 CREATE TABLE book(
    book_id INT PRIMARY KEY AUTO_INCREMENT,
    title VARCHAR(50),
    author VARCHAR(30),
    price DECIMAL(8, 2),
    amount INT
);

INSERT INTO book(title, author, price, amount) VALUES ('Мастер и Маргарита', 'Булгаков М.А.', 670.99, 3);
INSERT INTO book(title, author, price, amount) VALUES ('Белая гвардия', 'Булгаков М.А.', 540.50, 5);
INSERT INTO book(title, author, price, amount) VALUES ('Идиот', 'Достоевский Ф.М.', 460.00, 10);
INSERT INTO book(title, author, price, amount) VALUES ('Братья Карамазовы', 'Достоевский Ф.М.', 799.01, 2);

/* При анализе продаж книг выяснилось, что наибольшей популярностью пользуются книги Михаила Булгакова, 
на втором месте книги Сергея Есенина. Исходя из этого решили поднять цену книг Булгакова на 10%, 
а цену книг Есенина - на 5%. Написать запрос, куда включить автора, название книги и новую цену, 
последний столбец назвать new_price. 
начение округлить до двух знаков после запятой. 
SELECT author, title,
ROUND(if (author='Булгаков М.А.', price*1.1, if(author='Есенин С.А.', price*1.05, price)),2) as new_price
FROM book;


SELECT author, title, price
FROM book
WHERE amount < 10;

SELECT title, author, price, amount
FROM book
WHERE (price < 500 or price > 600) and (price * amount >= 5000);

SELECT title, author, price, amount
FROM book
WHERE price BETWEEN 540.50 AND 800 and (amount = 5 or amount = 7 or amount = 2 or amount = 3);

SELECT DISTINCT author
FROM book;

SELECT author, SUM(amount)
FROM book
GROUP BY author; */

INSERT INTO book (title, author, price, amount) VALUES ('Черный человек','Есенин С.А.', Null, Null);
INSERT INTO book (title, author, price, amount) VALUES ('Письмо женщине', 'Есенин С.А.', 1, 1);

/* SELECT author, COUNT(author), COUNT(amount), COUNT(*)
FROM book
GROUP BY author; 

SELECT author AS 'Автор', count(title) AS 'Различных_книг', sum(amount) AS 'Количество_экземпляров'
FROM book
GROUP BY author;

SELECT author, min(price) AS 'Минимальная_цена', max(price) AS 'Максимальная_цена', avg(price) AS 'Средняя_цена'
FROM book
GROUP BY author;


В запросы с групповыми функциями можно включать условие отбора строк,
которое в обычных запросах записывается после WHERE. 
В запросах с групповыми функциями вместо WHERE используется ключевое слово
HAVING , которое размещается после оператора GROUP BY.


SELECT author,
    MIN(price) AS Минимальная_цена, 
    MAX(price) AS Максимальная_цена
FROM book
GROUP BY author
HAVING SUM(price * amount) > 5000 
ORDER BY Минимальная_цена DESC;
*/

SELECT author, title, price
FROM book
WHERE price <= (
    SELECT avg(price)
    FROM book
)
ORDER BY price desc;

SELECT author, title, price
FROM book
WHERE price < ANY (SELECT min(price)
                   FROM book
                   GROUP BY author
);

created 2 years ago

MySQL online editor

Write, Run & Share MySQL queries online using OneCompiler's MySQL online editor and compiler for free. It's one of the robust, feature-rich online editor and compiler for MySQL. Getting started with the OneCompiler's MySQL editor is really simple and pretty fast. The editor shows sample boilerplate code when you choose language as 'MySQL' and start writing queries to learn and test online without worrying about tedious process of installation.

About MySQL

MySQL is a open-source, free and very popular relational database management system which is developed, distributed and supported by Oracle corporation.

Key Features:

Open-source relational database management systems.
Reliable, very fast and easy to use database server.
Works on client-server model.
Highly Secure and Scalable
High Performance
High productivity as it uses stored procedures, triggers, views to write a highly productive code.
Supports large databases efficiently.
Supports many operating systems like Linux*,CentOS*, Solaris*,Ubuntu*,Windows*, MacOS*,FreeBSD* and others.

Syntax help

Commands

1. CREATE

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

Example

CREATE TABLE EMPLOYEE (
  empId INTEGER PRIMARY KEY,
  name TEXT NOT NULL,
  dept TEXT NOT NULL
);

2. ALTER

ALTER TABLE Table_name ADD column_name datatype;

Example

INSERT INTO EMPLOYEE VALUES (0001, 'Dave', 'Sales');

3. TRUNCATE

TRUNCATE table table_name;

4. DROP

DROP TABLE table_name;

5. RENAME

RENAME TABLE table_name1 to new_table_name1;

6. COMMENT

Single-Line Comments:

 --Line1;

Multi-Line comments:

   /* Line1,
   Line2 */

DML Commands

1. INSERT

INSERT INTO table_name (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);

Note: Column names are optional.

Example

INSERT INTO EMPLOYEE VALUES (0001, 'Ava', 'Sales');

2. SELECT

SELECT column1, column2, ...
FROM table_name
[where condition];

Example

SELECT * FROM EMPLOYEE where dept ='sales';

3. UPDATE

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

Example

UPDATE EMPLOYEE SET dept = 'Sales' WHERE empId='0001';

4. DELETE

DELETE FROM table_name where condition;

Example

DELETE from EMPLOYEE where empId='0001';

Indexes

1. CREATE INDEX

  CREATE INDEX index_name on table_name(column_name);

To Create Unique index:

  CREATE UNIQUE INDEX index_name on table_name(column_name);

2. DROP INDEX

DROP INDEX index_name ON table_name;

Views

1. Create a View

Creating a View:
CREATE VIEW View_name AS 
Query;

2. How to call view

SELECT * FROM View_name;

3. Altering a View

ALTER View View_name AS 
Query;

4. Deleting a View

DROP VIEW View_name;

Triggers

1. Create a Trigger

CREATE TRIGGER trigger_name trigger_time trigger_event
    ON tbl_name FOR EACH ROW [trigger_order] trigger_body
/* where
trigger_time: { BEFORE | AFTER }
trigger_event: { INSERT | UPDATE | DELETE }
trigger_order: { FOLLOWS | PRECEDES } */

2. Drop a Trigger

DROP TRIGGER [IF EXISTS] trigger_name;

Stored Procedures

1. Create a Stored Procedure

CREATE PROCEDURE sp_name(p1 datatype)
BEGIN
/*Stored procedure code*/
END;

2. How to call Stored procedure

CALL sp_name;

3. How to delete stored procedure

DROP PROCEDURE sp_name;

Joins

1. INNER JOIN

SELECT * FROM TABLE1 INNER JOIN TABLE2 where condition;

2. LEFT JOIN

SELECT * FROM TABLE1 LEFT JOIN TABLE2 ON condition;

3. RIGHT JOIN

SELECT * FROM TABLE1 RIGHT JOIN TABLE2 ON condition;

4. CROSS JOIN

SELECT select_list from TABLE1 CROSS JOIN TABLE2;