Necessary MySql command

to log in 
=================
mysql -u root -p

to show databases
===================
SHOW DATABASES;

to select a database
======================
USE databaseName;

RENAME TABLE <old table name> TO <newtable name>

to show tables;
==============================
SHOW TABLES;

to show details of a specific table
===================================
DESCRIBE tableName;

to create a database
============================
CREATE DATABASE databaseName

to delete a database 
======================
DROP DATABASE databaseName

to create a table under a database
===============================
CREATE TABLE tableName(
id INT(11) AUTO_INCREMENT PRIMARY KEY NOT NULL,
name VARCHAR(30) NOT NULL,
email VARCHAR(30) NOT NULL,
contact INT(11),
time TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

to delete a table
======================================
DROP TABLE tableName;

add primary key to existing table
==============================
ALTER TABLE tableName
ADD PRIMARY KEY (columnName);

remove primary key from a table;
===============================
ALTER TABLE tableName
DROP PRIMARY KEY;

How to delete a column in existing table
====================================
ALTER TABLE tableName
DROP COLUMN
columnName;

How to add a new column in existing table;
=========================================
ALTER TABLE tableName
ADD COLUMN
columnName;

How to add a new column with current timestamp;
===================================
ALTER TABLE tableName
ADD COLUMN
time TIMESTAMP DEFAULT CURRENT_TIMESTAMP;

How to change datatype of column in mysql
==================================
ALTER TABLE tableName
MODIFY (COLUMN = optional)
columnName VARCHAR(30);

alter a column to be auto increment;
=================================
ALTER TABLE tableName 
MODIFY COLUMN (column keyword is optional) 
columnName INT AUTO_INCREMENT;

insertion in a table
=============================
INSERT INTO 
tableName (column1, column2, column3) 
VALUES ('value_1', 'value_2', 'value_3');

to show all row in table;
===============================
SELECT * FROM tableName;

to update a row in table;
===================================
UPDATE tableName 
SET country = 'india', name = 'Vasanth', email = 'vasanth@gmail.com'
WHERE id = 2; 

to delete a row in a table
=================================
DELETE FROM tableName WHERE id = 3;

how to move a column OR sort column
==========================================
ALTER TABLE tableName 
MODIFY COLUMN (column keyword is optional)
id INT(11) AFTER another_column_name;


ALTER TABLE tableName
MODIFY COLUMN (column keyword is optional)
id INT(11) FIRST;