Concept explainers
Given Crow Foot Relational Diagram:
Primary Key:
A Primary Key in a database table is a field in the table that uniquely identifies every row or record present in the database table.
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.
Many to Many Relationship:
When more than 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 many to many relationship. This is represented as m: n relationship where m and n are two entities.
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
- Use the following diagram relation to perform the normalization. You need to provide the 2NF and 3NF.arrow_forwardConsider the following schema: Suppliers (sid, sname, city) Parts (pid, pname, color) Catalog (sid, pid, price) Write relational algebra expressions for the following queries: a. Find the sids of suppliers and names who are located in Riyadh. b. Find the name of suppliers who are located in Riyadh and Jeddah. c. Find the names of supplier who supply part name "fog light". d. Find the sids of suppliers who supply every part.arrow_forwardConvert the ER diagram in the above question into relational model.arrow_forward
- what is relational model representation of ER/EER model? A)student(studentno,name,firstname,midinitials,lastname,phone) Primary key: studentno B)student(studentno,name,phone) Primary key: studentno C)student(studentno,name,firstname,lastname,phone) Primary key: studentno D)student(studentno,fistname,lastname,phone) Primary key: studentnoarrow_forwardQuestion 14 Consider the following schema and answer the following questions: Vendor (v ID: integer, v_Name: varchar, v_City: varchar) Product (p ID: integer, p_Name: varchar, p_colour: varchar) Catalog (v ID: integer, p ID: integer, Cost: decimal, Type: varchar) a. Write the following queries in relational algebra. i. Find the names of vendors who are from 'Suhar'. ii. Find the IDs of products which are supplied at cost greater than 1000. iii. Find IDs of vendors who supplies products with blue color.arrow_forwardUsing relation below y=y+pow(-x,i)/factorial(i) ;arrow_forward
- Consider the following schema: Suppliers (sid, sname, city) Parts (pid, pname, color) Catalog (sid, pid, price) Write relational algebra expressions for the following queries: 1. Find the sids of suppliers and names who are located in Riyadh. 2. Find the name of suppliers who are located in Riyadh and Jeddah. 3. Find the names of supplier who supply part name “fog light”. 4. Find the sids of suppliers who supply every part. please only answer point number 4arrow_forward1) The manager of an international company would like to know the quantity sold for each product and foreach store by day, week, month, and year. For each store, the manager would like to know its correspondingcity and country.You have to design a star schema to achieve the goal of this manager.2) If you think that some of your proposed dimension tables in Q1, are not normalized, you have to convertyour star schema into snowflake schema to normalize these dimension tables.arrow_forwardSuppose we have two tables. One table is Supplier with column supplieriD and ItemiD. The other table is Item, which has column ItemiD and Description. Which of the following returns itemiD for all items which are supplied by at least one supplier SELECT itemID FROM item WHERE EXISTS ( SELECT DISTINCT itemID FROM itemSupplier WHERE itemSupplier.itemID = item itemID) SELECT itemID FROM item WHERE itemID ( SELECT itemID FROM itemSupplier) IF EXISTS ( SELECT itemID FROM item Supplier) SELECT * FROM item SELECT itemID FROM item WHERE EXISTING ( SELECT DISTINCT itemID FROM itemSupplier) Given a table Students, to give each student a unique number based on credit hours he/she has obtained, which statement is correct? SELECT s.Name, s.CreditHours, ROW NUMBERO OVER (ORDER BY s.CreditHours DESC) AS 'Row Number From Students s SELECT s.Name, s.CreditHours, RANKO OVER (ORDER BY s.CreditHours DESC) AS Row Number From Studentss SELECT S.Name, s.CreditHours, DENSE RANKO OVER (ORDER BY s.CreditHours…arrow_forward
- Database Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781285196145Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos CoronelPublisher:Cengage LearningNp Ms Office 365/Excel 2016 I NtermedComputer ScienceISBN:9781337508841Author:CareyPublisher:Cengage
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