 
CREATE TABLE customers (
  customer_id INT PRIMARY KEY,
  name VARCHAR(50),
  email VARCHAR(50)
);

INSERT INTO customers (customer_id, name, email)
VALUES (1, 'John Smith', '[email protected]'),
       (2, 'Jane Doe', '[email protected]'),
       (3, 'Bob Johnson', '[email protected]');


CREATE TABLE orders (
  order_id INT PRIMARY KEY,
  customer_id INT,
  order_date DATE,
  FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
);

INSERT INTO orders (order_id, customer_id, order_date)
VALUES (1, 1, '2023-10-01'),
       (2, 2, '2023-10-05'),
       (3, 3, '2023-10-10');


CREATE TABLE categories (
  category_id INT PRIMARY KEY,
  category_name VARCHAR(50)
);

INSERT INTO categories (category_id, category_name)
VALUES (1, 'Category 1'),
       (2, 'Category 2');

CREATE TABLE products (
  product_id INT PRIMARY KEY,
  product_name VARCHAR(50),
  price DECIMAL(10, 2),
  category_id INT,
  FOREIGN KEY (category_id) REFERENCES categories(category_id)
);

INSERT INTO products (product_id, product_name, price, category_id)
VALUES (1, 'Product A', 10.00, 1),
       (2, 'Product B', 20.00, 2),
       (3, 'Product C', 30.00, 1),
       (4, 'Product D', 40.00, 2);



CREATE TABLE order_items (
  order_id INT,
  product_id INT,
  quantity INT,
  FOREIGN KEY (order_id) REFERENCES orders(order_id),
  FOREIGN KEY (product_id) REFERENCES products(product_id)
);

INSERT INTO order_items (order_id, product_id, quantity)
VALUES (1, 1, 2),
       (NULL, 2, 1),
       (2, 3, 3),
       (3, 4, 2),
       (3, 1, 1);
       
       
SELECT customers.name, SUM(order_items.quantity * products.price) AS total_spent
FROM customers
INNER JOIN orders
ON customers.customer_id = orders.customer_id
INNER JOIN order_items
ON orders.order_id = order_items.order_id
INNER JOIN products
ON order_items.product_id = products.product_id
GROUP BY customers.customer_id;
       
SELECT customers.name, customers.email, orders.order_date
FROM customers
INNER JOIN orders
ON customers.customer_id = orders.customer_id;
       
SELECT products.product_name
FROM products
LEFT JOIN order_items
ON products.product_id = order_items.product_id
WHERE order_items.order_id IS NULL;

SELECT name
FROM customers
WHERE customer_id IN (
  SELECT orders.customer_id
  FROM orders
  WHERE order_date < DATE_SUB(NOW(), INTERVAL 30 DAY)
);

SELECT product_name
FROM products
WHERE product_id IN (
  SELECT product_id
  FROM order_items
  GROUP BY product_id
  HAVING COUNT(*) > 1
);

created 1 year ago by Tejas _

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;