SQL Basic Commands ( using mysql )

Database Related Commands :

• To create a database :

CREATE DATABASE   database_name  ; ``` There is a default database already present called sys

• To use your database :

USE  database_name  ;

• To Delete your Database

DROP DATABASE  database name  ;

• To make your database in readonly mode :

ALTER DATABASE  database_name  `READ ONLY = 1`;

Table related commands :

• To create a Table :

CREATE TABLE table_name  ( Column1 INT, Column2 VARCHAR(50), Column3 DECIMAL(5,2), Column4 DATE ) ;

	`INT` - this data type is used for only numbers/integers
	`VARCHAR (MAX DIGITS)` - this data type is used for only alphabetical characters
	`DECIMAL(MAX DIGIT, PRESISION)` - this data type is used only for decimal integers
	`DATE` - this data type is used only for entering date

- #### To Select / Show Table :
	```mySQL
SELECT * FROM  table_name ;

• To Rename a table :

RENAME TABLE old_name TO new_name ;

- #### To delete a table :
```mySQL
DROP TABLE table_name ;

Column Related Commands :

• To add  a column to the table :

ALTER TABLE table_name ADD new_table_name VARCHAR(15) ;

	

- #### To rename a column :
```mySQL
ALTER TABEL table_name  RENAME COLUMN old_column TO new_column ;

• To change a column data type :

ALTER TABLE  table_name  MODIFY COLUMN column_name  VARCHAR(20) ;

• To change the position of a column :

ALTER TABLE  table_name  MODIFY  column_name  VARCHAR(100)  AFTER after_which_column_it_should_come ;

- #### To change position of column to first :
```mySQl
ALTER TABLE  table_name  MODIFY  coulmn_name  VARCHAR(100) FIRST ;

• To delete a column :

ALTER TABLE  table_name DROP COLUMN column_name  ;

Row Related Commands :

• To create a single row :

INSERT INTO table_name VALUES ( 1, “ Name ”, 23.56, “ 2024-12-25 “) ;

	
	For `INT` data type Ex : 1
	
	For `VARCHAR` data type Ex : “ Name “
	
	For `DATE` data type Ex : “ YYYY-MM-DD “

- #### To create multiple rows at same time :
	```mySQL
INSERT INTO table_name VALUES    ( 2, “Name1" , 21.10, “ 2023-11-1“) 
	                             ( 3, “Name2 “, 20.99, “ 2022-12-31“) 
	                             (  ……….etc………….) ;

                                    

• To delete a row :

  DELETE FROM table_name WHERE coulmn_name = 6 ;

Data Commands :

• To show only particular column :

SELECT column_name1, column_name2 FROM table_name

• To search a Particular Data :

SELECT * FROM table_name WHERE column_name = 3 ( given data type is INT ) ;

Also works with  :

WHERE column_name >= 12 ( data type is INT so ) ;

Also works with  :

WHERE column_name != “Name1“ ( Not equal to) ;