chapter 4
Normalization requires applications to use more complex SQL since they will need to write subqueries and joins to recombine data stored in separate relations.
true
Read-only databases often use several copies of a set of the same data, where each copy is modified for a specific use.
true
Relations are sometimes left unnormalized to improve performance.
true
Relations in BCNF have no modification anomalies regarding functional dependencies.
true
SQL statements that can be used to create referential integrity statements for normalized tables are created during the normalization process.
true
The INSERT statement can be used to populate normalized tables.
true
The IS NULL keyword can be used to count the number of nulls in a column.
true
The elimination of modification anomalies and the reduction of duplicated data are advantages of normalization.
true
The first step in assessing table structure is to count rows and examine columns.
true
The multivalue, multicolumn problem is just another form of a multivalued dependency.
true
The multivalued, multicolumn problem occurs when a set of columns are used to store data that should actually be in one column.
true
The presence of one or more foreign keys in a relation means that we cannot eliminate duplicated data in that table.
true
The problem with a general-purpose remarks column is that the data it contains are likely to be verbal, inconsistent, and stored in a verbose manner.
true
The second step in assessing table structure is to examine data values and determine dependencies and keys.
true
The third step in assessing table structure is to check the validity of presumed referential integrity constraints.
true
To limit the number of rows retrieved from a table, use the TOP keyword.
true
United States ZIP codes are a classic example of unneeded normalization.
true
When examining data values as a part of assessing table structure, determine functional dependencies.
true
When examining data values as a part of assessing table structure, determine multivalued dependencies.
true
When examining data values as a part of assessing table structure, determine the table's primary key.
true
When examining data values as a part of assessing table structure, determine three types of keys: the primary key, any candidate keys, and any foreign keys.
true
When examining data values as a part of assessing table structure, you should determine two types of dependencies: functional dependencies and multivalued dependencies.
true
When you are given a set of tables and asked to create a database to store their data, the first step is to assess the tables' structure and content.
true
Writing SQL subqueries and joins against normalized tables is simple compared to the code that must be written to handle anomalies from multivalued dependencies.
true
You have been given two tables, CUSTOMER and SALE. You want to check the referential integrity constraint: SALE.CustomerNumber must exist in CUSTOMER.CustomerNumber You run the following SQL query: SELECT CustomerNumber FROM SALE WHERE CustomerNumber NOT IN (SELECT CustomerNumber FROM CUSTOMER); What is shown in the results of this query? A) All values of CustomerNumber that match the constraint. B) All values of CustomerNumber that violate the constraint. C) All values of CustomerNumber where SALE.CustomerNumber = CUSTOMER.CustomerNumber. D) All values of Customer number that are in CUSTOMER but not in SALE.
B
To count the number of rows in a table, use the SQL construct ________. A) SELECT * B) SELECT TOP n * C) SELECT COUNT(TOP n) D) SELECT COUNT(*)
D
Read-only databases are used for ________. A) updating B) querying C) data entry D) user account management
`b
A classic example of unneeded normalization is when we are dealing with ________. A) ZIP codes B) sales orders and line items C) association patterns D) multivalued dependencies
a
A form of multivalued dependency is found in ________. A) the multivalued, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
a
A table with columns PhoneNumber01, PhoneNumber02, and PhoneNumber03 is likely to have ________. A) the multivalue, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
a
During the second step of assessing table structure, you are trying to determine ________. A) multivalued dependencies B) data types C) missing values D) subqueries
a
The advantages of normalization include ________. A) the elimination of modification anomalies B) the elimination of duplicated data C) more complex SQL for multitable subqueries and joins D) simpler SQL queries
a
When you are given a set of tables and asked to create a database to store their data, the first step is to ________. A) assess the existing tables' structure and content B) design the database structure C) create one or more new tables D) move the data into the new database
a
75) For a number of reasons, ________ is not often an advantage for a read-only database. A) updating B) normalization C) denormalization D) Both A and B are correct
b
A missing value is called a(n) ________. A) empty value B) null value C) missing value D) deleted value
b
A null value can indicate which of the following conditions? A) The value is incorrect. B) The value is appropriate but unknown. C) The value has been updated. D) The value can never be changed.
b
An advantage of denormalization is ________. A) faster updating B) faster querying C) faster copying of data D) faster design
b
During the second step of assessing table structure, you are trying to determine ________. A) relationships B) candidate keys C) updatability D) efficiency
b
Practical problems in designing databases from existing data include all of the following except ____________. A) The multivalue, multicolumn problem B) functional dependencies C) Inconsistent values D) Missing values
b
The SQL function COUNT ________. A) counts the number of columns in a table B) counts the number of rows in a table C) counts the number of tables in a database D) counts the number of updates to a database
b
The TOP keyword ________. A) limits the number of columns retrieved from a table B) limits the number of rows retrieved from a table C) limits the number of tables retrieved from a database D) A and C
b
The problem of misspelled data entries is really the same as ________. A) the multivalue, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
b
To limit the number of rows retrieved from a table, use ________. A) SELECT * B) SELECT TOP n * C) SELECT COUNT(TOP n) D) SELECT COUNT(*)
b
When a table is created using existing data from multiple sources, you are likely to find that the different sources code data in slightly different ways. This is an example of ________. A) the multivalued, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
b
You are creating a PRODUCT table using existing data from multiple sources. Examining the data, you find that you have "large red hat", "large hat, red", "red hat large" and "hat, large, red." This is an example of ________. A) the multivalued, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
b
Classification: Concept 68) The disadvantages of normalization include ________. A) the elimination of modification anomalies B) the elimination of duplicated data C) more complex SQL for multitable subqueries and joins D) Both A and B are correct
c
Reviewing the work done on a table that was created using existing data from multiple sources, you are likely to find that some data values that were provided were never entered into the table. This is an example of ________. A) the multivalued, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
c
The keyword IS NULL can be used to help ________. A) count the number of columns in a table B) count the number of rows in a table C) count the number of null values in a column D) count the number of values in a column
c
The second step in assessing table structure includes ________. A) counting rows B) examining columns C) examining data values D) A and B
c
To check for null values in a column in a table, use the ________ phrase. A) IS B) IS NOT C) IS NULL D) COUNT(NULL)
c
When a table is created using existing data from multiple sources, you are likely to find that some data values have never been provided because the values are not known. This is an example of ________. A) the multivalued, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
c
When a table is created using existing data, you are likely to find that some data values have never been provided because any value there would be inappropriate. This is an example of ________. A) the multivalued, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
c
_______ is the process of joining two or more tables and storing the result as a single table. A) Querying B) Normalization C) Denormalization D) Updating
c
Anomalies caused by functional dependencies can be eliminated by putting tables into ________. A) 1NF B) 2NF C) 3NF D) BCNF
d
Reviewing the work done on a table that was created using existing data from multiple sources, you find that a column named Remarks has been included, and it is populated with inconsistent and verbose verbal data. This is an example of ________. A) the multivalued, multicolumn problem B) the inconsistent values problem C) the missing values problem D) the general-purpose remarks column problem
d
The defining characteristic of BCNF is that a table is in BCNF if ________. A) all rows are unique B) all columns are consistent C) the primary key is a candidate key D) all determinants are candidate keys
d
The first step in assessing table structure includes ________. A) counting rows B) examining columns C) examining data values D) Both A and B are correct
d
Unlike the anomalies from functional dependencies, the anomalies from ________ are so serious that they should always be eliminated. A) general purpose remarks columns B) sales orders and line items C) association patterns D) multivalued dependencies
d
) General-purpose remarks columns rarely contain important data.
false
) To eliminate multivalued dependencies, normalize your tables so that they are all in BCNF.
false
Design guidelines and priorities are the same whether you're working with an updatable database or a read-only database.
false
Most DBMS products will let you define a primary key on a column that contains null values.
false
Normalization eliminates modification anomalies and data duplication.
false
Normalization is an advantage for a read-only database.
false
Read-only databases are often updated.
false
Read-only databases seldom use more than one copy of a set of the same data.
false
The DELETE TABLE statement can be used to remove unneeded tables after the normalized tables are created and populated.
false
The problem of misspelled data entries is an entirely different problem than the inconsistent values problem.
false
To count the number of rows in a table, use COUNT(ROWS).
false
To determine the number and type of columns in a table, use COUNT(*).
false
When examining data values as a part of assessing table structure, there is no need to determine candidate keys other than the table's primary key.
false
When examining data values as a part of assessing table structure, there is no need to determine foreign keys.
false
When you are creating a database from existing data, you will have only minor problems with inconsistent values.
false
) Null values are a problem because they are ambiguous.
true
A defining requirement for BCNF is that every determinant must be a candidate key.
true
A missing value is called a null value.
true
A null value in a column may indicate that there is an appropriate value for that attribute, and although the value is known, no one has entered the value into the database.
true
A null value in a column may indicate that there is an appropriate value for that attribute, but it is unknown.
true
A null value in a column may indicate that there is no appropriate value for that attribute.
true
An inconsistent values problem is created when different users have coded the same data entries differently.
true
Creating a read-only database is a job often given to beginning database professionals.
true
Database design varies depending on whether you're building an updatable database or a read-only database.
true
Denormalization involves joining the data together and storing it in a table.
true
Denormalization is the process of joining previously normalized tables back together.
true
Denormalization reduces the complexity of the SQL statements needed in an application to read required data.
true
If you have a table with a set of columns named "Child01", "Child02" and "Child03", the table is likely to have the multivalued, multicolumn problem.
true
If you see a column name Notes, it is likely that this is a general-purpose remarks column
true
Multivalued dependencies create anomalies that must always be eliminated.
true
Multivalued dependencies show up under a different name as the multivalued, multicolumn problem.
true
You are creating a BOAT table using existing data from multiple sources, and you find that you have "power boat blue", "boat, power, blue" and "blue power boat" as data values for the same column. This is an example of the inconsistent values problem.
true