ДЗ к 4 уроку

HomeWork_Lesson-4.sql

@@ -0,0 +1,132 @@
+USE vk;
+
+SHOW TABLES;
+
+DESC users;
+
+SELECT * FROM users LIMIT 10;
+
+ALTER TABLE users MODIFY COLUMN phone VARCHAR(13) NOT NULL UNIQUE;
+
+SELECT RAND();
+
+SELECT RAND() * 999;
+
+SELECT 100 + RAND() * 999; 
+
+SELECT FLOOR(100 + RAND() * 899);
+
+UPDATE users SET phone  = CONCAT(phone, FLOOR(100 + RAND() * 899));
+
+DESC profiles;
+
+SELECT * FROM profiles LIMIT 10;
+
+
+CREATE TEMPORARY TABLE genders (gender CHAR(1));
+
+INSERT INTO genders VALUES ('m'), ('f');
+
+SELECT * FROM genders;
+
+UPDATE profiles SET gender = (
+	SELECT gender FROM genders ORDER BY RAND() LIMIT 1
+	);
+
+UPDATE profiles SET updated_at = NOW() WHERE created_at > updated_at;
+
+SHOW TABLES;
+
+DESC messages;
+
+SELECT * FROM messages m LIMIT 10;
+
+UPDATE messages SET
+	from_user_id = FLOOR(1 + RAND() * 100),
+	to_user_id = FLOOR(1 + RAND() * 100);
+
+SELECT COUNT(*) FROM users;
+SELECT * FROM users;
+
+DESC media;
+
+SELECT * FROM media LIMIT 10;
+
+SELECT * FROM media_types;
+
+DELETE FROM media_types;
+
+INSERT INTO media_types (name) VALUES
+	('photo'),
+	('video'),
+	('audio');
+
+TRUNCATE media_types;
+
+UPDATE media SET
+	media_type_id = FLOOR(1 + RAND() * 3);
+
+SELECT * FROM media LIMIT 10;
+
+UPDATE media SET
+	user_id = FLOOR(1 + RAND() * 100);
+
+UPDATE media SET file_path =
+	CONCAT ('http:// dropbox/vk/file_', FLOOR(1 + RAND() * 9999));
+
+UPDATE media SET size = FLOOR(99999 + RAND() * 9999999)
+	WHERE size < 10000;
+
+UPDATE media SET metadata = CONCAT ('{"owner":"',
+	(SELECT CONCAT(first_name, '', last_name) FROM users WHERE id = user_id),
+	'"}');
+
+DESC media;
+
+ALTER TABLE media MODIFY COLUMN metadata JSON;
+
+SELECT id, JSON_EXTRACT(metadata, '$.owner') AS owner
+	FROM media
+	WHERE id = 1;
+
+UPDATE media SET metadata =
+	JSON_REPLACE(metadata, '$.owner', 'REPLACE VALUE')
+WHERE id = 1;
+
+SELECT * FROM media WHERE id = 1;
+
+SHOW TABLES;
+
+SELECT * FROM friendship LIMIT 10;
+
+UPDATE friendship SET
+	user_id = FLOOR(1 + RAND() * 100),
+	friend_id = FLOOR(1 + RAND() * 100);
+
+DESC friendship;
+
+SELECT * FROM friendship_statuses;
+
+TRUNCATE friendship_statuses;
+
+INSERT INTO friendship_statuses (name) VALUES
+	('Requested'),
+	('Confirmed'),
+	('Rejected');
+
+UPDATE friendship SET
+	status_id = FLOOR(1 + RAND() * 3);
+
+DESC communities;
+
+SELECT * FROM communities;
+
+DELETE FROM communities WHERE id > 20;
+
+DESC communities_users;
+
+SELECT * FROM communities_users LIMIT 50;
+
+UPDATE communities_users SET
+	community_id = FLOOR(1 + RAND() * 20),
+	user_id = FLOOR(1 + RAND() * 100);