SQL Basic - 알아야 할 사항! (기초)

SQL 구문의 주요 구성 요소:

데이터 정의 언어(DDL)

CREATE object_type object_name;

CREATE TABLE object_name(column_name data_type);

CREATE TABLE sales(purchase_no INT);

-- Add a column in a table
ALTER TABLE sales
ADD COLUMN date_of_purchase DATA;

-- delete an entire table   
DROP TABLE customer;

-- Rename a table   
RENAME TABLE sales TO customer;

데이터 조작 언어(DML)

-- deliver all the records in the table.
    SELECT* FROM sales; 
-- Select specific specific data from the database. 
SELECT row FROM sales;      

-- Choose specific cell to insert values
INSERT INTO sales (purchase_number, date_of_purchase) 
VALUES(1, “12-09-2020”);

-- Insert value
INSERT INTO sales VALUES(1, “12-09-2020”);

UPDATE sales
SET date_of_purchase = “16-11_2020”
WHERE purchase_number =1;

DELETE FROM sales
WHERE purchase_number =1;

데이터 제어 언어(DCL)

GRANT type_of_permission ON database_name.table_name TO ‘username’@‘localhost’

-- Creates user `ochwada` whose password is "password"
CREATE USER ‘ochwada’@‘localhost’ IDENTIFIED BY ‘password’;

-- Allow the user to use all SELECT Statements on the table 'customer' from the 'sales' database.
GRANT SELECT ON sales.customers To ‘ochwada’@‘localhost’;

-- Use all statements and all tables in the 'sales' database.
GRANT ALL ON sales.* To ‘ochwada’@‘localhost’;

REVOKE type_of_permission ON database_name.table_name TO ‘username’@‘localhost’

-- Only the use of SELECT statement will be REVOKED for the table customers in the sales database.  
REVOKE SELECT ON sales.customers To ‘ochwada’@‘localhost’;

-- use of all statements in the 'sales' database will be revoked.   
REVOKE ALL ON sales.* To ‘ochwada’@‘localhost’;

TCL(트랜잭션 제어 언어)

UPDATE sales
SET date_of_purchase = “16-11_2020”
WHERE purchase_number =1;

COMMIT;

UPDATE sales
SET date_of_purchase = “16-11_2020”
WHERE purchase_number =1;
COMMIT;

ROLLBACK;