目錄
概覽
SQL Commands
DDL
- DDL(Data definition language): it is used to define data structures
CREATE
CREATE TABLE employees_2 (
emp_no INT NOT NULL,
birth_date DATE NOT NULL,
first_name VARCHAR(14) NOT NULL,
last_name VARCHAR(16) NOT NULL,
gender ENUM ('M','F') NOT NULL,
hire_date DATE NOT NULL,
PRIMARY KEY (emp_no)
);
DESC employees_2;
ALTER
ALTER TABLE employees_2 ADD a TINYINT NOT NULL;
ALTER TABLE employees_2 MODIFY a INT NOT NULL;
ALTER TABLE employees_2 DROP a;
TRUNCATE
TRUNCATE TABLE employees_2;
DROP
DROP TABLE employees_2;
DML
- DML(Data Manipulation Language): it is used to manipulate data itself
INSERT
INSERT INTO employees VALUES (500000,'1958-05-01','Test','Tsukuda','M','1997-11-30');
SELECT
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 500000 | 1958-05-01 | Test | Tsukuda | M | 1997-11-30 |
+--------+------------+------------+-----------+--------+------------+
UPDATE
UPDATE employees SET last_name = 'Test' WHERE first_name = 'Test'
DELETE
DELETE FROM employees WHERE first_name = 'Test'
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 499999 | 1958-05-01 | Sachin | Tsukuda | M | 1997-11-30 |
+--------+------------+------------+-----------+--------+------------+
DCL
- DCL(Data Control Language): it is used to control access to data stored in a database (Authorization)
GRANT
GRANT SELECT ON employees.* TO guest@localhost IDENTIFIED BY '123456';
mycli -uguest -p123456
USE employees;
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 499999 | 1958-05-01 | Sachin | Tsukuda | M | 1997-11-30 |
+--------+------------+------------+-----------+--------+------------+
INSERT INTO employees VALUES (500000,'1958-05-01','Test','Tsukuda','M','1997-11-30');
(1142, "INSERT command denied to user 'guest'@'localhost' for table 'employees'")
mycli -uroot -p123456
GRANT INSERT ON employees.* TO guest@localhost IDENTIFIED BY '123456';
mycli -uguest -p123456
USE employees;
INSERT INTO employees VALUES (500000,'1958-05-01','Test','Tsukuda','M','1997-11-30');
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 500000 | 1958-05-01 | Test | Tsukuda | M | 1997-11-30 |
+--------+------------+------------+-----------+--------+------------+
REVOKE
mycli -uroot -p123456
REVOKE INSERT ON employees.* FROM guest@localhost;
mycli -uguest -p123456
USE employees;
INSERT INTO employees VALUES (500000,'1958-05-01','Test','Tsukuda','M','1997-11-30');
(1142, "INSERT command denied to user 'guest'@'localhost' for table 'employees'")
TCL
- TCL(Transaction Control Language): it is used to manage transactions in the database
COMMIT
START TRANSACTION;
UPDATE employees SET last_name = 'Test' WHERE first_name = 'Test'
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 500000 | 1958-05-01 | Test | Test | M | 1997-11-30 |
+--------+------------+------------+-----------+--------+------------+
UPDATE employees SET gender = 'F' WHERE first_name = 'Test'
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 500000 | 1958-05-01 | Test | Test | F | 1997-11-30 |
+--------+------------+------------+-----------+--------+------------+
COMMIT
ROLLBACK
ROLLBACK
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 500000 | 1958-05-01 | Test | Test | F | 1997-11-30 |
+--------+------------+------------+-----------+--------+------------+
START TRANSACTION;
UPDATE employees SET hire_date = '2000-01-01' WHERE first_name = 'Test';
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 500000 | 1958-05-01 | Test | Test | F | 2000-01-01 |
+--------+------------+------------+-----------+--------+------------+
ROLLBACK
SELECT * FROM employees ORDER BY emp_no desc LIMIT 1;
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date |
+--------+------------+------------+-----------+--------+------------+
| 500000 | 1958-05-01 | Test | Test | F | 1997-11-30 |
+--------+------------+------------+-----------+--------+------------+
