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WGU D427 Objective Assessment final exam and
practice exam complete 300 questions covering data
modeling, SQL queries, database design,
normalization, and relational database management
systems.
What are the basic components of a table in a relational
database? - ANSWER-- A table has a name, a fixed sequence of
columns, and a varying set of rows. - A column has a name and a
data type. - A row is an unnamed sequence of values. Each value
corresponds to a column and belongs to the column's data type. -
A cell is a single column of a single row. - A table must have at
least one column but any number of rows. A table without rows
is called an empty table.
Refer to the Employee table. Identify a column name, a cell
value, and the components of a column. \nEmployee\nID Name
Salary\n2538 Lisa Ellison 45000\n5384 Sam Snead
30500\n6381 Maria Rodriguez 92300 - ANSWER-- Column
name: Salary - Cell value: 30500 - Components of a column:
Name and data type
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What are the four main rules that tables must obey in a relational
database? - ANSWER-1. Exactly one value per cell. A cell may
not contain multiple values. Unknown data is represented with a
special NULL value. 2. No duplicate column names. Duplicate
column names are allowed in different tables, but not in the
same table. 3. No duplicate rows. No two rows may have
identical values in all columns. 4. No row order. Rows are not
ordered. The organization of rows on a storage device, such as a
disk drive, never affects query results.
What is the principle of data independence? - ANSWER-The
principle of data independence states that the result of a database
query is not affected by the physical organization of data on
storage devices. This allows database administrators to improve
query performance by changing the organization of data on
storage devices without affecting query results.
How do most databases handle tables with duplicate rows, and
why might they allow duplicates temporarily? - ANSWER-Most
databases allow tables with duplicate rows in violation of the no
duplicate rows rule, but these tables are usually temporary. For
example, external data with duplicate rows might be loaded into
a temporary table, and the duplicate rows are normally
eliminated as data is moved to a permanent table.
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Write a SQL statement to create an Employee table with
columns ID (integer), Name (variable-length string with max 60
characters), BirthDate (date), and Salary (decimal with 7 digits
and 2 decimal places). - ANSWER-CREATE TABLE Employee
( ID INT, Name VARCHAR(60), BirthDate DATE, Salary
DECIMAL(7,2) );
Write a SQL statement to delete the Employee table. -
ANSWER-DROP TABLE Employee;
True or False: The statement `CREATE TABLE Employee (ID
INT, Name VARCHAR(60), BirthDate DATE, Salary
DECIMAL(7,2));` creates an Employee table with 4 columns. -
ANSWER-True
True or False: The Name column in the Employee table contains
character string values. - ANSWER-True
True or False: The statement `DROP TABLE Employee;` deletes
the Employee table. - ANSWER-True
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True or False: The DROP TABLE statement does not delete the
table unless the table is empty. - ANSWER-False. The table is
deleted regardless of how many rows are in the table.
Write a SQL statement to create a Product table with columns:
ID (integer), Name (variable-length string with max 40
characters), ProductType (variable-length string with max 3
characters), OriginDate (date), and Weight (decimal with 6
significant digits and 1 digit after the decimal point). -
ANSWER-CREATE TABLE Product ( ID INT, Name
VARCHAR(40), ProductType VARCHAR(3), OriginDate
DATE, Weight DECIMAL(6,1) );
What does the ALTER TABLE statement do, and what are the
three main clauses used with it? - ANSWER-The ALTER
TABLE statement adds, deletes, or modifies columns in an
existing table. The three main clauses are: 1. **ADD:** Adds a
column. ALTER TABLE TableName ADD ColumnName
DataType; 2. **CHANGE:** Modifies a column. ALTER
TABLE TableName CHANGE CurrentColumnName
NewColumnName NewDataType; 3. **DROP:** Deletes a
column. ALTER TABLE TableName DROP ColumnName;
Write a SQL statement to add a column called Description
(variable-length string with max 50 characters) to the
WGU D427 Objective Assessment final exam and
practice exam complete 300 questions covering data
modeling, SQL queries, database design,
normalization, and relational database management
systems.
What are the basic components of a table in a relational
database? - ANSWER-- A table has a name, a fixed sequence of
columns, and a varying set of rows. - A column has a name and a
data type. - A row is an unnamed sequence of values. Each value
corresponds to a column and belongs to the column's data type. -
A cell is a single column of a single row. - A table must have at
least one column but any number of rows. A table without rows
is called an empty table.
Refer to the Employee table. Identify a column name, a cell
value, and the components of a column. \nEmployee\nID Name
Salary\n2538 Lisa Ellison 45000\n5384 Sam Snead
30500\n6381 Maria Rodriguez 92300 - ANSWER-- Column
name: Salary - Cell value: 30500 - Components of a column:
Name and data type
,2|Page
What are the four main rules that tables must obey in a relational
database? - ANSWER-1. Exactly one value per cell. A cell may
not contain multiple values. Unknown data is represented with a
special NULL value. 2. No duplicate column names. Duplicate
column names are allowed in different tables, but not in the
same table. 3. No duplicate rows. No two rows may have
identical values in all columns. 4. No row order. Rows are not
ordered. The organization of rows on a storage device, such as a
disk drive, never affects query results.
What is the principle of data independence? - ANSWER-The
principle of data independence states that the result of a database
query is not affected by the physical organization of data on
storage devices. This allows database administrators to improve
query performance by changing the organization of data on
storage devices without affecting query results.
How do most databases handle tables with duplicate rows, and
why might they allow duplicates temporarily? - ANSWER-Most
databases allow tables with duplicate rows in violation of the no
duplicate rows rule, but these tables are usually temporary. For
example, external data with duplicate rows might be loaded into
a temporary table, and the duplicate rows are normally
eliminated as data is moved to a permanent table.
,3|Page
Write a SQL statement to create an Employee table with
columns ID (integer), Name (variable-length string with max 60
characters), BirthDate (date), and Salary (decimal with 7 digits
and 2 decimal places). - ANSWER-CREATE TABLE Employee
( ID INT, Name VARCHAR(60), BirthDate DATE, Salary
DECIMAL(7,2) );
Write a SQL statement to delete the Employee table. -
ANSWER-DROP TABLE Employee;
True or False: The statement `CREATE TABLE Employee (ID
INT, Name VARCHAR(60), BirthDate DATE, Salary
DECIMAL(7,2));` creates an Employee table with 4 columns. -
ANSWER-True
True or False: The Name column in the Employee table contains
character string values. - ANSWER-True
True or False: The statement `DROP TABLE Employee;` deletes
the Employee table. - ANSWER-True
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True or False: The DROP TABLE statement does not delete the
table unless the table is empty. - ANSWER-False. The table is
deleted regardless of how many rows are in the table.
Write a SQL statement to create a Product table with columns:
ID (integer), Name (variable-length string with max 40
characters), ProductType (variable-length string with max 3
characters), OriginDate (date), and Weight (decimal with 6
significant digits and 1 digit after the decimal point). -
ANSWER-CREATE TABLE Product ( ID INT, Name
VARCHAR(40), ProductType VARCHAR(3), OriginDate
DATE, Weight DECIMAL(6,1) );
What does the ALTER TABLE statement do, and what are the
three main clauses used with it? - ANSWER-The ALTER
TABLE statement adds, deletes, or modifies columns in an
existing table. The three main clauses are: 1. **ADD:** Adds a
column. ALTER TABLE TableName ADD ColumnName
DataType; 2. **CHANGE:** Modifies a column. ALTER
TABLE TableName CHANGE CurrentColumnName
NewColumnName NewDataType; 3. **DROP:** Deletes a
column. ALTER TABLE TableName DROP ColumnName;
Write a SQL statement to add a column called Description
(variable-length string with max 50 characters) to the
