
Primary Key:
A Primary Key in a
Example:
Students in Universities are assigned a unique registration number.
Therefore, in a STUDENT database table, the attribute “reg_no” acts as primary key.
Foreign Key:
Foreign Key is a column in a relational database table which provides a relation between two tables. It provides a cross reference between tables by pointing to primary key of another table.
Example:
In STUDENT database table, the attribute “reg_no” acts as primary key and in COURSE database table in which the student selects his or her course, the same “reg_no” acts as foreign key for the STUDENT table.
One to Many Relationship:
When one record in a database table is associated with more than one record in another table, the relationship between the two tables is referred as one to many relationship. It is also represented as1: M relationship. This is the opposite of many to one relationship.
ENTITY- RELATIONSHIP DIAGRAM (ERD):
Entity- Relationship Diagram is also known as ER Diagram. It is used to define the conceptual view of the database as viewed by the end user. It is used to depict the database’s main components: entities, relationships and attributes.
CROW FOOT ERD:
The Crow Foot ERD is an Entity Relationship Diagram which is used to represent the cardinalities present in the basic ER diagram. It is used to represent the relationships present between two tuples or tables present in the database.

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Chapter 3 Solutions
Database Systems: Design, Implementation, & Management
- 1. Create a Person.java file. Implement the public Person and Student classes in Person.java, including all the variables and methods in the UMLS. Person -name: String -street: String -city: String +Person(String name, String, street, String, city) +getName(): String +setName(String name): void +getStreet(): String +setStreet(String street): void +getCity(): String +setCity(String City): void +toString(): String Student -Id: int +Person(String name, String, street, String, city, int Id) +getId(): int +setId(int Id): void +toString(): String 2. Create a StudentTest.java file. Implement a public StudentTest class with a main method. In the main method, create one student object and print the object using System.out.println(). Your printing result must follow the example output: name: Mike, street: Morris Ave, city: Union, Id: 1000 Hint: You need to modify the toString methods in the Student class and Person class!arrow_forward1) Apply the Paint Blue algorithm discussed in class to the following Finite Automata. a a a b b a COIS-3050H-R-W01-2025WI-COMB Formal Languages & Automata a b Show the status of the Finite Automata at the conclusion of the Paint Blue Algorithm (mark the visited states with an X and only include edges that have not been followed). 2) Use the pumping lemma to prove the following language is nonregular: L= {ab} = {abbb, aabbbbbb, aaabbbbbbbbb, ...}arrow_forward3) Find CFGs that for these regular languages over the alphabet Σ= {a, b}. Draw a Finite Automata e CFG. 1 COIS-3050H-R-W01-2025WI-COMB Formal anguages & Automata Is that contain the substring aba. (b) The language of all words that have an odd number letters and contains the string bb. (c) The language of all words that begin with the substring ba and contains an odd number of letters. 4) Convert the following FA into a PDA. a a S± b a a Ν Ꮓarrow_forward
- COIS-3050H-R-W01-2025WI-COMB Formal ministic PDA. Are the following words accepted by this Languages & Automata UI MIUSɩ that aTU I ed, indicate which state the PDA is in when the crash occurs. (a) aabbaa (b) aaabab (c) bababa Start (d) aaaabb A Accept Read₁ Push a (e) aaaaaa a b Read, Popi a a,b A Read₂ Accept A Pop₂arrow_forward5) Eliminate the A-productions from the following CFG: Abc COIS-3050H-R-W01-2025WI-COMB Formal Languages & Automata BAabC C CaA | Bc | A 6) Convert the following CFG into CNF. S→ XYZ XaXbS | a |A YSbS | X | bb Z→ barrow_forwardNeed help answering these questions!1. Design a While loop that lets the user enter a number. The number should be multiplied by 10, and the result stored in a variable named product. The loop should iterate as long as the product contains a value less than 100. 2. Design a For loop that displays the following set of numbers: 0, 10, 20, 30, 40, 50 . . . 1000 3. Convert the While loop in the following code to a Do-While loop: Declare Integer x = 1 While x > 0 Display "Enter a number." Input x End Whilearrow_forward
- Need help with these:Design a While loop that lets the user enter a number. The number should be multiplied by 10, and the result stored in a variable named product. The loop should iterate as long as the product contains a value less than 100. 2. Design a For loop that displays the following set of numbers: 0, 10, 20, 30, 40, 50 . . . 1000 3. Convert the While loop in the following code to a Do-While loop: Declare Integer x = 1 While x > 0 Display "Enter a number." Input x End Whilearrow_forwardConvert the While loop in the following code to a Do-While loop: Declare Integer x = 1 While x > 0 Display "Enter a number." Input x End Whilearrow_forwardPython - need help creating a python program that will sum the digits of a number entered by the user. For example if the user inputs the value 243 the program will output 9 because 2 + 4 + 3 = 9. The program should ask for a single integer from the user, it should then calculate the sum of all the digits of that number and output the result.arrow_forward
- I need help with this in Python (with flowchart): Im creating a reverse guessing game. Then to choose a random number from 1 to 100 and the computer program will attempt to guess it, displaying the directions calculated or not. The guess will be displayed and the user will answer if it was correct or not. If correct, the game ends, if not then the computer asks if the guess was too high or too low. Finally inputting an answer and the computer generates a new guess within the proper range. Oh and to make sure the program doesnt guess outside of the ranges produced by the inputs of “too high” and “too low”. The program ending when the user guesses correctly or after the program takes 6 guesses. HELP ASAP!arrow_forwardI need help with this in Python (with flowchart): Im creating a reverse guessing game. Then to choose a random number from 1 to 100 and the computer program will attempt to guess it, displaying the directions calculated or not. The guess will be displayed and the user will answer if it was correct or not. If correct, the game ends, if not then the computer asks if the guess was too high or too low. Finally inputting an answer and the computer generates a new guess within the proper range. Oh and to make sure the program doesnt guess outside of the ranges produced by the inputs of “too high” and “too low”. The program ending when the user guesses correctly or after the program takes 6 guesses. HELP ASAP!arrow_forwardNeed help finding errors in my pseudocode (Two)! Declare Boolean finished = False Declare Integer value, cube While NOT finished Display "Enter a value to be cubed." Input value; Set cube = value^3 Display value, " cubed is ", cube End While Next, I intended the following pseudocode to display the numbers 1 through 60, and then display the message "Time’s up!". Doesnt work and has error. Declare Integer counter = 1 Const Integer TIME_LIMIT = 60 While counter < TIME_LIMIT Display counter Set counter = counter + 1 End While Display "Time's up!"arrow_forward
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