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) Beget an ER diagram control the subjoined top (Hint: At lowest unseparated wishy-washy being kind is implicated)-Control this training well-behaved-behaved example a blog plan (approve blogger.com), where there are abundant users which can feel divergent blogs. We nonproduction to example Users, their Blogs, the Postings on each blog, and the Dilates control each posting . . Control each user, we obey its username (identifier), password and Name, separated into restraintemost, intermediate, decisive Control each blog, we obey its id (identifier), designation, the determination it was begetd, and the sum of posts (which can be conducive); we too obey trail of which user begetd which blog; a blog is begetd by correspondently unseparated user, and a user can beget unseparated or past blogs Control each Posting, we obey its id (identifier), the blog it appertains to (postings appertain to correspondently unseparated blog, and blogs may feel naught or past postings), its term mark and its solution Control each Dilate, we obey its sum (which uniquely identifies dilates control the selfselfidentical posting, still attributeable total dilates in open), term mark and solution. We too obey trail the user who made the dilate (comments are made by correspondently unseparated user, and a user can effect . . . naught or past dilates), and the posting the dilate attributes to (comments attribute to correspondently unseparated posting, and postings can feel naught or past dilates) 4. (40 pts) Beget an ER diagram control the subjoined top (fields designated id are identifiers; HINT: Recursive analogy(s) are implicated]) . We nonproduction to example curriculum advertableice. We nonproduction to obey trail of programs, control which we feel its id, and abridgment, and a designation . We too obey trail of roads; control each road we obey its id, a designation, the sum of confidence hours, naught or past road objectives. . Each road appertains to naught or past programs, and a program earn feel unseparated or past roads; control each of the programs a road appertains to, we archives whether the road is required or elective control the program. * We obey trail of subjects; control each subject we obey its id and designation. . We obey trail of which road(s) shelter which subject(s). Each subject is sheltered in unseparated or past roads, and each road shelters naught or past subjects. We too obey trail of how abundant apposition hours the road includes control that subject . We too obey trail of whether a road has other roads as prerequisites. Each road could feel naught or past other roads as prerequisites and be a prerequisite control naught or past roads .

    Beget an ER diagram control the subjoined top – Control this training we’ll example a blog plan (approve blogger.com), where there are abundant users which can feel divergent blogs. We nonproduction to example Users, their Blogs, the Postings on each blog, and the Dilates control each posting. Control each user, we obey its username (identifier), password and Name, separated into restraintemost, intermediate, decisive. Control each blog, we obey its id (identifier), designation, the determination it was begetd, and the sum of posts (which can be conducive): we too obey trail of which user begetd which blog: a blog is begetd by correspondently unseparated user, and a user can beget unseparated or past blogs. Control each Posting, we obey its id (identifier), the blog it appertains to (postings appertain to correspondently unseparated blog, and blogs may feel naught or past postings), its term mark and its solution. Control each Dilate, we obey its sum (which uniquely identifies dilates control the selfselfidentical posting, still attributeable total dilates in open), term mark and solution. We too obey trail the user who made the dilate (comments are made by correspondently unseparated user, and a user can effect naught or past dilates), and the posting the dilate attributes to (comments attribute to correspondently unseparated posting, and postings can feel naught or past dilates) Beget an ER diagram control the subjoined top (fields designated id are identifiers: We nonproduction to example curriculum advertableice. We nonproduction to obey trail of programs, control which we feel its id, and abridgment, and a designation. We too obey trail of roads: control each road we obey its id, a designation, the sum of confidence hours, naught or past road objectives. Each road appertains to naught or past programs, and a program earn feel unseparated or past roads: control each of the programs a road appertains to, we archives whether the road is required or elective control the program. We obey trail of subjects: control each subject we obey its id and designation. We obey trail of which road(s) shelter which subject(s). Each subject is sheltered in unseparated or past roads, and each road shelters naught or past subjects. We too obey trail of how abundant apposition hours the road includes control that subject. We too obey trail of whether a road has other roads as prerequisites. Each road could feel naught or past other roads as prerequisites and be a prerequisite control naught or past roads.

    Expert Counterpart

     

    3. The underneath is the er diagram.

    In the aloft er diagram dilate being is the wishy-washy being. Accordingly if there is no postings there would be no dilates at total. Thus dilate is purely depends upon the posting being.

    4.

    Underneath is the required er diagram. In this prerequisite is a recursive analogy accordingly road earn feel prerequisite as another road singly. So we can determine that in er diagram as recursive analogy