. 
+ * Вывести полное имя сотрудника(Фамилия<Пробел>Имя), день рождения, дата найма, полное имя менеджера, день рождения, дата найма.
+ * (employee_full_name, employee_birth_date, employee_hire_date, manager_full_name, manager_birth_date, manager_hire_date)   
+ */
+
+ select concat(e.last_name, ' ', e.first_name) as employee_full_name
+      , e.birth_date as employee_birth_date
+      , e.hire_date  as employee_hire_date
+      , concat(m.last_name, ' ', m.first_name) as manager_full_name
+      , m.birth_date as manager_birth_date
+      , m.hire_date  as manager_hire_date
+   from employee e 
+   join employee m on e.reports_to = m.employee_id 
+  where e.birth_date < m.birth_date -- работник старше своего менеджера 
+    and e.hire_date > m.hire_date  -- работник нанят позже менеджера
+  
\ No newline at end of file
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task4.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task4.sql
new file mode 100644
index 0000000..02dca42
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task4.sql
@@ -0,0 +1,28 @@
+/* Для всех треков жанра Rock и Metal, для каждого артиста подсчитать количество треков. 
+ * Вывести имя артиста, количество треков. (artist_name, qty)  
+ */
+
+   select ar."name" as artist_name
+   		, count(t.track_id) as qty 
+	 from track t
+	 join genre g on t.genre_id = g.genre_id 
+	 join album a on t.album_id = a.album_id 
+	 join artist ar on a.artist_id = ar.artist_id 
+    where g."name" in ('Rock', 'Metal')
+ group by ar.artist_id 
+        , ar."name" 
+ order by count(t.track_id)
+         
+	/*select ar."name" 
+	    	 , g."name" 
+	    	 , t.track_id 
+	    	 , t."name" 
+	    	 , a.album_id 
+	    	 , a.title 
+		 from track t
+		 join genre g on t.genre_id = g.genre_id 
+		 join album a on t.album_id = a.album_id 
+		 join artist ar on a.artist_id = ar.artist_id 
+	    where g."name" in ('Rock', 'Metal')
+	 order by ar."name", t.track_id   
+ */      
\ No newline at end of file
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task5.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task5.sql
new file mode 100644
index 0000000..f2c2b39
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task5.sql
@@ -0,0 +1,42 @@
+/* Для каждого сотрудника 
+ * подсчитать количество клиентов, 
+ * количество выполненных заказов, 
+ * количество уникальных адресов доставки 
+ * общее число приобретенных треков
+ * вывести полное имя сотрудника. 
+ * (employee_full_name, invoices_count, customers_count, addresses_count, tracks_count)
+ */
+
+    select concat(e.last_name, ' ', e.first_name) as employee_full_name
+       	 , count(distinct c.customer_id) as customers_count
+       	 , count(distinct i.invoice_id) as invoices_count
+       	 , count(distinct i.billing_address) as addresses_count
+       	 , count(iline.track_id) as tracks_count
+      from employee e 
+ left join customer c on e.employee_id = c.support_rep_id
+ left join invoice i on i.customer_id = c.customer_id 
+ left join invoice_line iline on i.invoice_id = iline.invoice_id 
+  group by e.employee_id
+         , concat(e.last_name, ' ', e.first_name) 
+    
+         /* 
+  select *
+    from invoice i 
+   left join invoice_line iline on i.invoice_id = iline.invoice_id 
+   
+    select e.employee_id 
+    	 , e.title  
+   		 , concat(e.last_name, ' ', e.first_name) as employee_full_name
+       	 , c.customer_id
+       	 , i.invoice_id
+       	 , i.billing_address 
+       	 , iline.track_id
+      from employee e 
+ left join customer c on e.employee_id = c.support_rep_id
+ left join invoice i on i.customer_id = c.customer_id 
+ left join invoice_line iline on i.invoice_id = iline.invoice_id 
+  order by e.employee_id */
+  
+  
+ 
+ 
\ No newline at end of file
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task6.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task6.sql
new file mode 100644
index 0000000..0b78e7c
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task6.sql
@@ -0,0 +1,51 @@
+/* Выполнить сегментацию клиентов по количеству букв "а" в его фамилии - Группа 'A' - 0 букв, 'B' - 1 буква, 'C' - 2 буквы, 'D' - 3 и более букв.
+ * Для каждой группы вывести количество уникальных типов медиа, купленных клиентами по трекам из различных жанров метала. 
+ * Вывести имя группы и количество уникальных типов медиа (segment_group, cnt)
+ * */
+
+  select case when LENGTH(c.last_name) - LENGTH(REPLACE(lower(c.last_name), 'a', '')) = 0 then 'A' 
+              when LENGTH(c.last_name) - LENGTH(REPLACE(lower(c.last_name), 'a', '')) = 1 then 'B' 
+              when LENGTH(c.last_name) - LENGTH(REPLACE(lower(c.last_name), 'a', '')) = 2 then 'C' 
+              when LENGTH(c.last_name) - LENGTH(REPLACE(lower(c.last_name), 'a', '')) = 3 then 'D' 
+           else 'E' end as segment_group 
+       , count(distinct t.media_type_id) as cnt
+    from customer c
+    join invoice i on c.customer_id = i.customer_id 
+    join invoice_line il on il.invoice_id = i.invoice_id 
+    join track t on il.track_id = t.track_id 
+    join genre g on g.genre_id = t.genre_id 
+   where lower(g."name") like '%metal%'
+group by case when LENGTH(c.last_name) - LENGTH(REPLACE(lower(c.last_name), 'a', '')) = 0 then 'A' 
+              when LENGTH(c.last_name) - LENGTH(REPLACE(lower(c.last_name), 'a', '')) = 1 then 'B' 
+              when LENGTH(c.last_name) - LENGTH(REPLACE(lower(c.last_name), 'a', '')) = 2 then 'C' 
+              when LENGTH(c.last_name) - LENGTH(REPLACE(lower(c.last_name), 'a', '')) = 3 then 'D' 
+           else 'E' end
+
+       /*     
+  select c.last_name
+       , i.invoice_id 
+       , il.invoice_line_id 
+       , il.track_id 
+       , t.media_type_id
+       , g.genre_id 
+    from customer c
+    join invoice i on c.customer_id = i.customer_id 
+    join invoice_line il on il.invoice_id = i.invoice_id 
+    join track t on il.track_id = t.track_id 
+    join genre g on g.genre_id = t.genre_id 
+   where lower(g."name") like '%metal%' 
+  order by c.last_name
+  
+    select t.media_type_id
+    from customer c
+    join invoice i on c.customer_id = i.customer_id 
+    join invoice_line il on il.invoice_id = i.invoice_id 
+    join track t on il.track_id = t.track_id 
+    join genre g on g.genre_id = t.genre_id 
+   where lower(g."name") like '%metal%' 
+  group by t.media_type_id
+  
+  
+  */
+
+        
\ No newline at end of file
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task7.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task7.sql
new file mode 100644
index 0000000..04ca89a
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task7.sql
@@ -0,0 +1,65 @@
+/* Вывести компании, которые приобрели больше всех композиций по каждому из жанров.
+ * При этом указать самую популярную композицию по жанру у данной компании. 
+ * (популярность определяется по количеству покупок) (company_name, track_name)
+ */ 
+
+
+with genre_company_cnt_tracks as (--  выведем все заказы с треками, которые купили компании + жанр трека
+								select t.genre_id  
+									   , c.company 
+									   , count(il.track_id) cnt_tracks
+								  from customer c 
+								  join invoice i on i.customer_id = c.customer_id 
+								  join invoice_line il on il.invoice_id = i.invoice_id 
+								  join track t on t.track_id = il.track_id 
+								 where c.company is not null 
+							  group by c.company, t.genre_id
+							  order by t.genre_id, c.company
+				                 ) , 
+  genre_company as (select a.genre_id, a.company
+					   from genre_company_cnt_tracks a
+					  where (a.genre_id, a.company) in (select a1.genre_id,	a1.company
+					    								  from genre_company_cnt_tracks a1
+					    								 where a1.genre_id = a.genre_id
+					    							  order by a1.cnt_tracks desc, a1.company asc
+					    								 limit 1
+					    								  )
+					),
+	company_track_popularity as ( -- треки компании в рамках жанра
+							    select t.genre_id
+								      , c.company
+								      , t.track_id
+								      , t."name" as track_name
+									  , count(il.invoice_line_id) track_popularity
+								  from customer c 
+							 	  join invoice i on i.customer_id = c.customer_id 
+							      join invoice_line il on il.invoice_id = i.invoice_id 
+							      join track t on t.track_id = il.track_id 
+							      join genre_company gc on t.genre_id = gc.genre_id and c.company = gc.company
+							  group by t.genre_id
+								     , c.company
+								     , t.track_id
+								     , t."name")
+								     
+	 select -- ctp.genre_id,  -- для проверки 
+	 		ctp.company, ctp.track_name as top_track_name
+	   from company_track_popularity ctp
+	  where (ctp.genre_id, ctp.company, ctp.track_name) in (select ctp1.genre_id, ctp1.company, ctp1.track_name
+						    								  from company_track_popularity ctp1
+						    								 where ctp1.genre_id = ctp.genre_id
+						    								   and ctp1.company = ctp.company
+						    							  order by ctp1.track_popularity desc, ctp1.track_name asc
+						    								 limit 1
+						    								  )
+	 order by -- ctp.genre_id, -- для проверки 
+	          ctp.company, ctp.track_name
+	
+        
+	 
+	   	          
+	  
+
+
+
+
+ 
\ No newline at end of file
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task8.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task8.sql
new file mode 100644
index 0000000..49af2f3
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task8.sql
@@ -0,0 +1,50 @@
+/* Вывести треки по каждому жанру, которые входять в самые популярные 25% с точки зрения количества покупок. 
+ * Если у нескольких треков одинаково количество приобретенных композиций, популярность определяется в лексикографическом порядке 
+ * (Например, трек, начинающийся с 'A' будет более популярен, чем трек, начинающийся с 'B'). 
+ * Для каждого трека указать популярность в процентах от общего количества покупок по жанру. 
+ * (track_name, popularity)
+ * 
+ * В рамках каждого жанра надо выбрать популярные
+ */
+
+29.03.2021 - Пока еще разбираюсь
+
+
+больше ссреднего - 50% записей 
+моду исп-ть? 
+sorted aggrefatef functions - 
+rank не через оконные ф-ции 
+
+
+select *
+from information_schema.tables 
+where table_schema = 'public'
+
+-- определить топ 25% с точки зрения кол-ва покупок
+with genre_tracks as (
+						select t.genre_id 
+							 , t.track_id
+							 , t."name"  as track_name
+							 , count(il.invoice_id) as cnt_sales
+						  from track t 
+						  join invoice_line il ON il.track_id = t.track_id 
+						 group by t.genre_id 
+						 		, t.track_id
+						 		, t."name" 
+						 order by t.genre_id, count(il.invoice_id) desc, t."name" 
+						 ) 
+ 
+		 
+ select g.genre_id
+ 	  , g.track_id 
+ 	  , g.track_name
+ 	  , g.cnt_sales
+ 	  , N -- номер в рамках группы
+ 	  , (select trunc(count (1) * 0.25) from genre_tracks g1 where g1.genre_id = g.genre_id) N -- граница топ 25% в группе
+   from genre_tracks g 
+   
+  
+  --- пронумеровать в рамках группы 
+  --- 25% считать от максимальго номера в группе
+					 
+			select trunc()
\ No newline at end of file
diff --git a/Week3/solutions/hw2_dorzhiev_ardan/hw2_task9.sql b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task9.sql
new file mode 100644
index 0000000..579c9a7
--- /dev/null
+++ b/Week3/solutions/hw2_dorzhiev_ardan/hw2_task9.sql
@@ -0,0 +1,42 @@
+/* Для каждого альбома жанр определяется как наибольшая суммарная продолжительность треков по жанру. 
+ * 
+ * Вывести альбом, жанр, и общее количество купленных песен по нему. (album_name, genre_name, cnt)
+ * 
+ * */
+
+with album_agg as (select a.album_id 
+					 , g.genre_id
+					 , sum(t.milliseconds) ms_tracks
+				  from album a 
+				  join track t on t.album_id = a.album_id 
+				  join genre g on t.genre_id = g.genre_id 
+				  -- where a.album_id in (73, 109) -- FOR TEST 
+				  group by a.album_id 
+					 	 , g.genre_id
+				  order by a.album_id 
+		        ) ,
+	album_genre as (select a1.album_id
+						 , a1.genre_id
+					  from album_agg a1
+					  where (a1.album_id, a1.genre_id) = (SELECT a2.album_id, a2.genre_id
+					  		   								FROM album_agg a2
+					  		   							   where a1.album_id = a2.album_id
+					  		   							     and a1.genre_id = a2.genre_id
+					  		   							    order by a2.ms_tracks desc 
+					  		   							    limit 1
+					  		   								)			   
+					  					   
+					  					   
+					  					   
+				   )
+
+ select a2.title as album_name
+ 	  , g."name" as genre_name
+ 	  , count(il.track_id) as cnt
+   from album_genre a  
+   join album a2 on a.album_id = a2.album_id 
+   join genre g on a.genre_id = g.genre_id 
+   join track t on a.album_id = t.album_id 
+   join invoice_line il on t.track_id = il.track_id 
+  group by a2.title 
+  		 , g."name"