JeansBolong/mysql.MD

## mysql.MD

      
    Raw
  

              mysql.MD
            
          
    MySQL

Getting started:

http://www.sqlteaching.com/
https://www.codecademy.com/courses/learn-sql

Related tutorials:

MySQL-CLI
Analyzing Business Metrics
SQL joins infografic

Tools:

DataGrip
Sequel Pro

Commands

Access monitor: mysql -u [username] -p; (will prompt for password)
Show all databases: show databases;
Access database: mysql -u [username] -p [database] (will prompt for password)
Create new database: create database [database];
Select database: use [database];
Determine what database is in use: select database();
Show all tables: show tables;
Show table structure: describe [table];
List all indexes on a table: show index from [table];
Create new table with columns: CREATE TABLE [table] ([column] VARCHAR(120), [another-column] DATETIME);
Adding a column: ALTER TABLE [table] ADD COLUMN [column] VARCHAR(120);
Adding a column with an unique, auto-incrementing ID: ALTER TABLE [table] ADD COLUMN [column] int NOT NULL AUTO_INCREMENT PRIMARY KEY;
Inserting a record: INSERT INTO [table] ([column], [column]) VALUES ('[value]', [value]');
MySQL function for datetime input: NOW()
Selecting records: SELECT * FROM [table];
Explain records: EXPLAIN SELECT * FROM [table];
Selecting parts of records: SELECT [column], [another-column] FROM [table];
Counting records: SELECT COUNT([column]) FROM [table];
Counting and selecting grouped records: SELECT *, (SELECT COUNT([column]) FROM [table]) AS count FROM [table] GROUP BY [column];
Selecting specific records: SELECT * FROM [table] WHERE [column] = [value]; (Selectors: <, >, !=; combine multiple selectors with AND, OR)
Select records containing [value]: SELECT * FROM [table] WHERE [column] LIKE '%[value]%';
Select records starting with [value]: SELECT * FROM [table] WHERE [column] LIKE '[value]%';
Select records starting with val and ending with ue: SELECT * FROM [table] WHERE [column] LIKE '[val_ue]';
Select a range: SELECT * FROM [table] WHERE [column] BETWEEN [value1] and [value2];
Select with custom order and only limit: SELECT * FROM [table] WHERE [column] ORDER BY [column] ASC LIMIT [value]; (Order: DESC, ASC)
Updating records: UPDATE [table] SET [column] = '[updated-value]' WHERE [column] = [value];
Deleting records: DELETE FROM [table] WHERE [column] = [value];
Delete all records from a table (without dropping the table itself): DELETE FROM [table];
(This also resets the incrementing counter for auto generated columns like an id column.)
Delete all records in a table: truncate table [table];
Removing table columns: ALTER TABLE [table] DROP COLUMN [column];
Deleting tables: DROP TABLE [table];
Deleting databases: DROP DATABASE [database];
Custom column output names: SELECT [column] AS [custom-column] FROM [table];
Export a database dump (more info here): mysqldump -u [username] -p [database] > db_backup.sql
Use --lock-tables=false option for locked tables (more info here).
Import a database dump (more info here): mysql -u [username] -p -h localhost [database] < db_backup.sql
Logout: exit;
Aggregate functions

Select but without duplicates: SELECT distinct name, email, acception FROM owners WHERE acception = 1 AND date >= 2015-01-01 00:00:00
Calculate total number of records: SELECT SUM([column]) FROM [table];
Count total number of [column] and group by [category-column]: SELECT [category-column], SUM([column]) FROM [table] GROUP BY [category-column];
Get largest value in [column]: SELECT MAX([column]) FROM [table];
Get smallest value: SELECT MIN([column]) FROM [table];
Get average value: SELECT AVG([column]) FROM [table];
Get rounded average value and group by [category-column]: SELECT [category-column], ROUND(AVG([column]), 2) FROM [table] GROUP BY [category-column];
Multiple tables

Select from multiple tables: SELECT [table1].[column], [table1].[another-column], [table2].[column] FROM [table1], [table2];
Combine rows from different tables: SELECT * FROM [table1] INNER JOIN [table2] ON [table1].[column] = [table2].[column];
Combine rows from different tables but do not require the join condition: SELECT * FROM [table1] LEFT OUTER JOIN [table2] ON [table1].[column] = [table2].[column]; (The left table is the first table that appears in the statement.)
Rename column or table using an alias: SELECT [table1].[column] AS '[value]', [table2].[column] AS '[value]' FROM [table1], [table2];
Users functions

List all users: SELECT User,Host FROM mysql.user;
Create new user: CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
Grant ALL access to user for * tables: GRANT ALL ON database.* TO 'user'@'localhost';
Find out the IP Address of the Mysql Host

SHOW VARIABLES WHERE Variable_name = 'hostname'; (source)
Export csv from mysql query

SELECT id, column1, column2 FROM table INTO OUTFILE '/tmp/mysqlfiles/table.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n';
(source)

  
## otherMySql.md

      
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              otherMySql.md
            
          
    MySQL Cheat Sheet


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;