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ariella_bondi_el
May 03, 2019
In Databases
Help with SQL commands to interact with a MySQL database. MySQL Locations Mac /usr/local/mysql/bin Windows /Program Files/MySQL/MySQL version/bin Xampp /xampp/mysql/bin Add mysql to your PATH # Current Session export PATH=${PATH}:/usr/local/mysql/bin # Permanantly echo 'export PATH="/usr/local/mysql/bin:$PATH"' >> ~/.bash_profile On Windows - https://www.qualitestgroup.com/resources/knowledge-center/how-to-guide/add-mysql-path-windows/ Login mysql -u root -p Show Users SELECT User, Host FROM mysql.user; Create User CREATE USER 'someuser'@'localhost' IDENTIFIED BY 'somepassword'; Grant All Priveleges On All Databases GRANT ALL PRIVILEGES ON * . * TO 'someuser'@'localhost'; FLUSH PRIVILEGES; Show Grants SHOW GRANTS FOR 'someuser'@'localhost'; Remove Grants REVOKE ALL PRIVILEGES, GRANT OPTION FROM 'someuser'@'localhost'; Delete User DROP USER 'someuser'@'localhost'; Exit exit; Show Databases SHOW DATABASES Create Database CREATE DATABASE acme; Delete Database DROP DATABASE acme; Select Database USE acme; Create Table CREATE TABLE users( id INT AUTO_INCREMENT, first_name VARCHAR(100), last_name VARCHAR(100), email VARCHAR(50), password VARCHAR(20), location VARCHAR(100), dept VARCHAR(100), is_admin TINYINT(1), register_date DATETIME, PRIMARY KEY(id) ); Delete / Drop Table DROP TABLE tablename; Show Tables SHOW TABLES; Insert Row / Record INSERT INTO users (first_name, last_name, email, password, location, dept, is_admin, register_date) values ('Brad', 'Traversy', 'brad@gmail.com', '123456','Massachusetts', 'development', 1, now()); Insert Multiple Rows INSERT INTO users (first_name, last_name, email, password, location, dept, is_admin, register_date) values ('Fred', 'Smith', 'fred@gmail.com', '123456', 'New York', 'design', 0, now()), ('Sara', 'Watson', 'sara@gmail.com', '123456', 'New York', 'design', 0, now()),('Will', 'Jackson', 'will@yahoo.com', '123456', 'Rhode Island', 'development', 1, now()),('Paula', 'Johnson', 'paula@yahoo.com', '123456', 'Massachusetts', 'sales', 0, now()),('Tom', 'Spears', 'tom@yahoo.com', '123456', 'Massachusetts', 'sales', 0, now()); Select SELECT * FROM users; SELECT first_name, last_name FROM users; Where Clause SELECT * FROM users WHERE location='Massachusetts'; SELECT * FROM users WHERE location='Massachusetts' AND dept='sales'; SELECT * FROM users WHERE is_admin = 1; SELECT * FROM users WHERE is_admin > 0; Delete Row DELETE FROM users WHERE id = 6; Update Row UPDATE users SET email = 'freddy@gmail.com' WHERE id = 2; Add New Column ALTER TABLE users ADD age VARCHAR(3); Modify Column ALTER TABLE users MODIFY COLUMN age INT(3); Order By (Sort) SELECT * FROM users ORDER BY last_name ASC; SELECT * FROM users ORDER BY last_name DESC; Concatenate Columns SELECT CONCAT(first_name, ' ', last_name) AS 'Name', dept FROM users; Select Distinct Rows SELECT DISTINCT location FROM users; Between (Select Range) SELECT * FROM users WHERE age BETWEEN 20 AND 25; Like (Searching) SELECT * FROM users WHERE dept LIKE 'd%'; SELECT * FROM users WHERE dept LIKE 'dev%'; SELECT * FROM users WHERE dept LIKE '%t'; SELECT * FROM users WHERE dept LIKE '%e%'; Not Like SELECT * FROM users WHERE dept NOT LIKE 'd%'; IN SELECT * FROM users WHERE dept IN ('design', 'sales'); Create & Remove Index CREATE INDEX LIndex On users(location); DROP INDEX LIndex ON users; New Table With Foreign Key (Posts) CREATE TABLE posts( id INT AUTO_INCREMENT, user_id INT, title VARCHAR(100), body TEXT, publish_date DATETIME DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY(id), FOREIGN KEY (user_id) REFERENCES users(id) ); Add Data to Posts Table INSERT INTO posts(user_id, title, body) VALUES (1, 'Post One', 'This is post one'),(3, 'Post Two', 'This is post two'),(1, 'Post Three', 'This is post three'),(2, 'Post Four', 'This is post four'),(5, 'Post Five', 'This is post five'),(4, 'Post Six', 'This is post six'),(2, 'Post Seven', 'This is post seven'),(1, 'Post Eight', 'This is post eight'),(3, 'Post Nine', 'This is post none'),(4, 'Post Ten', 'This is post ten'); INNER JOIN SELECT users.first_name, users.last_name, posts.title, posts.publish_date FROM users INNER JOIN posts ON users.id = posts.user_id ORDER BY posts.title; New Table With 2 Foriegn Keys CREATE TABLE comments( id INT AUTO_INCREMENT, post_id INT, user_id INT, body TEXT, publish_date DATETIME DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY(id), FOREIGN KEY(user_id) references users(id), FOREIGN KEY(post_id) references posts(id) ); Add Data to Comments Table INSERT INTO comments(post_id, user_id, body) VALUES (1, 3, 'This is comment one'),(2, 1, 'This is comment two'),(5, 3, 'This is comment three'),(2, 4, 'This is comment four'),(1, 2, 'This is comment five'),(3, 1, 'This is comment six'),(3, 2, 'This is comment six'),(5, 4, 'This is comment seven'),(2, 3, 'This is comment seven'); Left Join SELECT comments.body, posts.title FROM comments LEFT JOIN posts ON posts.id = comments.post_id ORDER BY posts.title; Join Multiple Tables SELECT comments.body, posts.title, users.first_name, users.last_name FROM comments INNER JOIN posts on posts.id = comments.post_id INNER JOIN users on users.id = comments.user_id ORDER BY posts.title; Aggregate Functions SELECT COUNT(id) FROM users; SELECT MAX(age) FROM users; SELECT MIN(age) FROM users; SELECT SUM(age) FROM users; SELECT UCASE(first_name), LCASE(last_name) FROM users; Group By SELECT age, COUNT(age) FROM users GROUP BY age; SELECT age, COUNT(age) FROM users WHERE age > 20 GROUP BY age; SELECT age, COUNT(age) FROM users GROUP BY age HAVING count(age) >=2;
MySQL Cheat Sheet content media
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ariella_bondi_el
May 03, 2019
In OS
In this post, I will show you how to free extra disk space used by docker, sometimes you download and test a docker images that take some disk space this includes images, containers, volumes and network, these objects are not removed by default once you are done with them which ends up taking some space on your disk unless you are telling docker these objects will always be there. Requirements Docker Engine on your local PC. Basic Docker Knowledge. When you build images frequently on the same image there is tendency of creating dangling images, which is just copies of some things of previous built images and these are the ones that take a lot space of your hard disk, there is a docker command that free extra disk space used by docker and this will help you also free some space when you build large image that fails at the middle of building process. docker system prune The command above will warn you as shown below. When you accept to continue you will see what docker system prune will do for you as shown below As you can see above the command delete some containers and networks that were taking some space on your disk Conclusion: You must use this command time to time to remove all the images, containers, networks or volumes that you won’t be using any more Credit for Izweb technologies
How to free extra disk space used by Docker content media
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