https://github.com/moindalvs/excelr_data_analyst_sql_assignment_part3
1. Write a stored procedure that accepts the month and year as inputs and prints the ordernumber, orderdate and status of the orders placed in that month.
https://github.com/moindalvs/excelr_data_analyst_sql_assignment_part3
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1. Write a stored procedure that accepts the month and year as inputs and prints the ordernumber, orderdate and status of the orders placed in that month.
- Host: GitHub
- URL: https://github.com/moindalvs/excelr_data_analyst_sql_assignment_part3
- Owner: MoinDalvs
- Created: 2022-11-21T06:32:40.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2023-01-18T07:38:21.000Z (over 2 years ago)
- Last Synced: 2025-01-18T00:44:13.053Z (6 months ago)
- Size: 8.79 KB
- Stars: 5
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# SET 3
## [Download Link for SQL Database](https://raw.githubusercontent.com/MoinDalvs/EXCELR_Data_Analyst_SQL_Assignment_Part1/main/ConsolidatedTables.sql)
use assignment;
## 1. Write a stored procedure that accepts the month and year as inputs and prints the ordernumber, orderdate and status of the orders placed in that month.
-- Example: call order_status(2005, 11);
DELIMITER //
Create procedure order_status( IN t_year INT,
IN t_month INT )
BEGIN
select orderNumber,
orderdate,
status
from orders
where year(orderDate) = t_year
AND
month(orderDate) = t_month;
END //
DELIMITER ;
call order_status(2005, 4);
## 2. Write a stored procedure to insert a record into the cancellations table for all cancelled orders.
-- STEPS:
-- a. Create a table called cancellations with the following fields
-- id (primary key),
-- customernumber (foreign key - Table customers),
-- ordernumber (foreign key - Table Orders),
-- comments
-- All values except id should be taken from the order table.
-- b. Read through the orders table . If an order is cancelled, then put an entry in the cancellations table.
DELIMITER //
CREATE PROCEDURE cancelled_order( )
BEGIN
DROP TABLE IF EXISTS cancellation ;
CREATE TABLE cancellation
(
id int primary key auto_increment,
customerNumber int,
orderNumber int,
comments text,
FOREIGN KEY (customerNumber)
REFERENCES customers(customerNumber)
ON DELETE CASCADE,
FOREIGN KEY (orderNumber)
REFERENCES orders(orderNumber)
ON DELETE CASCADE
);
INSERT INTO cancellation ( customerNumber, orderNumber, comments)
SELECT customerNumber, orderNumber, comments
FROM orders
WHERE status = 'Cancelled';
SELECT *
FROM cancellation;
END //
DELIMITER ;
CALL cancelled_order();
-- ANOTHER APPROACH
DROP PROCEDURE IF EXISTS cancelled_order;
DELIMITER //
CREATE DEFINER=`root`@`localhost` PROCEDURE `cancelled_order`( )
BEGIN
CREATE TABLE IF NOT EXISTS cancellation
(
id int primary key auto_increment,
customerNumber int,
orderNumber int,
comments text,
FOREIGN KEY (customerNumber)
REFERENCES customers(customerNumber)
ON DELETE CASCADE,
FOREIGN KEY (orderNumber)
REFERENCES orders(orderNumber)
ON DELETE CASCADE
);
INSERT INTO cancellation ( customerNumber, orderNumber, comments)
SELECT customerNumber, orderNumber, comments
FROM orders
WHERE status = 'Cancelled' AND
NOT EXISTS ( select customerNumber, orderNumber, comments from cancellation );
SELECT *
FROM cancellation;
END //
DELIMITER ;
CALL cancelled_order();
## 3. a. Write function that takes the customernumber as input and returns the purchase_status based on the following criteria . [table:Payments]
-- if the total purchase amount for the customer is < 25000 status = Silver, amount between 25000 and 50000, status = Gold
-- if amount > 50000 Platinum
select *,
CASE
WHEN amount < 25000 THEN 'Silver'
WHEN amount BETWEEN 25000 AND 50000 THEN 'Gold'
ELSE 'Platinum'
END AS Status
from payments;
DELIMITER //
CREATE PROCEDURE customer_status( cust_No INT )
BEGIN
SELECT CASE
WHEN amount < 25000 THEN 'Silver'
WHEN amount BETWEEN 25000 AND 50000 THEN 'Gold'
ELSE 'Platinum'
END AS Status
from payments
where customerNumber = cust_No;
END //
DELIMITER ;
CALL customer_status( 103 );
-- b. Write a query that displays customerNumber, customername and purchase_status from customers table.
select c.customerNumber,
c.customerName,
o.status
from customers c
LEFT JOIN orders o
USING (customerNumber);
## 4. Replicate the functionality of 'on delete cascade' and 'on update cascade' using triggers on movies and rentals tables.
-- Note: Both tables - movies and rentals - don't have primary or foreign keys. Use only triggers to implement the above.
-- Q. For ON DELETE CASCADE, if a parent with an id is deleted, a record in child with parent_id = parent.id will be automatically deleted. This should be no problem.
-- 1. This means that ON UPDATE CASCADE will do the same thing when id of the parent is updated?
-- 2. If (1) is true, it means that there is no need to use ON UPDATE CASCADE if parent.id is not updatable (or will never be updated) like when it is AUTO_INCREMENT or always set to be TIMESTAMP. Is that right?
-- 3. If (2) is not true, in what other kind of situation should we use ON UPDATE CASCADE?
-- A. It's true that if your primary key is just an identity value auto incremented, you would have no real use for ON UPDATE CASCADE.
-- However, let's say that your primary key is a 10 digit UPC bar code and because of expansion, you need to change it to a 13-digit UPC bar code. In that case,
-- ON UPDATE CASCADE would allow you to change the primary key value and any tables that have foreign key references to the value will be changed accordingly.
-- In reference to #4, if you change the child ID to something that doesn't exist in the parent table (and you have referential integrity), you should get a foreign key error.
What if I (for some reason) update the child.parent_id to be something not existing, will it then be automatically deleted?
DELIMITER //
CREATE TRIGGER delete_cascade
AFTER DELETE on movies
FOR EACH ROW
BEGIN
UPDATE rentals
SET movieid = NULL
WHERE movieid
NOT IN
( SELECT distinct id
from movies );
END //
DELIMITER ;
drop trigger if exists delete_cascade;
select *
from movies;
INSERT INTO movies ( id, title, category )
Values ( 11, 'The Dark Knight', 'Action/Adventure');
INSERT INTO rentals ( memid, first_name, last_name, movieid )
Values ( 9, 'Moin', 'Dalvi', 11 );
delete from movies
where id = 11;
SELECT id
from movies;
SELECT *
from rentals;
DELIMITER //
CREATE TRIGGER update_cascade
AFTER UPDATE on movies
FOR EACH ROW
BEGIN
UPDATE rentals
SET movieid = new.id
WHERE movieid = old.id;
END //
DELIMITER ;
DROP trigger if exists update_cascade;
INSERT INTO movies ( id, title, category )
Values ( 12, 'The Dark Knight', 'Action/Adventure');
UPDATE rentals
SET movieid = 12
WHERE memid = 9;
UPDATE movies
SET id = 11
WHERE title regexp 'Dark Knight';
select *
from movies;
select *
from rentals;
## 5. Select the first name of the employee who gets the third highest salary. [table: employee]
select *
from employee
order by salary desc
limit 2,1;
## 6. Assign a rank to each employee based on their salary. The person having the highest salary has rank 1. [table: employee]
select *,
dense_rank () OVER (order by salary desc) as Rank_salary
from employee;