Tuesday, 6 March 2018

MySQL Command Line Cheatsheet

SHOW databases;
CREATE DATABASE ppdbmankoraya;
USE ppdbmankoraya;
SHOW tables;
CREATE TABLE `haldepan` (
  `id` int(5) NOT NULL,
  `konten` text NOT NULL
CREATE TABLE `dashboard` (
  `id` int(11) NOT NULL,
  `konten` text NOT NULL

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 ANDOR)
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 ueSELECT * 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: DESCASC)
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 aliasSELECT [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';

Other ref: https://www.geeksforgeeks.org/sql-tutorial/


The following code block is an example, which creates a CUSTOMERS table with an ID as a primary key and NOT NULL are the constraints showing that these fields cannot be NULL while creating records in this table −
   ID   INT              NOT NULL,
   AGE  INT              NOT NULL,
   ADDRESS  CHAR (25) ,
   SALARY   DECIMAL (18, 2),       
You can verify if your table has been created successfully by looking at the message displayed by the SQL server, otherwise you can use the DESCcommand as follows −
| Field   | Type          | Null | Key | Default | Extra |
| ID      | int(11)       | NO   | PRI |         |       |
| NAME    | varchar(20)   | NO   |     |         |       |
| AGE     | int(11)       | NO   |     |         |       |
| ADDRESS | char(25)      | YES  |     | NULL    |       |
| SALARY  | decimal(18,2) | YES  |     | NULL    |       |
5 rows in set (0.00 sec)
Now, you have CUSTOMERS table available in your database which you can use to store the required information related to customers.

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