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-- Mar 17 In-Class Exercise

USERS(USERID, USERNAME, EMAIL, PASSWORD) POST(POSTID, USERID, POST, POPULARITY) USERID → USERNAME, EMAIL, PASSWORD POSTID → USERID, POST, POPULARITY Yes this is BNCF

-- Mar 17 In-Class Exercise

CREATE TABLE Users (
	uid INT PRIMARY KEY,
	fname STRING,
	lname STRING

)

CREATE TABLE Posts (
	pid INT PRIMARY KEY,
	uid INT REFERENCES Users(uid),
	content STRING,
	popularity INT,
	timestamp DATE

)

Functional Dependencies:
Users
uid → (fname, lname)
Posts
pid → (uid, content, popularity, timestamp)

Is this in BCNF?
Yes, because the left side of each FD is a key for the table.(Edited: 2021-03-17)

<pre> CREATE TABLE Users ( uid INT PRIMARY KEY, fname STRING, lname STRING ) </pre> <pre> CREATE TABLE Posts ( pid INT PRIMARY KEY, uid INT REFERENCES Users(uid), content STRING, popularity INT, timestamp DATE ) </pre> Functional Dependencies: Users uid → (fname, lname) Posts pid → (uid, content, popularity, timestamp) Is this in BCNF? Yes, because the left side of each FD is a key for the table.

-- Mar 17 In-Class Exercise

users(user number, username, password)

posts(post number, username, content, popularity)

user number -> username, password

post number -> username, content, popularity

(Edited: 2021-03-17)

users(user number, username, password) posts(post number, username, content, popularity) user number -> username, password post number -> username, content, popularity

-- Mar 17 In-Class Exercise

USER(USERNAME, EMAIL, PASSWORD), POST(POST_ID, CONTENT, POPULARITY), POSTED_BY(USERNAME, POST_ID)

EMAIL --> USERNAME PASSWORD --> USERNAME CONTENT --> POST_ID POPULARITY --> POST_ID POST_ID --> USERNAME

USER(USERNAME, EMAIL, PASSWORD), POST(POST_ID, CONTENT, POPULARITY), POSTED_BY(USERNAME, POST_ID) EMAIL --> USERNAME PASSWORD --> USERNAME CONTENT --> POST_ID POPULARITY --> POST_ID POST_ID --> USERNAME

-- Mar 17 In-Class Exercise

Create TABLE users (user_id integer, l_name varchar(30) not null, f_name varchar(30) not null, post varchar(255)); Create Table posts(post_id integer, thumbsup integer not null)

post_id --> thumbsup, post, post_id user_id --> f_name, l_name, user_id It could be BCNF.

(Edited: 2021-03-17)

Create TABLE users (user_id integer, l_name varchar(30) not null, f_name varchar(30) not null, post varchar(255)); Create Table posts(post_id integer, thumbsup integer not null) post_id --> thumbsup, post, post_id user_id --> f_name, l_name, user_id It could be BCNF.

-- Mar 17 In-Class Exercise

 USER(UNAME, EMAIL, POST_ID)
 POST_ID(POST_DATE, POST_DATA, POPULARITY)
 UNAME, EMAIL--> POST_ID
 UNAME--> EMAIL
 POST_ID--> UNAME, EMAIL
 POST_ID--> POST_DATE, POST_DATA, POPULARITY
 Tables are in BCNF because all non-trivial FD fix all rows.

(Edited: 2021-03-17)

USER(UNAME, EMAIL, POST_ID) POST_ID(POST_DATE, POST_DATA, POPULARITY) UNAME, EMAIL--> POST_ID UNAME--> EMAIL POST_ID--> UNAME, EMAIL POST_ID--> POST_DATE, POST_DATA, POPULARITY Tables are in BCNF because all non-trivial FD fix all rows.

-- Mar 17 In-Class Exercise

users(user_id(int), username(string), password_hash(string)) posts(post_id(int), user_id(int), content(string), upvotes(int)) user_id --> username, password_hash post_id --> user_id, content, likes Tables are in BCNF because all non-trivial functional dependencies fix all rows for each table

(Edited: 2021-03-17)

<nowiki> users(user_id(int), username(string), password_hash(string)) posts(post_id(int), user_id(int), content(string), upvotes(int)) user_id --> username, password_hash post_id --> user_id, content, likes Tables are in BCNF because all non-trivial functional dependencies fix all rows for each table </nowiki>

-- Mar 17 In-Class Exercise

USER(UID, USERNAME, PASSWORD) POST(PID, UID, POST_TEXT, THUMBSUP) UID → USERNAME, PASSWORD PID → USERID, POST_TEXT, THUMBSUP

-- Mar 17 In-Class Exercise

------TABLES----------
USERID = string
USERNAME = string
EMAIL = string
PASSWORD = string
POSTID = int
TEXT = string
POPULARITY = int 
 
USER(USERID, USERNAME, EMAIL, PASSWORD)
POSTS(USERID, POSTID, TEXT, POPULARITY) 
 
---FUNCTIONAL DEPENDENCIES----------
USERID --> USERNAME, PASSWORD, EMAIL
POSTID --> USERID, TEXT, POPULARITY

(Edited: 2021-03-17)

<pre> ----------TABLES---------- USERID = string USERNAME = string EMAIL = string PASSWORD = string POSTID = int TEXT = string POPULARITY = int USER(USERID, USERNAME, EMAIL, PASSWORD) POSTS(USERID, POSTID, TEXT, POPULARITY) ---FUNCTIONAL DEPENDENCIES---------- USERID --> USERNAME, PASSWORD, EMAIL POSTID --> USERID, TEXT, POPULARITY </pre>

-- Mar 17 In-Class Exercise

User(user_id, username, password, email) with primary key is user_id

Post(post_id, post_content, likes, user_id) with primary key is post_id

user_id --> username, password, email

post_id --> post_content, likes, user_id

These tables are in BCNF because they don't cause any redundancy

(Edited: 2021-03-17)

User(user_id, username, password, email) with primary key is user_id Post(post_id, post_content, likes, user_id) with primary key is post_id user_id --> username, password, email post_id --> post_content, likes, user_id These tables are in BCNF because they don't cause any redundancy