Shakil-RU / MySQL_Notes_For_Beginner

A comprehensive repository providing beginner-friendly documentation and guidance for learning MySQL database management.

MySQL Basic Documentation Notes

Name: Abdullah Numan Shakil
Dept of Computer Science And Engineering
University of Rajshahi.
This repository contains basic documentation notes for MySQL, a popular open-source relational database management system.

Purpose

The purpose of this repository is to provide a comprehensive guide to MySQL for beginners. It covers the basic concepts and operations involved in using MySQL, including installation, database creation, table creation, data insertion, querying, updating, and deletion. Whether you are new to MySQL or need a refresher, this documentation will help you understand and navigate the fundamentals of working with MySQL.

Table of Contents

1. Introduction to MySQL
2. Installation guide for MySQL
3. Connecting to MySQL
4. Creating a database in MySQL
5. Dropping a database in MySQL
6. Creating tables in MySQL
7. Altering tables in MySQL
8. Dropping tables in MySQL
9. Inserting data into MySQL tables
10. Querying data from MySQL tables
11. Updating data in MySQL tables
12. Deleting data from MySQL tables

For more practice follow the following Notes

Use sample database like employees database in mysql.

Data Manipulation

1. SELECT:

Explanation: SELECT is used to retrieve data from one or more columns of one or more tables in a database.

Syntax:

SELECT
    *
FROM
    table_name;

Example:

SELECT
    *
FROM
    departments;

Results:

dept_no	dept_name
d009	Customer Service
d005	Development
d002	Finance
d003	Human Resources
d001	Marketing
d004	Production
d006	Quality Management
d008	Research
d007	Sales

2. SELECT DISTINCT:

Explanation: SELECT DISTINCT is used to retrieve unique values from a column in the result set.

Syntax:

SELECT DISTINCT
    column_name
FROM
    table_name;

Example:

SELECT DISTINCT
    title
FROM
    titles;

Result:

title
Senior Engineer
Staff
Engineer
Senior Staff
Assistant Engineer
Technique Leader
Manager

3. LIMIT:

Explanation: LIMIT is used to limit the number of rows returned in a result set.

Syntax:

SELECT
    *
FROM
    table_name
LIMIT number_of_limit;

Example:

SELECT
    *
FROM
    employees
LIMIT 10;

Result:

emp_no	birth_date	first_name	last_name	gender	hire_date
10001	1953-09-02	Georgi	Facello	M	1986-06-26
10002	1964-06-02	Bezalel	Simmel	F	1985-11-21
10003	1959-12-03	Parto	Bamford	M	1986-08-28
10004	1954-05-01	Chirstian	Koblick	M	1986-12-01
10005	1955-01-21	Kyoichi	Maliniak	M	1989-09-12
10006	1953-04-20	Anneke	Preusig	F	1989-06-02
10007	1957-05-23	Tzvetan	Zielinski	F	1989-02-10
10008	1958-02-19	Saniya	Kalloufi	M	1994-09-15
10009	1952-04-19	Sumant	Peac	F	1985-02-18
10010	1963-06-01	Duangkaew	Piveteau	F	1989-08-24

4. ORDER BY:

Explanation: ORDER BY is used to sort the result set in ascending or descending order based on one or more columns.

Syntax:

SELECT
    column_name
FROM
    table_name
ORDER BY
    column_name
DESC;

Example:

SELECT
    salary
FROM
    salaries
ORDER BY
    salary
DESC;

Result:

salary
158220
157821
156286
155709
155513
155377
155190
154888

5. GROUP BY:

Explanation: GROUP BY is used to group rows based on one or more columns, usually used with aggregate functions like SUM, COUNT, etc.

Syntax:

SELECT
    column_name,
    COUNT(*) AS total_column
FROM
    table_name
GROUP BY
    column_name;

Example:

SELECT
    title,
    COUNT(*) AS total_title
FROM
    titles
GROUP BY
    title;

Result:

title	total_title
Assistant Engineer	15128
Engineer	115003
Manager	24
Senior Engineer	97750
Senior Staff	92853
Staff	107391
Technique Leader	15159

6. HAVING:

Explanation: HAVING is used to filter groups based on specified conditions in a GROUP BY query.

Syntax:

SELECT
    column_name,
    COUNT(*) AS total_column
FROM
    table_name
GROUP BY
    column_name
HAVING
    COUNT(*) < number_of_column;

Example:

SELECT
    title,
    COUNT(*) AS total_titles
FROM
    titles
GROUP BY
    title
HAVING
    COUNT(*) < 20000;

Result:

title	total_titles
Assistant Engineer	15128
Manager	24
Technique Leader	15159

7. ROLLUP:

Explanation: ROLLUP is used to generate subtotals and grand totals in a GROUP BY query.

Syntax:

SELECT
    column_name1,
    column_name2,
    COUNT(*) AS total_column
FROM
    table_name
GROUP BY
    column_name1,
    column_name2 WITH ROLLUP
LIMIT number_of_limit;

Example:

SELECT
    birth_date,
    gender,
    COUNT(*) AS total_employee
FROM
    employees
GROUP BY
    birth_date,
    gender WITH ROLLUP
LIMIT 25;

Result:

birth_date	gender	total_employee
1952-02-01	M	6
1952-02-01	NULL	6
1952-02-02	M	48
1952-02-02	F	22
1952-02-02	NULL	70
1952-02-03	M	40
1952-02-03	F	23
1952-02-03	NULL	63
1952-02-04	M	42
1952-02-04	F	28
1952-02-04	NULL	70
1952-02-05	M	35
1952-02-05	F	23
1952-02-05	NULL	58
1952-02-06	M	44
1952-02-06	F	28
1952-02-06	NULL	72
1952-02-07	M	33
1952-02-07	F	23
1952-02-07	NULL	56
1952-02-08	M	32
1952-02-08	F	29
1952-02-08	NULL	61
1952-02-09	M	45
1952-02-09	F	33

8. WHERE:

Explanation: WHERE is used to filter rows based on specified conditions.

Syntax:

SELECT
    column_name1
FROM
    table_name
WHERE
    column_name2 = specific_value;

Example:

SELECT
    emp_no
FROM
    employees
WHERE
    hire_date = '2000-01-01';

Result:

emp_no
108201

9. AND:

Explanation: AND is used to combine multiple conditions in a WHERE clause.

Syntax:

SELECT
    column_name1
FROM
    table_name
WHERE
    column_name2 = specific_value AND column_name3 = another_specific_value;

Example:

SELECT
    emp_no
FROM
    employees
WHERE
    hire_date = '1990-01-01' AND gender = 'M';

Result:

emp_no
18199
21865
24751
28869
39204
44808
49447
50654

10. OR:

Explanation: OR is used to combine multiple conditions in a WHERE clause, where at least one condition must be true.

Syntax:

SELECT
    column_name1,
    column_name2,
    column_name3
FROM
    table_name
WHERE
    column_name2 = specific_value OR column_name3 = another_specific_value;

Example:

SELECT
    emp_no,
    birth_date,
    hire_date
FROM
    employees
WHERE
    birth_date = '1990-01-01' OR hire_date = '1990-01-01';

Result:

emp_no	birth_date	hire_date
18199	1953-02-25	1990-01-01
18873	1961-03-05	1990-01-01
21865	1964-10-24	1990-01-01
24751	1953-01-24	1990-01-01
28869	1961-01-08	1990-01-01
33268	1958-08-27	1990-01-01
34515	1964-04-12	1990-01-01
39204	1956-03-08	1990-01-01
44480	1952-06-13	1990-01-01

11. IN:

Explanation: IN is used to specify multiple possible values for a column in a WHERE clause.

Syntax:

SELECT
    column_name1,
    column_name2
FROM
    table_name
WHERE
    column_name2 IN (specific_value, another_specific_value, ...);

Example:

SELECT
    emp_no,
    dept_no
FROM
    dept_manager
WHERE
    dept_no IN('d001', 'd002');

Result:

emp_no	dept_no
110022	d001
110039	d001
110085	d002
110114	d002

12. BETWEEN:

Explanation: BETWEEN is used to select values within a range in a WHERE clause.

Syntax:

SELECT
    column_name1,
    column_name2
FROM
    table_name
WHERE
    column_name2 BETWEEN start_value AND end_value;

Example:

SELECT
    emp_no,
    hire_date
FROM
    employees
WHERE
    hire_date BETWEEN '1985-01-01' AND '1990-01-01';

Result:

emp_no	hire_date
10001	1986-06-26
10002	1985-11-21
10003	1986-08-28
10004	1986-12-01
10005	1989-09-12
10006	1989-06-02
10007	1989-02-10
10009	1985-02-18
10010	1989-08-24
10013	1985-10-20

13. LIKE:

Explanation: LIKE is used to search for a specified pattern in a column in a WHERE clause.

Syntax:

SELECT
    column_name1,
    column_name2
FROM
    table_name
WHERE
    column_name2 LIKE 'starting_with%';

Example:

SELECT
    emp_no,
    first_name
FROM
    employees
WHERE
    first_name LIKE 'Jo%';

Result:

emp_no	first_name
10194	Josyula
10439	Jolita
10471	Jouko
10556	JoAnna
10660	Jouko
10751	Jordanka
11004	JoAnna
11017	Jovan
11097	Jovan
11201	Jouko
11282	Josyula
11286	Joydip
11387	Jordanka
11391	Jouko
11421	Josyula
11638	JoAnne
11697	JoAnne
12047	Jordanka
12196	JoAnne
12418	Jongsuk
12486	Joydip
12494	JoAnna
12599	Jouni
12673	Jouni
12911	Jordanka

14. IS NULL:

Explanation: IS NULL is used to check if a column value is NULL in a WHERE clause.

Syntax:

SELECT
    column_name1
FROM
    table_name
WHERE
    column_name2 IS NULL;

Example:

SELECT
    emp_no
FROM
    salaries
WHERE
    salary IS NULL;

Result:

emp_no
10001
10002
10003

15. Table & Column Aliases:

Explanation: Aliases are used to provide a temporary name for a table or column in a query.

Syntax:

SELECT
    t.column_name1 AS name1
FROM
    table_name t
WHERE
    t.column_name2 = specific_value;

Example:

SELECT
    a.emp_no AS employee_number
FROM
    employees a
WHERE
    a.gender = 'M';

Result:

employee_number
10001
10003
10004
10005
10008
10012
10013
10014
10015
10016

16. Joins:

Explanation: Joins are used to combine rows from two or more tables based on related columns.

Syntax:

SELECT
    t.column_name1 AS employee_number,
    u.column_name2 AS employee_position
FROM
    table_name1 t
JOIN table_name2 u ON
    t.column_name1 = u.column_name1
WHERE
    t.column_name2 = specific_value;

Example:

SELECT
    a.emp_no AS employee_number,
    b.title AS employee_position
FROM
    employees a
JOIN titles b ON
    a.emp_no = b.emp_no
WHERE
    a.gender = 'M';

Result:

employee_number	employee_position
10001	Senior Engineer
10003	Senior Engineer
10004	Engineer
10004	Senior Engineer
10005	Senior Staff
10005	Staff
10008	Assistant Engineer
10012	Engineer
10012	Senior Engineer
10013	Senior Staff
10014	Engineer

17. INNER JOIN:

Explanation: INNER JOIN returns rows that have matching values in both tables involved in the join.

Syntax:

SELECT
    t.column_name1,
    u.column_name1
FROM
    table_name1 t
INNER JOIN table_name2 u ON
    t.column_name1 = u.column_name1;

Example:

SELECT
    a.dept_no,
    b.dept_name
FROM
    dept_emp a
INNER JOIN departments b ON
    a.dept_no = b.dept_no;

Result:

dept_no	dept_name
d009	Customer Service
d009	Customer Service
d009	Customer Service
d009	Customer Service
d009	Customer Service
d009	Customer Service
d009	Customer Service
d009	Customer Service

18. LEFT JOIN:

Explanation: LEFT JOIN returns all rows from the left table and the matched rows from the right table. If no match is found, NULL values are returned.

Syntax:

SELECT
    t.column_name1,
    u.column_name2
FROM
    table_name1 t
LEFT JOIN table_name2 u ON
    t.column_name1 = u.column_name1;

Example:

SELECT
    a.emp_no,
    b.hire_date
FROM
    dept_manager a
LEFT JOIN employees b ON
    a.emp_no = b.emp_no;

Result:

emp_no	hire_date
110022	1985-01-01
110039	1986-04-12
110085	1985-01-01
110114	1985-01-14
110183	1985-01-01
110228	1985-08-04
110303	1985-01-01
110344	1985-11-22
110386	1988-10-14

19. RIGHT JOIN:

Explanation: RIGHT JOIN returns all rows from the right table and the matched rows from the left table. If no match is found, NULL values are returned.

Syntax:

SELECT
    t.column_name1,
    u.column_name1
FROM
    table_name1 t
RIGHT JOIN table_name2 u ON
    a.column_name1 = b.column_name1;

Example:

SELECT
    a.emp_no,
    b.dept_no
FROM
    employees a
RIGHT JOIN dept_emp b ON
    a.emp_no = b.emp_no;

Result:

emp_no	dept_no
10001	d005
10002	d007
10003	d004
10004	d004
10005	d003
10006	d005
10007	d008
10008	d005
10009	d006
10010	d004

20. Self Join:

Explanation: Self Join is used to join a table with itself, treating it as two separate tables.

Syntax:

SELECT
    t.column_name1,
    t.column_name2,
    u.column_name3,
    ...
FROM
    table_name1 t
JOIN table_name2 u ON
    t.column_name2 = u.column_name3;

Example:

SELECT
    a.dept_no,
    a.from_date,
    b.emp_no,
    b.dept_no,
    b.to_date
FROM
    dept_emp a
JOIN dept_emp b ON
    a.from_date = b.to_date;

Result:

dept_no	from_date	emp_no	dept_no	to_date
d005	2000-07-31	10008	d005	2000-07-31
d005	2000-07-31	10008	d005	2000-07-31
d006	2000-06-26	10010	d004	2000-06-26
d009	2000-06-26	10010	d004	2000-06-26
d004	1996-11-09	10011	d009	1996-11-09
d004	1996-11-09	10011	d009	1996-11-09
d007	1996-11-09	10011	d009	1996-11-09
d005	1996-11-09	10011	d009	1996-11-09
d005	1996-11-09	10011	d009	1996-11-09
d001	1993-08-22	10015	d008	1993-08-22

21. CROSS JOIN:

Explanation: CROSS JOIN returns the Cartesian product of the two tables involved in the join, resulting in all possible combinations of rows.

Syntax:

SELECT
    t.column_name1
    u.column_name2,
    ...
FROM
    table_name1 t
CROSS JOIN table_name2 u;

Example:

SELECT
    a.dept_name,
    b.title
FROM
    departments a
CROSS JOIN titles b;

Result:

dept_name	title
Customer Service	Senior Engineer
Development	Senior Engineer
Finance	Senior Engineer
Human Resources	Senior Engineer
Marketing	Senior Engineer
Production	Senior Engineer
Quality Management	Senior Engineer
Research	Senior Engineer
Sales	Senior Engineer
Customer Service	Staff

22. Derived Tables:

Explanation: Derived Tables are temporary tables created within a query, used to simplify complex queries or calculations.

Syntax:

SELECT
    dt.column_name1,
    dt.name
FROM
    (
    SELECT
        column_name1,
        COUNT(column_name2) AS name
    FROM
        table_name
    GROUP BY
        column_name1
) AS dt;

Example:

SELECT
    dt.emp_no,
    dt.salary_appraisal
FROM
    (
    SELECT
        emp_no,
        COUNT(salary) AS salary_appraisal
    FROM
        salaries
    GROUP BY
        emp_no
) AS dt;

Result:

emp_no	salary_appraisal
10001	17
10002	6
10003	7
10004	16
10005	13
10006	12
10007	14
10008	3
10009	18

23. EXISTS:

Explanation: EXISTS is used to check if a subquery returns any rows, and returns true if at least one row exists.

Syntax:

SELECT
    column_name1
FROM
    table_name1
WHERE
    EXISTS(
    SELECT
        *
    FROM
        table_name2
    WHERE
        table_name1.column_name2 = table_name2.column_name1
);

Example:

SELECT
    first_name
FROM
    employees
WHERE
    EXISTS(
    SELECT
        *
    FROM
        dept_manager
    WHERE
        employees.emp_no = dept_manager.dept_no
);

Result:

first_name

24. UNION:

Explanation: UNION is used to combine result sets of two or more SELECT statements into a single result set.

Syntax:

SELECT
    table_name1.column_name1
FROM
    table_name1
UNION
SELECT
    table_name2.column_name1
FROM
    table_name2;

Example:

SELECT
    departments.dept_name
FROM
    departments
UNION
SELECT
    titles.title
FROM
    titles;

Result:

dept_name
Customer Service
Development
Finance
Human Resources
Marketing
Production
Quality Management

25. INSERT:

Explanation: INSERT is used to insert new rows into a table.

Syntax:

INSERT INTO table_name1(column_name1, column_name2, ...)
VALUES(specific_value1, specific_value2, ...);

Example:

INSERT INTO departments(dept_no, dept_name)
VALUES('d010', 'Software Developement');

Result:

1 row inserted. (Query took 0.0320 seconds.)

26. Insert Multiple Rows:

Explanation: Insert Multiple Rows is used to insert multiple rows into a table in a single INSERT statement.

Syntax:

INSERT INTO table_name1(column_name1, column_name2, ...)
VALUES(specific_value1, specific_value2, ...),(specific_value1, specific_value2, ...);

Example:

INSERT INTO departments(dept_no, dept_name)
VALUES('d010', 'Software Developement'),('d011', 'Software Testing');

Result:

2 rows inserted. (Query took 0.0350 seconds.)

27. INSERT INTO SELECT:

Explanation: INSERT INTO SELECT is used to insert rows into a table by selecting data from another table.

Syntax:

INSERT INTO table_name1(column_name1, column_name2, ...)
SELECT
    column_name1,
    column_name2,
    ...
FROM
    table_name1
GROUP BY
    column_name1
LIMIT number_of_limit;

Example:

INSERT INTO salary_appraisal(emp_no, appraisal)
SELECT
    emp_no,
    COUNT(salary)
FROM
    salaries
GROUP BY
    emp_no
LIMIT 3;

Result:

3 rows inserted. (Query took 0.1550 seconds.)

28. Insert On Duplicate Key Update:

Explanation: Insert On Duplicate Key Update is used to insert new rows into a table, and if a duplicate key is found, update the existing row.

Syntax:

INSERT INTO table_name1(column_name1, column_name2, ...)
VALUES(specific_value1, specific_value2, ...)
ON DUPLICATE KEY
UPDATE
    column_name1 = VALUES(column_name1), 
    column_name2 = VALUES(column_name2);

Example:

INSERT INTO salary_appraisal(emp_no, appraisal)
VALUES('100010', '10')
ON DUPLICATE KEY
UPDATE
    emp_no = VALUES(emp_no), 
	appraisal = VALUES(appraisal);

Result:

1 row inserted. (Query took 0.0660 seconds.)

29. INSERT IGNORE:

Explanation: INSERT IGNORE is used to insert new rows into a table, ignoring any duplicate key errors.

Syntax:

INSERT IGNORE
INTO table_name1(column_name1, column_name2, ...)
VALUES(specific_value1, specific_value2, ...);

Example:

INSERT IGNORE
INTO salary_appraisal(emp_no, appraisal)
VALUES('100010', '10');

Result:

1 row inserted. (Query took 0.0880 seconds.)

30. UPDATE:

Explanation: UPDATE is used to modify existing rows in a table.

Syntax:

UPDATE
    table_name1
SET
    column_name1 = specific_value1
WHERE
    column_name2 = specific_value2;

Example:

UPDATE
    salary_appraisal
SET
    appraisal = '8'
WHERE
    emp_no = '10003';

Result:

1 row affected. (Query took 0.0600 seconds.)

31. UPDATE JOIN:

Explanation: UPDATE JOIN is used to update rows in a table based on a join with another table.

Syntax:

UPDATE
    table_name1 t
JOIN table_name2 u ON
    t.column_name1 = u.column_name2
SET
    t.column_name2 = u.column_name3;

Example:

UPDATE
    salary_appraisal a
JOIN dept_emp b ON
    a.emp_no = b.emp_no
SET
    a.dept_no = b.dept_no;

Result:

5 rows affected. (Query took 0.0660 seconds.)

32. DELETE:

Explanation: DELETE is used to delete existing rows from a table.

Syntax:

DELETE
FROM
    table_name1
WHERE
    column_name1 = specific_value1;

Example:

DELETE
FROM
    salary_appraisal
WHERE
    emp_no = '100010';

Result:

2 rows affected. (Query took 0.0910 seconds.)

33. DELETE JOIN:

Explanation: DELETE JOIN is used to delete rows from a table based on a join with another table.

Syntax:

DELETE
    table_name1
FROM
    table_name1
JOIN table_name2 ON table_name1.column_name1 = table_name2.column_name2;

Example:

DELETE
    salary_appraisal
FROM
    salary_appraisal
JOIN employees ON salary_appraisal.emp_no = employees.emp_no;

Result:

3 rows affected. (Query took 0.0950 seconds.)

34. REPLACE:

Explanation: REPLACE is used to insert new rows into a table, and if a duplicate key is found, delete the existing row and insert the new row.

Syntax:

REPLACE
INTO table_name1(column_name1, column_name2, ...)
VALUES(specific_value1, specific_value2, ...);

Example:

REPLACE
INTO salary_appraisal(emp_no, appraisal, dept_no)
VALUES('10005', '14', 'd003');

Result:

1 row affected. (Query took 0.0410 seconds.)

Managing Database:

1. Select a Database:

Explanation: SELECT DATABASE is used to select a specific database to work with.

Syntax:

USE database_name

Syntax:

USE test

2. Create Databases:

Explanation: CREATE DATABASE is used to create a new database.

Syntax:

CREATE DATABASE database_name;

Example:

CREATE DATABASE test;

3. Drop Databases:

Explanation: DROP DATABASE is used to delete an existing database.

Example:

DROP DATABASE database_name;

Example:

DROP DATABASE test;

Managing Tables:

1. MySQL Storage Engines:

Explanation: MySQL supports multiple storage engines for managing tables.

Example:

SHOW ENGINES

Result:

Engine	Support	Comment	Transactions	XA	Savepoints
CSV	YES	Stores tables as CSV files	NO	NO	NO
MRG_MyISAM	YES	Collection of identical MyISAM tables	NO	NO	NO
MEMORY	YES	Hash based, stored in memory, useful for temporary...	NO	NO	NO
Aria	YES	Crash-safe tables with MyISAM heritage. Used for i...	NO	NO	NO
MyISAM	YES	Non-transactional engine with good performance and...	NO	NO	NO
SEQUENCE	YES	Generated tables filled with sequential values	YES	NO	YES
InnoDB	DEFAULT	Supports transactions, row-level locking, foreign ...	YES	YES	YES
PERFORMANCE_SCHEMA	YES	Performance Schema	NO	NO	NO

2. Create Tables:

Explanation: CREATE TABLE is used to create a new table in a database.

Syntax:

CREATE TABLE table_name (
    column1 datatype,
    column2 datatype,
    ...
);

3. AUTO_INCREMENT:

Explanation: AUTO_INCREMENT is used to automatically generate unique values for a column.

Syntax:

CREATE TABLE table_name (
    id INT AUTO_INCREMENT PRIMARY KEY,
    column1 datatype,
    column2 datatype,
    ...
);

4. Rename Tables:

Explanation: RENAME TABLE is used to rename an existing table.

Syntax:

RENAME TABLE old_table_name TO new_table_name;

Example:

RENAME TABLE users TO employees;

5. Alter Tables:

Explanation: ALTER TABLE is used to modify an existing table's structure.

Syntax:

ALTER TABLE table_name
    ADD column_name datatype,
    MODIFY column_name datatype,
    DROP column_name;

6. Drop Columns:

Explanation: ALTER TABLE with DROP COLUMN is used to remove a column from an existing table.

Syntax:

ALTER TABLE table_name DROP COLUMN column_name;

Example:

ALTER TABLE employees DROP COLUMN experience;

7. Add Columns:

Explanation: ALTER TABLE with ADD COLUMN is used to add a new column to an existing table.

Syntax:

ALTER TABLE table_name ADD COLUMN column_name datatype;

Example:

ALTER TABLE employees ADD COLUMN experience INT;

8. Drop Tables:

Explanation: DROP TABLE is used to delete an existing table from the database.

Syntax:

DROP TABLE table_name;

Example:

DROP TABLE employees;

9. Temporary Tables:

Explanation: Temporary tables are created and used for storing temporary data.

Syntax:

CREATE TEMPORARY TABLE temp_table_name (
    column1 datatype,
    column2 datatype,
    ...
);

10. Truncate Tables:

Explanation: TRUNCATE TABLE is used to delete all rows from an existing table.

Syntax:

TRUNCATE TABLE table_name;

Example:

TRUNCATE TABLE employees;

11. Generated Columns:

Explanation: Generated columns are computed columns whose values are automatically calculated.

Syntax:

CREATE TABLE table_name (
    column1 datatype,
    column2 datatype,
    generated_column_name datatype AS (expression) VIRTUAL,
    ...
);

Mysql Constraints:

1. Primary Key:

Explanation: Primary key is used to uniquely identify each record in a table.

Syntax:

CREATE TABLE table_name (
    id INT PRIMARY KEY,
    column1 datatype,
    column2 datatype,
    ...
);

2. Foreign Key:

Explanation: Foreign key is used to establish a relationship between two tables based on a column.

Syntax:

CREATE TABLE table_name1 (
    id INT PRIMARY KEY,
    column1 datatype,
    column2 datatype,
    ...
);

CREATE TABLE table_name2 (
    id INT,
    column3 datatype,
    column4 datatype,
    FOREIGN KEY (id) REFERENCES table_name1(id)
);

3. Disable Foreign Key Checks:

Explanation: FOREIGN_KEY_CHECKS system variable is used to enable or disable foreign key checks.

Example:

SET FOREIGN_KEY_CHECKS = 0;
-- Perform actions that would violate foreign key constraints
SET FOREIGN_KEY_CHECKS = 1;

4. UNIQUE Constraint:

Explanation: UNIQUE constraint ensures that values in a column or a group of columns are unique.

Syntax:

CREATE TABLE table_name (
    id INT,
    column1 datatype,
    column2 datatype,
    UNIQUE (id)
);

5. NOT NULL Constraint:

Explanation: NOT NULL constraint ensures that a column cannot have NULL values.

Syntax:

CREATE TABLE table_name (
    id INT,
    column1 datatype NOT NULL,
    column2 datatype,
    ...
);

6. DEFAULT Constraint:

Explanation: DEFAULT constraint sets a default value for a column if no value is provided.

Syntax:

CREATE TABLE table_name (
    id INT,
    column1 datatype DEFAULT default_value,
    column2 datatype,
    ...
);

7. CHECK Constraint:

Explanation: CHECK constraint is used to enforce a condition on the values in a column.

Syntax:

CREATE TABLE table_name (
    id INT,
    column1 datatype,
    column2 datatype,
    column3 datatype CHECK (column3 > 0),
    ...
);

Mysql Datatypes

1. BIT:

Explanation: BIT data type is used to store bit-field values.

Syntax:

column_name BIT(n);

2. BOOLEAN:

Explanation: BOOLEAN data type is used to store true/false values.

Syntax:

column_name BOOLEAN;

3. CHAR:

Explanation: CHAR data type is used to store fixed-length character strings.

Syntax:

column_name CHAR(n);

4. DATE:

Explanation: DATE data type is used to store a date value.

Syntax:

column_name DATE;

5. DATETIME:

Explanation: DATETIME data type is used to store a date and time value.

Syntax:

column_name DATETIME;

6. DECIMAL:

Explanation: DECIMAL data type is used to store exact numeric values with a specified precision and scale.

Syntax:

column_name DECIMAL(precision, scale);

7. ENUM:

Explanation: ENUM data type is used to store one value from a predefined list of values.

Syntax:

column_name ENUM('value1', 'value2', ...);

8. INT:

Explanation: INT data type is used to store whole numbers.

Syntax:

column_name INT;

9. JSON:

Explanation: JSON data type is used to store JSON (JavaScript Object Notation) documents.

Syntax:

column_name JSON;

10. TIME:

Explanation: TIME data type is used to store a time value.

Syntax:

column_name TIME;

11. TIMESTAMP:

Explanation: TIMESTAMP data type is used to store a timestamp value.

Syntax:

column_name TIMESTAMP;

12. VARCHAR:

Explanation: VARCHAR data type is used to store variable-length character strings.

Syntax:

column_name VARCHAR(n);

Mysql Globalization:

1. MySQL Character Set:

Explanation: MySQL character set is used to define the encoding for storing textual data.

Syntax:

ALTER TABLE table_name CONVERT TO CHARACTER SET charset_name;

2. MySQL Collation:

Explanation: MySQL collation is used to define the comparison rules for string data based on a specific character set.

Syntax:

ALTER TABLE table_name CONVERT TO CHARACTER SET charset_name COLLATE collation_name;

Advanced Mysql Concepts

1. Stored Procedures:

Explanation: Stored procedures are pre-written SQL statements that are stored in the database and can be executed later.

Syntax:

CREATE PROCEDURE procedure_name()
BEGIN
    -- SQL statements here
END;

2. Triggers:

Explanation: Triggers are database objects that automatically execute in response to specific events, such as insert, update, or delete operations on a table.

Syntax:

CREATE TRIGGER trigger_name
AFTER INSERT ON table_name
FOR EACH ROW
BEGIN
    -- SQL statements here
END;

3. Views:

Explanation: Views are virtual tables that are derived from the result of a query and can be used like regular tables.

Syntax:

CREATE VIEW view_name AS
SELECT column1, column2
FROM table_name
WHERE condition;

4. Indexes:

Explanation: Indexes are data structures that improve the speed of data retrieval operations on database tables.

Syntax:

CREATE INDEX index_name
ON table_name (column1, column2);

5. Administration:

Explanation: Administration refers to the tasks involved in managing and maintaining a MySQL database, such as user management, backup and restore, and performance tuning.

• User Management:

Syntax:

CREATE USER username@hostname IDENTIFIED BY 'password';

• Backup:

Syntax:

mysqldump -u username -p database_name > backup.sql

• Restore:

Syntax:

mysql -u username -p database_name < backup.sql

• Performance Tuning: Analyzing query performance, optimizing database schema, etc.