Update Lecture.sql

static/Session04/Lecture.sql

@@ -1,7 +1,10 @@
+# Use the database
 use comp353lab;
 
+# drop the target tables if exists
 drop table if exists customers, orders;
 
+# Creating of the tables + Insertion of the date to them
 create table customers(
     id int primary key auto_increment,
     first_name varchar(50),
@@ -37,45 +40,56 @@ insert into orders(customer_id, amount, created_at, ship_to)
                     (2, 500, '1999-02-02 22:00:00.000000', 'Iran'),
                     (1, 100, '2002-02-02 09:00:00.000000', 'Denmark');
 
+# Eliminate all of the customer with lower balance than 1500
 delete from customers
 where customers.balance<1500;
 
 
+# Update all of the Customers with country of Denmark to Turkey
 update customers
 set customers.country = 'Turkey'
 where customers.country = 'Denmark';
 
-select *
+# See all of the customers
+select customers.id, customers.country
 from customers;
 
-select *
+# Fetch all of the order with id of 1, 3, or 6
+select orders.id, orders.amount, orders.ship_to
 from orders
 where id in (1, 3, 6);
 
+# Alternative way to implement the above command
 select *
 from orders
 where id=1 or id=3 or id=6;
 
+# Fetch all of the countries (orders and customers tables)
 select customers.country
 from customers
 union
 select orders.ship_to
 from orders;
 
-select orders.amount
+# Fetch all of the order with amount in range of 350 and 550
+select orders.id, orders.amount
 from orders
 where amount between 350 and 550;
 
-
-select *
+# See all of the customers
+select customers.id, customers.country, customers.first_name, customers.last_name
 from customers;
 
-select *
+# Set limit
+select customers.id, customers.country, customers.first_name, customers.last_name
 from customers
 limit 2;
 
-select *
+# Set Limit with offset
+select customers.id, customers.country, customers.first_name, customers.last_name
 from customers
 limit 2
 offset 1;
 
+
+