AP CSA |U2 L3 Attributes by Mr. B

Which of these relational operators are part of the JOIN operator? Select all that apply.

• SELECT

• PROJECT

• PRODUCT

• UNION

Which of these are part of the rule of entity integrity? Select all that apply.

• Primary keys must have unique tuples.

• Primary keys cannot have null values.

• Primary keys can only have one attribute.

• Prime attributes must be the first attributes in a table.

What is Instance Variables

• Variables defined in a class, but not in constructors

• Variables of a class that are shared between it’s instances

• The blueprint/definer of objects and contain functions, called methods available only to objects of that type

• Encapsulates instance attributes

Address is a good name for an Entity

• True

• False

Instances must always be mandatory

• True

• False

Consider a table 'students' with three attributes: 'student_id', 'last_name', and 'first_name'. Assume some students have the same last name, and some students have the same first name. How many candidate keys are there?

• two

• three

• four

• five

What is a subclass

• Tests out code and can run with errors

• Where the class gains attributes and methods of another

• Argument defined as variables under a function

• A type a class that is specified under a normal class, inheriting the features of the normal class

What is an exception

• Runs in a try block no matter if an error is raised or not

• Tests out code and can run with errors

• Either a built in or user defined class that are called either by the user or the program when a error happens

• Makes the code think the specified error/variable is in there

The <img> tag is empty, it contains attributes only, and does not have a closing tag.

• True

• False

Entity-Relationship Diagrams are incapable of being perceived by the senses

• True

• False