-- echo initialization
CREATE TABLE aggregation_func(id int, num int, price float, addr char, birthday date);

INSERT INTO aggregation_func VALUES (1, 18, 10.0, 'abc', '2020-01-01');
INSERT INTO aggregation_func VALUES (2, 15, 20.0, 'abc', '2010-01-11');
INSERT INTO aggregation_func VALUES (3, 12, 30.0, 'def', '2021-01-21');
INSERT INTO aggregation_func VALUES (4, 15, 30.0, 'dei', '2021-01-31');

-- echo 1. count
SELECT count(*) FROM aggregation_func;

SELECT count(num) FROM aggregation_func;

-- echo 2. min
SELECT min(num) FROM aggregation_func;

SELECT min(price) FROM aggregation_func;

SELECT min(addr) FROM aggregation_func;

-- echo 3. max
SELECT max(num) FROM aggregation_func;

SELECT max(price) FROM aggregation_func;

SELECT max(addr) FROM aggregation_func;

-- echo 4. avg
SELECT avg(num) FROM aggregation_func;

SELECT avg(price) FROM aggregation_func;

-- echo 5. error with *
SELECT min(*) FROM aggregation_func;
SELECT max(*) FROM aggregation_func;
SELECT avg(*) FROM aggregation_func;

-- echo 6. error with redundant columns
SELECT count(*,num) FROM aggregation_func;
SELECT min(num,price) FROM aggregation_func;
SELECT max(num,price) FROM aggregation_func;
SELECT avg(num,price) FROM aggregation_func;

-- echo 7. error with empty columns
SELECT count() FROM aggregation_func;
SELECT min() FROM aggregation_func;
SELECT max() FROM aggregation_func;
SELECT avg() FROM aggregation_func;

-- echo 8. error with non-existent columns
SELECT count(id2) FROM aggregation_func;
SELECT min(id2) FROM aggregation_func;
SELECT max(id2) FROM aggregation_func;
SELECT avg(id2) FROM aggregation_func;

-- echo 9. select many aggregation
SELECT min(num),max(num),avg(num) FROM aggregation_func;