new codes

Author: ankurbhambri

30_question/auto_Repair.sql

@@ -0,0 +1,52 @@
+/*
+
+CREATE TABLE auto_repair_data (
+    client VARCHAR(2),
+    auto VARCHAR(2),
+    repair_date INTEGER,
+    indicator VARCHAR(10),
+    value VARCHAR(10)
+);
+
+
+INSERT INTO auto_repair_data (client, auto, repair_date, indicator, value) VALUES
+('c1', 'a1', 2022, 'level', 'good'),
+('c1', 'a1', 2022, 'velocity', '90'),
+('c1', 'a1', 2023, 'level', 'regular'),
+('c1', 'a1', 2023, 'velocity', '80'),
+('c1', 'a1', 2024, 'level', 'wrong'),
+('c1', 'a1', 2024, 'velocity', '70'),
+('c2', 'a1', 2022, 'level', 'good'),
+('c2', 'a1', 2022, 'velocity', '90'),
+('c2', 'a1', 2023, 'level', 'wrong'),
+('c2', 'a1', 2023, 'velocity', '50'),
+('c2', 'a2', 2024, 'level', 'good'),
+('c2', 'a2', 2024, 'velocity', 80);
+
+
+"50"	"wrong"	1
+"70"	"wrong"	1
+"80"	"good"	1
+"80"	"regular"	1
+"90"	"good"	2
+
+*/
+
+
+select
+	velocity,
+	coalesce (good, 0) as good,
+	coalesce (wrong, 0) as wrong,
+	coalesce (regular, 0) as regular
+from crosstab('select 
+					b.value as velocity, a.value as level, count(1) as value
+				from 
+					auto_repair_data a 
+				join 
+					auto_repair_data b on a.client=b.client and a.auto=b.auto and a.repair_date=b.repair_date
+				where 
+					a.indicator=''level'' and b.indicator=''velocity''
+				group by 1,2
+				order by 1,2'
+			, 'select distinct value from auto_repair_data where indicator=''level'' order by value')
+as result(velocity varchar, good bigint, regular bigint, wrong bigint)

30_question/remove_outliers.sql

@@ -0,0 +1,34 @@
+/*
+
+PROBLEM STATEMENT: In the given input table, there are hotel ratings which are either too high or too low compared to the standard ratings the hotel receives each year. Write a query to identify and exclude these outlier records as shown in expected output below.
+Your output should follow the same order of records as shown.
+
+CREATE TABLE hotel_ratings (
+    hotel VARCHAR(50),
+    year INTEGER,
+    rating DECIMAL(2,1)
+);
+
+
+INSERT INTO hotel_ratings (hotel, year, rating) VALUES
+('Radisson Blu', 2020, 4.8),
+('Radisson Blu', 2021, 3.5),
+('Radisson Blu', 2022, 3.2),
+('Radisson Blu', 2023, 3.4),
+('InterContinental', 2020, 4.2),
+('InterContinental', 2021, 4.5),
+('InterContinental', 2022, 1.5),
+('InterContinental', 2023, 3.8);
+
+*/
+
+select *, row_number() over(partition by hotel order by rating) from hotel_ratings
+
+select 
+	hotel, min(rating), max(rating), 
+	percentile_cont(0.1) within group(order by rating) "P10",
+	percentile_cont(0.5) within group(order by rating) "P50",
+	percentile_cont(0.75) within group(order by rating) "P75", 
+	percentile_cont(0.9) within group(order by rating) "P90",
+	percentile_cont(0.99) within group(order by rating) "P99"
+from hotel_ratings group by hotel

Notes.md

@@ -0,0 +1,5 @@
+# By default (range between unbounded preceding and current row):
+- This specifies that the window frame includes all rows from the start of the partition up to and including the current row.
+
+# Explicitly stated (range between unbounded preceding and unbounded following):
+- This specifies that the window frame includes all rows from the start of the partition up to the end of the partition, regardless of the current row.

README.md

@@ -1,2 +1,2 @@
 # SQL-Learn
-PostgreSQL
+PostgreSQL