SQL Basic solution document

Question 1:
Query all columns for all American cities in the CITY table with populations larger than 100000. The CountryCode for America is USA.
The CITY table is described as follows:

Solution:
select * from CITY
where POPULATION >100000
and COUNTRYCODE = 'USA';


Question 2:
Query the NAME field for all American cities in the CITY table with populations larger than 120000. The CountryCode for America is USA.
The CITY table is described as follows:

Solution:
select NAME from CITY
where COUNTRYCODE = 'USA' AND POPULATION > 120000;


Question 3:  SELECT ALL
Query all columns (attributes) for every row in the CITY table.
The CITY table is described as follows:

Solution:
select * from CITY;


Question 4: Select by ID
Query all columns for a city in CITY with the ID 1661.
The CITY table is described as follows:

Solution:
SELECT * FROM CITY WHERE ID=1661;


Question 5:  Japanese Cities’ Attribute
Query all attributes of every Japanese city in the CITY table. The COUNTRYCODE for Japan is JPN.
The CITY table is described as follows:

Solution:
select * from CITY where COUNTRYCODE = 'JPN';


Question 6:  Japanese Cities’ Names
Query the names of all the Japanese cities in the CITY table. The COUNTRYCODE for Japan is JPN.
The CITY table is described as follows:

Solution:
SELECT NAME FROM CITY WHERE COUNTRYCODE ='JPN';


Question 7: Weather Observation Station 1
Query a list of CITY and STATE from the STATION table.
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

Solution:
SELECT CITY, STATE FROM STATION;


Question 8: Weather Observation Station 3
Query a list of CITY names from STATION for cities that have an even ID number. Print the results in any order, but exclude duplicates from the answer.
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

Solution:
SELECT DISTINCT(CITY) FROM STATION WHERE ID%2=0;


Question 9: Weather Observation Station 4
Find the difference between the total number of CITY entries in the table and the number of distinct CITY entries in the table.
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.
For example, if there are three records in the table with CITY values 'New York', 'New York', 'Bengalaru', there are 2 different city names: 'New York' and 'Bengalaru'. The query returns 1, because 
Total number of records-number of unique city names = 3-2 =1

Solution:
SELECT  COUNT(CITY)-COUNT(DISTINCT(CITY)) FROM STATION;


Question 10: Weather Observation Station 5

Query the two cities in STATION with the shortest and longest CITY names, as well as their respective lengths (i.e.: number of characters in the name). If there is more than one smallest or largest city, choose the one that comes first when ordered alphabetically.
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.
Sample Input
For example, CITY has four entries: DEF, ABC, PQRS and WXY.
Sample Output
ABC 3
PQRS 4
Explanation
When ordered alphabetically, the CITY names are listed as ABC, DEF, PQRS, and WXY, with lengths 3,3,4 and 3. The longest name is PQRS, but there are  options for shortest named city. Choose ABC, because it comes first alphabetically.
Note
You can write two separate queries to get the desired output. It need not be a single query.

Solution:
(select city, length(city) from station order by length(city) asc, city asc limit 1)
union
(select city, length(city) from station order by length(city) desc, city asc limit 1);


Question 11: Weather Observation Station 6
Query the list of CITY names starting with vowels (i.e., a, e, i, o, or u) from STATION. Your result cannot contain duplicates.
Input Format
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

Solution:
select distinct(CITY) from STATION where CITY LIKE 'a%' OR CITY LIKE 'e%' OR CITY LIKE 'i%' OR CITY LIKE 'o%' OR CITY LIKE 'u%';


Question 12: Weather Observation Station 7
Query the list of CITY names ending with vowels (a, e, i, o, u) from STATION. Your result cannot contain duplicates.
Input Format
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

Solution:
select distinct(CITY) from STATION where CITY LIKE '%a' OR CITY LIKE '%e' OR CITY LIKE '%i' OR CITY LIKE '%o' OR CITY LIKE '%u';


Question 13: Weather Observation Station 8
Query the list of CITY names from STATION which have vowels (i.e., a, e, i, o, and u) as both their first and last characters. Your result cannot contain duplicates.
Input Format
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

Solution:
select distinct(CITY) from STATION 
where (CITY LIKE 'a%' OR CITY LIKE 'e%' OR CITY LIKE 'i%' OR CITY LIKE 'o%' OR CITY LIKE 'u%')
AND
(CITY LIKE '%a' OR CITY LIKE '%e' OR CITY LIKE '%i' OR CITY LIKE '%o' OR CITY LIKE '%u');


Question 14: Weather Observation Station 9
Query the list of CITY names from STATION that do not start with vowels. Your result cannot contain duplicates.
Input Format
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

Solution:
select distinct(CITY) from STATION where CITY NOT in(select CITY where CITY LIKE 'a%' OR CITY LIKE 'e%' OR CITY LIKE 'i%' OR CITY LIKE 'o%' OR CITY LIKE 'u%');


Question 15: Weather Observation Station 10
Query the list of CITY names from STATION that do not end with vowels. Your result cannot contain duplicates.
Input Format
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.
Solution:
select distinct(CITY) from STATION where CITY NOT in(select CITY from STATION where CITY LIKE '%a' OR CITY LIKE '%e' OR CITY LIKE '%i' OR CITY LIKE '%o' OR CITY LIKE '%u');


Question 16: Weather Observation Station 11
Query the list of CITY names from STATION that either do not start with vowels or do not end with vowels. Your result cannot contain duplicates.
Input Format
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

Solution:
SELECT DISTINCT (CITY) FROM STATION
WHERE CITY NOT in(select CITY where CITY LIKE 'a%' OR CITY LIKE 'e%' OR CITY LIKE 'i%' OR CITY LIKE 'o%' OR CITY LIKE 'u%')
OR
CITY NOT in(select CITY from STATION where CITY LIKE '%a' OR CITY LIKE '%e' OR CITY LIKE '%i' OR CITY LIKE '%o' OR CITY LIKE '%u');


Question 17: Weather Observation Station 12
Query the list of CITY names from STATION that do not start with vowels and do not end with vowels. Your result cannot contain duplicates.
Input Format
The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

Solution:
SELECT DISTINCT (CITY) FROM STATION
WHERE CITY NOT in(select CITY where CITY LIKE 'a%' OR CITY LIKE 'e%' OR CITY LIKE 'i%' OR CITY LIKE 'o%' OR CITY LIKE 'u%')
AND
CITY NOT in(select CITY from STATION where CITY LIKE '%a' OR CITY LIKE '%e' OR CITY LIKE '%i' OR CITY LIKE '%o' OR CITY LIKE '%u');


Question 18: Higher Than 75 Marks
Query the Name of any student in STUDENTS who scored higher than 75 Marks. Order your output by the last three characters of each name. If two or more students both have names ending in the same last three characters (i.e.: Bobby, Robby, etc.), secondary sort them by ascending ID.
Input Format
The STUDENTS table is described as follows:  The Name column only contains uppercase (A-Z) and lowercase (a-z) letters.
Sample Input

Sample Output
Ashley
Julia
Belvet
Explanation
Only Ashley, Julia, and Belvet have Marks > 75. If you look at the last three characters of each of their names, there are no duplicates and 'ley' < 'lia' < 'vet'.

Solution:
SELECT Name FROM STUDENTS
WHERE Marks >75
ORDER BY SUBSTR(Name, length(Name)-2, 3), ID;


Question 19: Employee Names
Write a query that prints a list of employee names (i.e.: the name attribute) from the Employee table in alphabetical order.
Input Format
The Employee table containing employee data for a company is described as follows:

where employee_id is an employee's ID number, name is their name, months is the total number of months they've been working for the company, and salary is their monthly salary.
Sample Input

Sample Output
Angela
Bonnie
Frank
Joe
Kimberly
Lisa
Michael
Patrick
Rose
Todd

Solution:
SELECT name FROM Employee
ORDER BY Name asc;

Question 20: Employee Salaries
Write a query that prints a list of employee names (i.e.: the name attribute) for employees in Employee having a salary greater than $2000 per month who have been employees for less than 10 months. Sort your result by ascending employee_id.
Input Format
The Employee table containing employee data for a company is described as follows:
Column	Type
employee_id	INTEGER
name	STRING
months	INTEGER
salary	INTEGER
where employee_id is an employee's ID number, name is their name, months is the total number of months they've been working for the company, and salary is the their monthly salary.
Sample Input
employee_id	name	marks	salary
12228	Rose	15	1968
33645	Angela	1	3443
45692	Frank	17	1608
56118	Patrick	7	1345
59725	Lisa	11	2330
74197	Kimberly	16	4372
78454	Bonnie	8	1771
83565	Michael	6	2017
98607	Todd	5	3396
99989	Joe	9	3573
Sample Output
Angela Michael Todd Joe
Explanation
Angela has been an employee for 1 month and earns $3443 per month. Michael has been an employee for 6 months and earns $2017 per month. Todd has been an employee for 5 months and earns $3396 per month. Joe has been an employee for 9 months and earns $3573 per month. We order our output by ascending employee_id.

Solution:
SELECT name FROM Employee
WHERE salary > 2000
AND months < 10
ORDER BY employee_id asc;