Infoman Midterms Flashcards
Each table in a relational database must have a primary key. [T/F]
True
A data dictionary contains metadata—data about data.[T/F]
True? (Google answer) (canvas answer =False)
A proper understanding of the concept and use of keys in a relational database model is very important. [T/F]
True
You can think of a table as a persistent representation of a logical relation.[T/F]
True
There is never a good reason to use null values in a database.[T/F]
False? (Google answer) (canvas answer =True)
Numeric data are data on which you can perform meaningful arithmetic procedures.[T/F]
True
All RDBMSs enforce integrity rules automatically[T/F]
False (Many RDBMS not all)
Character data can contain any character or symbol intended for mathematical manipulation. [T/F]
False
A data dictionary is sometimes described as “the database designer’s database” because it records the
design decisions about tables and their structures. [T/F]
True
The order of the rows and columns is important to the DBMS.[T/F]
False
Depending on the sophistication of the application development software with DBMS, nulls can create problems
when functions such as COUNT, AVERAGE, and SUM are used.[T/F]
True
Because the relational model uses attribute values to establish relationships among tables, many
database users correctly assume that the term relation refers to such relationships. .[T/F]
False
The practical significance of taking the logical view of a database is that it serves as a reminder of the
simple file concept of data storage. [T/F]
True
Referential and entity integrity are two names for the same thing. [T/F]
False
DBMSs use indexes for many different purposes.
True
The relational database model enables you to view data ____ rather than ____.
logically, phisically
____ data can have only a true or false (yes or no) values.
Logical
A ____ key can be described as a superkey without nnecessary attributes, that is, a minimal superkey.
candidate
Any attribute that is part of a key is known as a ____.
key attribute
Referential ____ means that if the foreign key contains a value, that value refers to an existing valid
tuple (row) in another relation.
Integrity
Controlled ____ makes a relational database work
redundancy
A ____ is any key that uniquely identifies each row
superkey
A(n) ____ is perceived as a two-dimensional structure composed of rows and columns.
table
The relational model’s creator, E. F. Codd, used the term relation as a synonym for ____.
table
A ____ key is defined as a key that is used strictly for data retrieval purposes.
secondary
In the relational model, ____ are important because they are used to ensure that each row in a table is
uniquely identifiable
keys
All primary key entries are unique, and no part of a primary key may be ____.
null
A CUSTOMER table’s primary key is CUS_CODE. The CUSTOMER primary key column has no
null entries, and all entries are unique. This is an example of ____ integrity.
entity
No data entry at all is known as a(n) ____.
null
In the following table description, ____ is the primary key.
PRODUCT (PROD_CODE, PROD_DESCRIPT, PROD_PRICE, PROD_ON_HAND,
VEND_CODE)
PROD_CODE
If one department chair—a professor—can chair only one department and one department can have
only one department chair, then the entities PROFESSOR and DEPARTMENT exhibit a(n)
____________________ relationship.
1:1
The ____________________ catalog can be described as a detailed system data dictionary that
describes all objects within the database, including data about table names, the table’s creator and
creation date, the number of columns in each table, the data type corresponding to each column,
index filenames, index creators, authorized users, and access privileges.
system
A(n) ____________________provides a detailed description of all tables found within the
user/designer-created database.
data dictionary
In a relational table, each column has a specific range of values known as the
____________________ domain.
attribute
The following example exhibits ____________________ integrity:
The CUSTOMER table’s primary key is CUS_CODE. The CUSTOMER primary key column has no
null entries, and all entries are unique. Similarly, the AGENT table’s primary key is AGENT_CODE,
and this primary key column also is free of null entries.
entity
The purpose of the MAX function in SQL is to select a specific number of rows from a table. [T/F]
False
The purpose of the MIN function in SQL is to return the maximum in a column of data. [T/F]
False
The BETWEEN keyword is used in conjunction with the Order By clause to limit the number of rows returned in a query. [T/F]
False
The purpose of the IN function in SQL is to select data that matches a set of values. [T/F]
True
You cannot use aggregate functions in the WHERE clause of a SQL query because aggregate functions can only be used in the SELECT clause. [T/F]
True
Functions that perform calculations on multiple rows of data and return a single result are called aggregate functions. [T/F]
True
A nested query is a query that is contained within another query. [T/F]
True
SELECT column1 FROM table1 WHERE column2 IN (SELECT column2 FROM table2) is a valid syntax. [T/F]
True
The more important field in sorting two columns is called major sort key.[T/F]
True
SELECT * FROM table ORDER BY column1 LIMIT 5, 10;
is a valid syntax for using the LIMIT clause in SQL [T/F]
True
The WHERE keyword is used to create a nested query in SQL. [T/F]
True
The purpose of DISTINCT function is to to return all unique values from a column. [T/F]
True
The purpose of the COUNT function is too count the number of rows in a table or the number of non-null values in a column. [T/F]
True
Basic Join is a type of join can be used in a nested query in SQL. [T/F]
True
The GROUP BY statement comes after any WHERE statements, but before ORDER BY or LIMIT. [T/F]
True
This function will display the current year:
EXTRACT(YEAR FROM curdate()); [T/F]
True
The query statement below returns the average number of downloads for an app in our database.
SELECT AVE(DOWNLOADS)
FROM APPS; [T/F]
True
The SUM aggregate function will you use when you include the asterisk(*) to represent all columns. [T/F]
False
%M date formats will display the month name? [T/F]
True
Comma (,) operators can be used in conjunction with the Order By clause to sort by multiple columns. [T/F]
True
