MYSQL

SELECT * FROM students WHERE first_name='Bob' and postcode=2303;

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

SELECT COUNT(CITY) - COUNT(DISTINCT CITY)

(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)

SELECT DISTINCT(CITY)
FROM STATION 
WHERE LEFT(CITY, 1) IN ('a', 'e', 'i', 'o', 'u')

SELECT DISTINCT (CITY)
FROM STATION
WHERE RIGHT (CITY,1) IN ('a', 'e', 'i', 'o', 'u')

SELECT DISTINCT(CITY)
FROM STATION 
WHERE LEFT(CITY,1) IN ('a', 'e', 'i', 'o', 'u')
AND
RIGHT (CITY,1) IN ('a', 'e', 'i', 'o', 'u')

SELECT DISTINCT(CITY)
FROM STATION 
WHERE NOT LEFT(CITY, 1) IN ('a', 'e', 'i', 'o', 'u')

SELECT DISTINCT(CITY)
FROM STATION 
WHERE NOT RIGHT (CITY, 1) IN ('a', 'e', 'i', 'o', 'u')
AND
NOT LEFT (CITY, 1) IN ('a', 'e', 'i', 'o', 'u')

SELECT Name FROM STUDENTS 
WHERE Marks > 75
ORDER BY RIGHT (NAME,3) ASC, ID ASC

SELECT name FROM Employee
WHERE salary > 2000
AND months < 10
ORDER BY employee_id ASC

SELECT ROUND (MIN(LAT_N), 4)
FROM STATION
WHERE LAT_N > 38.7780

SELECT ROUND (LONG_W, 4) FROM STATION 
WHERE LAT_N = (SELECT MIN (LAT_N) FROM STATION WHERE LAT_N > 38.7780)

SELECT COUNT(NAME)
FROM CITY
WHERE POPULATION > 100000;

select  country.continent, FLOOR(AVG(city.population)) from country
join city on city.countrycode = country.code
group by country.continent

SELECT CEIL((AVG(salary)) - (AVG(REPLACE(salary, '0', '')))) FROM employees

DECLARE @rows int-- Declare                   
SELECT @rows = 1 -- initialization                  
WHILE @rows <= 20 -- Condition                 
BEGIN --Begin                           
PRINT replicate('* ', @rows)--Print      
SET @rows = @rows + 1 --Set             
END --End

DECLARE @rows int                  -- Declare 
SELECT @rows = 20                  -- initialization 
WHILE @rows > 0                  -- Condition
BEGIN                             -- Begin
PRINT replicate('* ', @rows)       -- Print
SET @rows = @rows - 1               -- Set
END                               -- end
               

SELECT (Salary*Months)as earnings, COUNT(*) 
FROM EMPLOYEE
GROUP BY 1
ORDER By earnings DESC limit 1

SELECT Students.name
From Students 
JOIN Friends on Students.ID = Friends.ID
JOIN Packages on Friends.ID = Packages.ID
JOIN Packages p2 on Friends.Friend_ID = p2.ID
Where Packages.Salary < p2.Salary
ORDER By p2.Salary

SELECT C.company_code,
         C.founder,
         Count(DISTINCT E.lead_manager_code),
         Count(DISTINCT E.senior_manager_code),
         Count(DISTINCT E.manager_code),
         Count(DISTINCT E.employee_code)
FROM Company C
JOIN Employee E
WHERE C.company_code = E.company_code
GROUP BY  C.company_code, C.founder
ORDER BY  C.company_code