A. 1 How many primary key in the Flight entity? B. 5 How many tables in the system can Customer table

Why is the relational model important?

Question # 1: Consider the relational database of Figure 1. Write SQL Queries for each of below scenarios: a. Find the names of all employees who live in city "Miami". b. Find the names of all employees whose salary is greater than S100,000. c. Find the names of all employees who live in "Miami" and whose salary is greater than $100,000. employee (personname, street, city) works (person_name, company_name, salary) соmpany (compaулате, сity)

6. Show the structure of the DEPT table. Select all data from the DEPT table. Name Null? Туре DEPTNOΟ NUMBER(2) DNAME VARCHAR2(14) LỌC VARCHAR2(13) DEPTNO DNAME LOC 10 ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON

24. A relation is considered a: a. Column b. one-dimensional table c. two-dimensional table d. three-dimensional table

25. In the relational model, relationships between relations or tables are created by using: a. composite keys b. determinants c. candidate keys d. foreign keys

Please help am struggling. Thank you   1. Which of the following is not used to change a COLUMN in an TABLE?   a. ADD     b. MODIFY     c. DELETE     d. DROP   Which of the following statements best defines cardinality?   a. Cardinality expresses the maximum number of entity occurrences associated with one occurrence of the related entity.     b. Cardinality expresses the minimum number of entity occurrences associated with one occurrence of the related entity.     c. Cardinality expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.     d. Cardinality expresses number of entity occurrences associated with one occurrence of the related entity.

Consider the following table schemas (primary keys are underlined):  Company (cID, name, location)  Flight (cID, fnumber, departure, arrival, price:integer, numberOfSeats:integer)  Book (bID, cID, fnumber, customerID, seat, date)  Customer (customerID, name, address)    Draw Query-By-Example (QBE) tables for the following queries.    1.Find the names and addresses of customers who never booked a flight.  2. Find the names of customers who booked the flight to New York more than  once.  3.Find the names of the companies that have the biggest (in terms of the  number of seats) airplane.  4. Find the names of customers who booked flights to Boston and  Seattle.  5. Insert tuples into a new table CustomerCheck that stores the names and  addresses of customers along with their flight numbers who booked a flight from  New York to LA on 09/30/21. Note: Query by example table is needed not just any table

What are the performance implications of frequently using JOIN operations on large tables in databases?

1- For each table, identify the primary key and the foreign key(s). If a table does not have a foreign key, write None. 2. Do the tables exhibit entity integrity? Answer yes or no, and then explain your answer. 3. Do the tables exhibit referential integrity? Answer yes or no, and then explain your answer. Write NA (Not Applicable) if the table does not have a foreign key