BITM 330
Synonym of tuple
Row
A surrogate key may be appropriate under which of the following circumstances?
The available candidate keys would produce a lot of data duplication when representing relationships The available candidate keys would be prone to typographical errors
Given the functional dependency for the attributes of ENTITY1,X --> (A,B,C), X is a candidate key for the relation ENTITY1 (A,B,C,X).
True
If the condition exists such that knowing the value of attribute X determines the value attribute Y, then attribute Y is functionally dependent on attribute X.
True
In the relational model, many-to-many relationships cannot be directly represented by relations the way 1:1 and 1:N relationships can
True
Surrogate key values have no meaning to the users.
True
IN MS access, the relationship between two tables isnt created until
the CREATE button in the edit relationships dialog box is clicked
In the normalization process if you find that every determinant in a relation is a candidate key, then you have determined that the relation is well formed
true
Null values can cause problems because they are ambiguous
true
Is the table Employee(Employee_ID, First_Name, Last_Name, Phone, Position_ID, Position_Description) in A) 1NF B) 2 NF C) 3 NF D) 4NF
2NF
In the normalization process, if you find a candidate key that is not a primary key, then you have determined that the relation needs to be broken into two or more other relations
False
In the normalization process, it is not necessary to identify all the functional dependencies in a relation
False
In the relational model, each row of a table contains data that represents an attribute of the entity
False
Normalization is the process of removing all functional dependencies from a relation
False
Since surrogate keys are used to uniquely identify rows, their values are normally displayed prominently on all forms and reports for the users to see
False
The use of surrogate keys usually complicates application programming since most DBMS products require the application program to generate surrogate key values.
False
1st step of the normalization process is to
Identify all the candidate keys of a relation
1st Normal Form (1NF)
each row/column intersection contains one and only one value, not a set of values; all attributes are dependent on the primary key
A key must be unique
false
Candidate keys may or may not be unique
false
In microsoft access, a relationship is created by dragging a foreign key column and dropping it on top of the corresponding primary key
false
In microsoft access, foreign keys are designated by using the foreign key button in the toolbar
false
Microsoft acces forms can only contain data from one table
false
When the primary key of one relation is placed into a second relation it is called a
foreign key
A rule that requires that the values in a foreign key must have a matching value in the primary key to which the foreign key corresponds is called
referential integrity constraint
A primary key is
required to be unique used to represent rows in a relationship a candidate key used to identify unique rows
A candidate key is
required to be unique used to represent rows in relationships a candidate to be the primary key
If every determinant in a relation is a candidate key thnen
the relation is well formed
Determinant
Any attribute in a specific row whose value directly determines other values in that row.
A stable that meets the requirements of a relation is said to be in whcih normal form? A) Relational normal form(RNF) B) First normal form C)Second normal form D)Boyce-Codd normal form E) Domain/key normal form
B
Which of the following is true about a relation A)The order of the columns in a relation must go from largest to smallest B) All entries in any column must be of the same kind C) A relation may have duplicate column names D) a relation may have duplicate rows E) a relation may have multiple names
B
In the normalization process, it is not necessary to A) identify all the candidate keys of a relation B)Identify all the foreign keys of a relation C) identify all the functional dependencies of a relation D) identify all the determinants of a relation E) determine if every determinant is a candidate key
B) Identify all the foreign keys of a relation
Any table that meets the definition of a relation is said to be in second normal form
False
When used to represent a relationship, the primary key must have the same name as the corresponding foreign key.
False
In SQL server the starting value of a surrogate key is called the
Identity seed
One to many relationship (1:M)
One thing can have many results ex. One customer can have many orders
Orders(Order_Id, BarCode, Quantity, Item_decription, Date_Purchased, SalesPerson_ID, SalesPerson_First, SalesPerson_Last)
Orders(Order_Id, Date_Purchased, SalesPerson_ID, SalesPerson_First, SalesPerson_Last) Items(BarCode, Item_decription) OrderLine (Order_Id, BarCode, Quantity) 2nf but not 3nf Orders(Order_Id, Date_Purchased, SalesPerson_ID) Items(BarCode, Item_decription) OrderLine (Order_Id, BarCode, Quantity) Sales_Persons(SalesPerson_ID, SalesPerson_First, SalesPerson_Last)
Synonym of relation
Table
To be considered a composite key, a key must contain at least two attributes
True
To create a well-formed relation through normalization, every determinant must be a candidate key.
True
one-to-one relationship (1:1)
a relationship between two entities in which an instance of one entity can be related to only one instance of a related entity ex. Each student has one ID
Every cell in a relation can hold only a single value
true
In microsoft access, relationships between tables are created in the relationships window
true
The first step of the normalization process is to identify all the candidate keys of a relation
true
The primary key is used both to identify unique rows in a relation and to represent rows in relationships
true
to represent a relationship in the relational model the primary key of one relation is placed into a second relation
true
Which split of the table from the question 5: Employee(Employee_ID, First_Name, Last_Name, Phone, Position_ID, Position_Description) is correct A)Employee(Employee_ID, First_Name, Last_Name, Phone, Position_ID) Position(Position_ID,Position_Description) B)Employee(Employee_ID, First_Name, Last_Name, Phone) Position(Position_ID,Position_Description) c)Employee(Employee_ID, First_Name, Last_Name, Phone) Position(Position_ID,Position_Description, Employee_ID)
A
3rd Normal Form (3NF)
A relation that is in 1NF and 2NF, and in which no non-primary key attribute is transitively dependent on the primary key. That is, all non-key elements are fully dependent on the primary key Cant have: column x depends on column y which depends upon the primary key z
2nd Normal Form (2NF)
A relation that is in 1NF and every non-primary key attribute is fully dependent on the primary key. That is, all the incomplete dependencies have been removed Partial Dependency Table: book_author (taken by book_ID and author_ID combined to make primary key) 1. book_ID 2. author_ID 3. author_position 4. ISBN ISBN is a partial dependency because it only references book_ID. Does not have anything to do with author_ID
Candidate Key
An attribute, or combination of attributes, that uniquely identifies a row in a relation.
In microsoft access referential integrity constraints are created
By checking the enforce referential integrity check box in the edit relationships dialog box
In microsoft access a relationship between two tables is created
By dragging the primary key column of one table onto the foreign key column of the other table in the relationships window
Which of the following is not true about a relation? A) a relation is a two dimensional table B) the cells of a relation must hold a single value C) A relation may have duplicate column names D) A relation may not have duplicate rows E) the order of the rows of a relation is insignificant
C
durring the normalization process, the remedy for a relation that is not well formed is to A)create a surrogate key B) create a functional dependency C) break it into two or more relations that are well formed D) Combine it with another relation that is well formed E) Convert it into a list
C
The first step in trnasforming an extended E-R model into a relational database design is to __________ A) Create a table for each relationship B) Evaluate the entities against the nromalization criteria C) Create a table for each entity D) Remove any recursive relationships E) Document Referential integrity constraints
C) Create a table for each entity
Refer t the database Premier Products with tables: Orders, Order_line, parts. Assume that table parts has attributes: Partnumber, Description, on_hand, Min_on_Hand and price. To create a price list for a super sales event with 10% discount you will reate a _______ and in the new field Sales_Price Put: _____ A) Table, Sales_Price:price *.10 B) Query, Sales_Price:price*0.10 C) Query, Sales_Price:price*0.90 D) Table, sales_price:price*0.90
C) Query, Sales_Price:price*0.90
Fourth Formal Form (4NF)
Cant have something with many possibilities Employee, skill_proficiency, Language_profficciency Employee 101 can do archery, badminton, darts. Employee 101 can speak chinese, german, french
A key that contains more than one attribute is called a(n):
Composite key
Find the PK for the table Employee(Employee_ID, First_Name, Last_Name, Phone, Position_ID, Position_Description)
Employee_ID
One important relational design principle is that
Every determinent must be a candidate key
In the normalization process, if you find a candidate key that is not a determinant then you should A) place the columns of the functional dependency in a new relation B) Make the determinant of the functional dependency the primary key of the new relation C) leave a copy of the determinant as a foreign key in the original relation D)all of the above E) none of the above
D) all of the above
Which of the following is not true about null values A)A null value can mean that the value is unknown B) the null value is ambiguous C) the null value can mean that the value is known to be blank D) a null value can mean that no value for the field is appropriate E) Null values cannot be avoided
E
Which of the following is true about a key A) It may be unique B) it may be non unique C) it may identify more that one row D) Both a and B E) All of the above
E
In the normalization process, if you find a candidate key that is not a primary key, then you should A) place the columns of the functional dependency in a new relation B) make the determinant of the functional dependency the primary key of the new relation C) leave a copy of the determinant as a foreign key in the original relation D) all of the above E) none of the above
E none of the above
A database may be used to help people: A) Track which student is assigned to a particular advisor B) Check on the estimated arrival time of an incoming flight at an airport C) Check on the eliminated arrival time of anincoming flight at an airport D) Look at their checking account balance over the internet E) All of the above
E) All of the above
Refer to the database Premier products with tables: Orders, Order_line, Parts. The reason for having a table parts may be: A) To list prices B) To present number of each item on hand C) To present current customers D) All of the Above E) Only A) and B)
E) Only A) and B)
Infinity symbol
The symbol that indicates the "many" side of a one-to-many relationship.
Which of the following is not true of surrogate keys A) meaningful to the users b) they are numeric C) usually generated by the dbms D) they are unique E) they are usually hidden on forms and reports
They are meaningful to the users
Every relation is a table, but not every table is a relation.
True
In microsoft access, relationships between tables are created
in the relationships window
many-to-many relationship (M:N)
is between two entities in which an instance of one entity is related to many instances of another and one instance of the other can be related to many instances of the first entity ex: Many students to many classes and many classes can have many students
