Online shopping cart. Tarik Guelzim Graduate school of computer science at Monmouth University. CS517 Database management systems Project 2

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1 Tarik Guelzim Graduate school of computer science at Monmouth University CS517 Database management systems Project 2 Page 1 of 9

2 Database Schema Page 2 of 9

3 Table name Indexed fields reason Page 3 of 9

4 DDL for the schema above: 1: creating the inventory table: CREATE TABLE inventory ( stkid BIGINT(20) NOT NULL, count INTEGER(10) NOT NULL, PRIMARY KEY(stkid) 2: create the shopper table: CREATE TABLE shopper ( full_name VARCHAR(45) NOT NULL, mailing_addr VARCHAR(100) NOT NULL, shipping_addr VARCHAR(100) NOT NULL, phone INTEGER(10) NOT NULL, VARCHAR(45) NOT NULL, PRIMARY KEY(sid) 3: create the payment_account table: CREATE TABLE payment_account ( aid BIGINT(20) NOT NULL, card_num INTEGER(16) NOT NULL, type INTEGER(1) NOT NULL, exp_date DATETIME NOT NULL, PRIMARY KEY(aid, sid), FOREIGN KEY(sid) REFERENCES shopper(sid) 4: Create the cart table: CREATE TABLE cart ( cid BIGINT(20) NOT NULL, cname VARCHAR(45) NOT NULL, date_opened DATETIME NOT NULL, PRIMARY KEY(cid, sid), FOREIGN KEY(sid) REFERENCES shopper(sid) 5: create the item table Page 4 of 9

5 CREATE TABLE item ( pid BIGINT(20) NOT NULL, stkid BIGINT(20) NOT NULL, display_name VARCHAR(50) NOT NULL, pirce INTEGER(10) NOT NULL, description VARCHAR(200) NOT NULL, PRIMARY KEY(pid, stkid), FOREIGN KEY(stkid) REFERENCES inventory(stkid) 6: create the purchases tables CREATE TABLE purchases ( cid BIGINT(20) NOT NULL, pid BIGINT(20) NOT NULL, stkid BIGINT(20) NOT NULL, PRIMARY KEY(sid, cid, pid, stkid), FOREIGN KEY(cid, sid) REFERENCES cart(cid, sid) FOREIGN KEY(pid, stkid) REFERENCES item(pid, stkid) 7: Creating the payment table CREATE TABLE payment ( pyid BIGINT NOT NULL AUTO_INCREMENT, aid BIGINT(20) NOT NULL, amount INTEGER NOT NULL, date_proc DATETIME NOT NULL, PRIMARY KEY(pyid, sid, aid) 8: Creating cart_has_item table CREATE TABLE cart_has_item ( pid BIGINT(20) NOT NULL, cid BIGINT(20) NOT NULL, quantity INTEGER NULL, Page 5 of 9

6 Constraints of the database schema 1. a shopper can have multiple cart. 2. a cart can belong to only one shopper. 3. a cart can have many item. 4. an item can be in many carts 5. a shopper can have many payment accounts. 6. an account can only belong to one shopper. 7. an account can have many payments. 8. a payment can belong to only one account. 9. a cart can have many purchases. 10. a purchase can only belong to one cart. 11.an item can belong to many purchases 12. a purchase is one item. 13.an item can belong to one inventory. 14.an inventory can have multiple items. The diamonds implementation The diamonds in the above schema were either implanted as separate tables such in the case of the cart -> item relation or added as foreign keys in most cases to a table to preserve space such as in shopper->cart relation where instead of adding a third table(sid,cid) we added a foreign key(sid) in the cart table to link both tables. The diamonds were implemented in the DDL below when creating the entire schema. The following notion was used when designing the schema [1, *] : is a one to many relationship [*, 1] : is a many to one relationship [1, 1]: is a one to one relationship Each of the above notations was placed next to each table to describe its relation to the other table that is participating in the same relation. Page 6 of 9

7 SQL actions N.B: The following SQL code has been tested only on the MySQL database running an innodb engine. Creating a new shopper s account. /*This requires inserting a record in the shopper table and a record in the payment_acount table. We also need to make sure that the foreign key (FK) sid in payment_account is the same as the primary key (PK) of the shopper. INSERT INTO shopper (sid, full_name, mailing_addr, shipping_addr, phone, ) VALUES( NULL, tarik, 203 xyz, 203 xyz, , xyz@bb.com /*Inserting a NULL value in the sid field will force the DB to pick a random insert id and put it in it since the table s DDL defined the field as NOT NULL. := LAST_INSERT_ID( /* the above stmt retrieves the value that the db inserted instead of the NULL in the sid field, we are going to insert it in The sid FK of the payment_account table to link both of them INSERT INTO payment_account (aid, sid, card_num, type, exp_date) , 1, Creating a shopping cart /* creating a shopping cart requires inserting a record in the cart table and making sure that the sid FK matches the shopper. /*First we retrieve the sid of shopper Tarik for example, and save it in a variable := sid from shopper where full_name= tarik ; /* now that we have the sid of Tarik we insert it in the sid FK of the cart table INSERT INTO cart (cid, sid, cname, date_opened) VALUES( xmas, Purchasing an item /* purchasing an item requires that the item belongs to a cart Page 7 of 9

8 /* first we get the pid for let s say the item dell 5160 := pid from item where display_name= dell 5160 ; /*check if the item is in stock Select pid, count from item, inventory where item.pid=@pid; /*if the count is > 0 then execute the rest /* now we need the sid of the shopper := sid from shopper where full_name= tarik ; /* the cid of the xmas cart for shopper tarik := cid from cart where sid=@sid and cname= xmas ; /*now we insert the purchase in purchase table INSERT INTO purchases (sid, cid, pid) Updating the inventory when an item was purchased /* assuming that the item was purchased and we have the stkid and the count from inventory >0 Update inventory set count = count -1 where stkid = Viewing information about an item /*assuming we have the item s pid Select all from item; Deleting an item from a cart /* assuming we have the cid of the cart and the pid of the item Delete from cart_has_item where cid= and pid= 1154 ; /*increment the count in the inventory Update inventory set count=count+1 where stkid= 135 Inserting a record in the payment table Page 8 of 9

9 /*first we need the total amount of the purchases in a cart from purchases, item where purchases.pid = item.pid and cart.cid = 1222 /*update the payment table Insert into payment values (NULL, 123, 1,@sum,NULL Viewing all carts for shopper byrne whose sid is 222 Select cname, date_opened from cart where sid = 222 Viewing the content of a cart whose cid = 446 Select pid, quantity, display_name, price, (quantity*price) as total from cart_has_item as cc, item as i where cc.pid = i.pid order by total ascendant Adding an item to cart (not to final checkout order) /*assuming that we have the pid =23 of the item NOTE: that is most online shopping carts, the stock check isn t done until the item is queued for purchase or checkout, so no update to the inventory table is made INSERT INTO cart_has_item (pid, cid, quantity) VALUES( 23, 1222, 4 Page 9 of 9