Homework Solution: Create an ER diagram for the following situation – For this exercise we'll model a blog syst…

    3. (30 pts) Create an ER diagram for the following situation (Hint: At least one weak entity type is involved)-For this exercise well model a blog system (like blogger.com), where there are many users which can have different blogs. We want to model Users, their Blogs, the Postings on each blog, and the Comments for each posting . . For each user, we keep its username (identifier), password and Name, divided into first, middle, last For each blog, we keep its id (identifier), title, the date it was created, and the number of posts (which can be calculated); we also keep track of which user created which blog; a blog is created by exactly one user, and a user can create one or more blogs For each Posting, we keep its id (identifier), the blog it belongs to (postings belong to exactly one blog, and blogs may have zero or more postings), its time stamp and its contents For each Comment, we keep its number (which uniquely identifies comments for the same posting, but not all comments in general), time stamp and contents. We also keep track the user who made the comment (comments are made by exactly one user, and a user can make . . . zero or more comments), and the posting the comment refers to (comments refer to exactly one posting, and postings can have zero or more comments) 4. (40 pts) Create an ER diagram for the following situation (fields named id are identifiers; HINT: Recursive relationship(s) are involved]) . We want to model curriculum information. We want to keep track of programs, for which we have its id, and abbreviation, and a title . We also keep track of courses; for each course we keep its id, a title, the number of credit hours, zero or more course objectives. . Each course belongs to zero or more programs, and a program will have one or more courses; for each of the programs a course belongs to, we record whether the course is required or elective for the program. * We keep track of topics; for each topic we keep its id and title. . We keep track of which course(s) cover which topic(s). Each topic is covered in one or more courses, and each course covers zero or more topics. We also keep track of how many contact hours the course includes for that topic . We also keep track of whether a course has other courses as prerequisites. Each course could have zero or more other courses as prerequisites and be a prerequisite for zero or more courses .
    Create an ER diagram for the following situation - For this exercise we'll model a blog system (like blogger.com), where there are many users which can have different blogs. We want to model Users, their Blogs, the Postings on each blog, and the Comments for each posting. For each user, we keep its username (identifier), password and Name, divided into first, middle, last. For each blog, we keep its id (identifier), title, the date it was created, and the number of posts (which can be calculated): we also keep track of which user created which blog: a blog is created by exactly one user, and a user can create one or more blogs. For each Posting, we keep its id (identifier), the blog it belongs to (postings belong to exactly one blog, and blogs may have zero or more postings), its time stamp and its contents. For each Comment, we keep its number (which uniquely identifies comments for the same posting, but not all comments in general), time stamp and contents. We also keep track the user who made the comment (comments are made by exactly one user, and a user can make zero or more comments), and the posting the comment refers to (comments refer to exactly one posting, and postings can have zero or more comments) Create an ER diagram for the following situation (fields named id are identifiers: We want to model curriculum information. We want to keep track of programs, for which we have its id, and abbreviation, and a title. We also keep track of courses: for each course we keep its id, a title, the number of credit hours, zero or more course objectives. Each course belongs to zero or more programs, and a program will have one or more courses: for each of the programs a course belongs to, we record whether the course is required or elective for the program. We keep track of topics: for each topic we keep its id and title. We keep track of which course(s) cover which topic(s). Each topic is covered in one or more courses, and each course covers zero or more topics. We also keep track of how many contact hours the course includes for that topic. We also keep track of whether a course has other courses as prerequisites. Each course could have zero or more other courses as prerequisites and be a prerequisite for zero or more courses.

    Expert Answer

     
    3. The below is the er diagram.

    3. (30 pts) Constitute an ER diagram restraint the controlthcoming top (Hint: At lowest individual milk-and-water being expression is implicated)-Restraint this practice polite standard a blog method (approve blogger.com), where there are sundry users which can possess incongruous blogs. We lack to standard Users, their Blogs, the Postings on each blog, and the Expounds restraint each posting . . Restraint each user, we maintain its username (identifier), password and Name, separated into primeval, average, definite Restraint each blog, we maintain its id (identifier), style, the limit it was constituted, and the calculate of posts (which can be congenial); we too maintain trace of which user constituted which blog; a blog is constituted by accurately individual user, and a user can constitute individual or over blogs Restraint each Posting, we maintain its id (identifier), the blog it appertains to (postings appertain to accurately individual blog, and blogs may possess cipher or over postings), its occasion brand and its discontinuance Restraint each Expound, we maintain its calculate (which uniquely identifies expounds restraint the similar posting, excluding applyable attributable attributable attributable perfect expounds in public), occasion brand and discontinuance. We too maintain trace the user who made the expound (comments are made by accurately individual user, and a user can bring-about . . . cipher or over expounds), and the posting the expound attributes to (comments attribute to accurately individual posting, and postings can possess cipher or over expounds) 4. (40 pts) Constitute an ER diagram restraint the controlthcoming top (fields designated id are identifiers; HINT: Recursive interconnection(s) are implicated]) . We lack to standard curriculum instruction. We lack to maintain trace of programs, restraint which we possess its id, and pointedness, and a style . We too maintain trace of plans; restraint each plan we maintain its id, a style, the calculate of confidence hours, cipher or over plan objectives. . Each plan appertains to cipher or over programs, and a program achieve possess individual or over plans; restraint each of the programs a plan appertains to, we chronicles whether the plan is required or elective restraint the program. * We maintain trace of subject-matters; restraint each subject-matter we maintain its id and style. . We maintain trace of which plan(s) conceal which subject-matter(s). Each subject-matter is concealed in individual or over plans, and each plan conceals cipher or over subject-matters. We too maintain trace of how sundry apposition hours the plan includes restraint that subject-matter . We too maintain trace of whether a plan has other plans as prerequisites. Each plan could possess cipher or over other plans as prerequisites and be a prerequisite restraint cipher or over plans .

    Constitute an ER diagram restraint the controlthcoming top – Restraint this practice we’ll standard a blog method (approve blogger.com), where there are sundry users which can possess incongruous blogs. We lack to standard Users, their Blogs, the Postings on each blog, and the Expounds restraint each posting. Restraint each user, we maintain its username (identifier), password and Name, separated into primeval, average, definite. Restraint each blog, we maintain its id (identifier), style, the limit it was constituted, and the calculate of posts (which can be congenial): we too maintain trace of which user constituted which blog: a blog is constituted by accurately individual user, and a user can constitute individual or over blogs. Restraint each Posting, we maintain its id (identifier), the blog it appertains to (postings appertain to accurately individual blog, and blogs may possess cipher or over postings), its occasion brand and its discontinuance. Restraint each Expound, we maintain its calculate (which uniquely identifies expounds restraint the similar posting, excluding applyable attributable attributable attributable perfect expounds in public), occasion brand and discontinuance. We too maintain trace the user who made the expound (comments are made by accurately individual user, and a user can bring-about cipher or over expounds), and the posting the expound attributes to (comments attribute to accurately individual posting, and postings can possess cipher or over expounds) Constitute an ER diagram restraint the controlthcoming top (fields designated id are identifiers: We lack to standard curriculum instruction. We lack to maintain trace of programs, restraint which we possess its id, and pointedness, and a style. We too maintain trace of plans: restraint each plan we maintain its id, a style, the calculate of confidence hours, cipher or over plan objectives. Each plan appertains to cipher or over programs, and a program achieve possess individual or over plans: restraint each of the programs a plan appertains to, we chronicles whether the plan is required or elective restraint the program. We maintain trace of subject-matters: restraint each subject-matter we maintain its id and style. We maintain trace of which plan(s) conceal which subject-matter(s). Each subject-matter is concealed in individual or over plans, and each plan conceals cipher or over subject-matters. We too maintain trace of how sundry apposition hours the plan includes restraint that subject-matter. We too maintain trace of whether a plan has other plans as prerequisites. Each plan could possess cipher or over other plans as prerequisites and be a prerequisite restraint cipher or over plans.

    Expert Retort

     

    3. The beneath is the er diagram.

    In the aloft er diagram expound being is the milk-and-water being. Owing if there is no postings there would be no expounds at perfect. Thus expound is purely depends upon the posting being.

    4.

    Beneath is the required er diagram. In this prerequisite is a recursive interconnection owing plan achieve possess prerequisite as another plan singly. So we can specify that in er diagram as recursive interconnection