sql 
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*

SELECT Name FROM 
WHERE Population > 120000 AND Country == "IR";

SELECT DISTINCT CITY FROM STATION WHERE LEFT(CITY,1) IN ('A','E','I','O','U');

SELECT DISTINCT CITY FROM STATION WHERE UPPER(CITY) RLIKE '^[AEIOU]';

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%";

SELECT DISTINCT CITY FROM STATION WHERE UPPER(SUBSTR(CITY, 1, 1)) IN ('A', 'E', 'I', 'O', 'U');

SELECT Continent, FLOOR(AVG(CITY.Population)) AS AveragePopulation
FROM CITY
JOIN COUNTRY ON CITY.CountryCode = COUNTRY.Code
GROUP BY Continent;

WITH RECURSIVE CTE AS (
    SELECT 20 N
    UNION ALL
    SELECT N - 1 FROM CTE WHERE N > 0
)
SELECT REPEAT('* ', N) FROM CTE

sql 

BEGIN;
INSERT INTO employees (first_name, last_name, start_date, salary, job_title, manager_id, department_id) VALUES ('Elizabeth', 'Christensen', current_date, 1, 'Master of the Highwire', 2, 2) RETURNING employee_id;
COMMIT;

SELECT    * FROM employees  WHERE    first_name = 'Elizabeth' AND    last_name = 'Christensen';

BEGIN;

INSERT INTO employees (first_name, last_name, start_date, salary, job_title, manager_id, department_id) VALUES ('Chris', 'Winslett', current_date, 1, 'Jr Director of the Highwire', 2, 2) RETURNING employee_id;

ROLLBACK;

SELECT * FROM employees WHERE first_name = 'Chris' AND last_name = 'Winslett';

BEGIN;
INSERT INTO employees (first_name, last_name) VALUES ('Tom', 'Jones') RETURNING employee_id;
COMMIT;

BEGIN; 
INSERT INTO employees (first_name, last_name, start_date, salary, job_title, manager_id, department_id) VALUES ('Chris', 'Winslett', current_date, 1, 'Jr Director of the Highwire', 2, 2);   
INSERT INTO dependents (first_name, last_name, employee_id)  VALUES ('oldest', 'kid', (SELECT employee_id FROM employees WHERE first_name = 'Chris' AND last_name = 'Winslett'));   
INSERT INTO dependents (first_name, last_name, employee_id) VALUES ('youngest', 'kid', (SELECT employee_id FROM employees WHERE first_name = 'Chris' AND last_name = 'Winslett')); 
COMMIT;

BEGIN;   
INSERT INTO employees (first_name, last_name, start_date, salary, job_title, manager_id, department_id) VALUES ('Bob', 'Young', current_date, 1, 'Jr Director of the Highwire', 2, 2);   
INSERT INTO dependents (first_name, last_name, employee_id) VALUES ('oldest', 'kid', (SELECT employee_id FROM employees WHERE first_name = 'Bob' AND last_name = 'Young'));   
INSERT INTO dependents (first_name, last_name, employee_id) VALUES (null, 'kid', (SELECT employee_id FROM employees WHERE first_name = 'Bob' AND last_name = 'Young')); 
COMMIT;

SELECT *  FROM employees  WHERE  first_name = 'Bob' AND last_name = 'Young';