SQL 기본 2

 

 

SELECT COUNT(*) FROM users;

 

SELECT COUNT(country) FROM users;

 

SELECT COUNT(DISTINCT country) FROM users;

 

SELECT ROUNT(AVG(pirce),2) AS avgprice FROM products;

 

SELECT MIN(price) FROM products;

 

SELECT SUBSTR(created_at, 1, 10) AS day,

               SUBSTR(created_at, 1, 7) AS month

                FROM users;

 

SELECT LENGTH(username), username FROM users;

 

SELECT MIN(LENGTH(username)), username FROM users;

 

SELECT SUM(price) FROM products;

 

SELECT ROUND(AVG (id), 2) FROM products WHERE id <= 30;

 

SELECT COUNT(DISTINCT id) FROM userss WHERE LENGTH(username) <= 17;

 

SELECT COUNT(DISTINCT id) AS UniqCnt FROM users GROUP BY country;

 

SELECT COUNT(DISTINCT id) AS uniqusercnt FROM users

              WHERE country = 'korea' AND is_marketing_agreee = 1 ;

 

SELECT country, COUNT(DISTINCT id) AS uniqusercnt

              FROM users WHERE is_marketing_agree = 1

              GROUP BY country;

 

SELECT * FROM users u INNERT JOIN orders o ON u.id = o.user_id;