Module 2-3: Relational Models

Which of the following fields would be the best candidate for a primary key field in a table of employee data?

EmployeeID

A relational database handles entities, attributes, and relationships by storing each entity in its own row.

False

In relational algebra, what command is used to identify certain columns?

PROJECT

Based on the following table, which relational algebra command creates a new table named CustState containing the fields CustomerNum and State?

PROJECT Customer OVER (CustomerNum, State) GIVING CustState

In relational algebra, which command retrieves rows from a table based on specified criteria?

SELECT

Based on the following notation, which relational algebra command would list all information from the table concerning the customer with numeric CustomerNum 260?

SELECT Customer WHERE CustomerNum=260 GIVING Answer

Which aggregate function do you use to total the values in a numeric field in a group of records?

Sum

The attributes of an entity become the fields or columns in a table.

True

A _____ is a question about the data structured in a way that the DBMS can recognize and process.

query

The field you use to sort records is called the _____.

sort key

Which database term refers to a row in a table?

tuple

If you use ____________________ criteria, each criterion must be true for a record to be selected.

AND

How are aggregate functions different from other types of functions?

Aggregate functions make calculations on groups of records.

What type of query could you run to remove records with a product ID of 702 from the Products table?

delete query

What do you call the field used to join two tables on the "many" side of a one-to-many relationship?

foreign key field

Which of the following criteria selects all records containing a value greater than 250?

>250

If you are creating a computed field that adds 10 percent to the UnitPrice field, how do you enter the UnitPrice field name in the expression?

[UnitPrice]

What type of functions are Count, Sum, Avg, Max, and Min?

aggregate

A ____________________ in a record is the result of a calculation using data from the rest of the record.

computed field

When you can determine the value of a field using information from existing fields in a record in a query, you should create a(n) _____.

computed field