MODERN DATABASE MANAGEMENT EXAM
COMPLETE QUESTIONS WITH CORRECT
ANSWERS||ALREADY GRADED
1) composite key - ANSWER ✔ A primary key that consists of more
than one attribute.
2) secondary key - ANSWER ✔ one field or a combination of fields
for which more than one records may have the same combinations
of values. Also called a nonunique key.
3) data type - ANSWER ✔ a detailed coding scheme recognized b
system software, such as a DBMS for representing organizational
data.
4) join index - ANSWER ✔ An index on columns from two or more
tables that come from the same domain of values.
5) describe three ways to handle missing field values - ANSWER ✔
1. Substitute an estimate of the missing value. For ex. for a missing
sales value when computing monthly product sales, use a formula
involving the mean of the existing monthly sales value for that
product indexed by total sales for that month across all products.
6) 2. Track missing data so special reports and other systems elements
cause people to resolve unknown values quickly. Done by setting
up a trigger in the database. A trigger is a routine that will
, automatically execute when some event occurs or time period
passes. One trigger could log the missing entry to a file when a null
or other missing value is stored, and another could run periodically
to create a report of the contents of this log file.
7) 3.Perform sensitivity testing so that missing data are ignored unless
knowing a value might significantly change results. (e.g. if total
monthly sales for a particular salesperson are almost over threshold
that would make a difference in that person's compensation.) most
complex of the three methods.
8) explain why normalized relations may not comprise an efficient
physical implementation structure - ANSWER ✔ Efficient
processing of data depends on how close together related data are.
A fully normalized database usually creates a large number of
tables causing the queries and processing to run slow. Partially
normalized databases run much faster.
9) list three common situations that suggest that relations be
denormalized before database implementation - ANSWER ✔ 1.
Two entities with a one-to one relationship. 2. A many to many
relationship (associative entity) with nonkey attributes. 3. reference
data.
10) state nine rules of thumb for choosing indexes - ANSWER ✔
1. indexes are most useful on large tables.
11) 2. specify a unique index for the primary key of each table.
12) 3. Indexes are most useful for columns that frequently appear
in WHERE clauses of the SQL commands.
13) 4. Use an index for attributes referenced in ORDER BY
(sorting) and GROUP BY (categorizing) clauses.
, 14) 5. use an index when there is significant variety in the values
of an attribute.
15) 6. Before creating an index on a field with long values,
consider first creating a compressed version of the values and then
indexing on the coded version.
16) 7. If the key for the index is going to be used for determining
the location where the record will be stored, then the key for this
index should be a surrogate key so that the values cause records to
be evenly spread across the storage space.
17) 8. Check your DBMS for a limit, if any, on the number of
indexes allowable per table.
18) 9. Be careful of indexing attributes that have null values.
19) data administration - ANSWER ✔ A high-level function that
is responsible for the overall management of data resources in an
organization, including maintaining corporate-wide definitions and
standards.
20) database administration - ANSWER ✔ A technical function
that is responsible for physical database design and for dealing
with technical issues, such as security enforcement, database
performance, ad backup recovery.
21) two-phase locking protocol - ANSWER ✔ A procedure for
acquiring the necessary locks for a transaction in which all
necessary locks are acquired before any locks are released,
resulting in a growing phase when locks are acquired and shrinking
phase when they are released.
COMPLETE QUESTIONS WITH CORRECT
ANSWERS||ALREADY GRADED
1) composite key - ANSWER ✔ A primary key that consists of more
than one attribute.
2) secondary key - ANSWER ✔ one field or a combination of fields
for which more than one records may have the same combinations
of values. Also called a nonunique key.
3) data type - ANSWER ✔ a detailed coding scheme recognized b
system software, such as a DBMS for representing organizational
data.
4) join index - ANSWER ✔ An index on columns from two or more
tables that come from the same domain of values.
5) describe three ways to handle missing field values - ANSWER ✔
1. Substitute an estimate of the missing value. For ex. for a missing
sales value when computing monthly product sales, use a formula
involving the mean of the existing monthly sales value for that
product indexed by total sales for that month across all products.
6) 2. Track missing data so special reports and other systems elements
cause people to resolve unknown values quickly. Done by setting
up a trigger in the database. A trigger is a routine that will
, automatically execute when some event occurs or time period
passes. One trigger could log the missing entry to a file when a null
or other missing value is stored, and another could run periodically
to create a report of the contents of this log file.
7) 3.Perform sensitivity testing so that missing data are ignored unless
knowing a value might significantly change results. (e.g. if total
monthly sales for a particular salesperson are almost over threshold
that would make a difference in that person's compensation.) most
complex of the three methods.
8) explain why normalized relations may not comprise an efficient
physical implementation structure - ANSWER ✔ Efficient
processing of data depends on how close together related data are.
A fully normalized database usually creates a large number of
tables causing the queries and processing to run slow. Partially
normalized databases run much faster.
9) list three common situations that suggest that relations be
denormalized before database implementation - ANSWER ✔ 1.
Two entities with a one-to one relationship. 2. A many to many
relationship (associative entity) with nonkey attributes. 3. reference
data.
10) state nine rules of thumb for choosing indexes - ANSWER ✔
1. indexes are most useful on large tables.
11) 2. specify a unique index for the primary key of each table.
12) 3. Indexes are most useful for columns that frequently appear
in WHERE clauses of the SQL commands.
13) 4. Use an index for attributes referenced in ORDER BY
(sorting) and GROUP BY (categorizing) clauses.
, 14) 5. use an index when there is significant variety in the values
of an attribute.
15) 6. Before creating an index on a field with long values,
consider first creating a compressed version of the values and then
indexing on the coded version.
16) 7. If the key for the index is going to be used for determining
the location where the record will be stored, then the key for this
index should be a surrogate key so that the values cause records to
be evenly spread across the storage space.
17) 8. Check your DBMS for a limit, if any, on the number of
indexes allowable per table.
18) 9. Be careful of indexing attributes that have null values.
19) data administration - ANSWER ✔ A high-level function that
is responsible for the overall management of data resources in an
organization, including maintaining corporate-wide definitions and
standards.
20) database administration - ANSWER ✔ A technical function
that is responsible for physical database design and for dealing
with technical issues, such as security enforcement, database
performance, ad backup recovery.
21) two-phase locking protocol - ANSWER ✔ A procedure for
acquiring the necessary locks for a transaction in which all
necessary locks are acquired before any locks are released,
resulting in a growing phase when locks are acquired and shrinking
phase when they are released.
