Deck 8: Database Redesign

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سؤال
Although correlated subqueries are useful in database redesign,they cannot be used to verify functional dependencies.
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سؤال
A doubly nested set of NOT EXISTS SELECT statements can be used to find rows that meet some specified condition for every row in a table.
سؤال
In a correlated subquery,the same table is used in the upper and lower SELECT statements.
سؤال
Database redesign is rarely needed because databases are usually built correctly the first time.
سؤال
The use of a doubly nested set of NOT EXISTS SELECT statements is a famous pattern in SQL use.
سؤال
Correlated subqueries can be used to verify functional dependencies.
سؤال
In the SQL statement:
SELECT S1.CustName,S1.SalesRepNo FROM SALES S1;
the "S1" is called an alias.
سؤال
EXISTS and NOT EXISTS are actually just another form of correlated subqueries.
سؤال
In a correlated subquery,the DBMS can run the lower SELECT statement by itself and then send the results to the upper SELECT statement.
سؤال
In the database redesign process,two SQL tools are useful for testing whether or not certain conditions or assumptions are valid: uncorrelated subqueries and EXISTS/NOT EXISTS.
سؤال
There is a common trap in writing a correlated subquery,which will cause no rows to ever be displayed in the results.
سؤال
Database redesign is equally difficult whether or not the database has data in it.
سؤال
In a correlated subquery,the DBMS must run the lower SELECT statement as a process that is nested within the upper SELECT statement.
سؤال
In a real sense,information systems and organizations do not just influence each other,but rather they create each other.
سؤال
A continuous circular process of changes in user behaviors and change in the information systems they use is a natural outcome of information system use.
سؤال
When using queries with EXISTS and NOT EXISTS,the processing of the associated SELECT statements must be nested.
سؤال
Because EXISTS and NOT EXISTS are forms of correlated subqueries,the processing of the associated SELECT statements must be nested.
سؤال
In the database redesign process,it is often useful to test whether certain conditions or assumptions are valid before proceeding with the redesign.
سؤال
A correlated subquery looks very different from a noncorrelated subquery.
سؤال
The continuous circular process of changes is known as the Systems Development Life Cycle (SDLC).
سؤال
The NOT EXISTS keyword will be true if any row in the subquery fails to meet the condition.
سؤال
A means must be created to recover all test databases to their original state during the redesign testing process.
سؤال
Typically,there are at least four different copies of the database schema used in the redesign process.
سؤال
There is no good SQL command that can be used to change table names.
سؤال
The authors refer to the data model produced by reverse engineering as the RE data model.
سؤال
In order to minimize the need to change table names,some organizations have a policy that no user or application should ever employ the true name of a table,but use views as table aliases instead.
سؤال
SQL Server 2014 contains a system-stored procedure named sp_rename that can be used to change table names.
سؤال
A doubly nested set of EXISTS SELECT statements can be used to find rows that meet some specified condition for every row in a table.
سؤال
Changing table names is complicated by the fact that constraints and triggers are often associated with the table and will also need to be changed.
سؤال
SQL contains an SQL command RENAME TABLENAME that can be used to change table names.
سؤال
Dependency graphs are graphical displays like bar charts.
سؤال
The use of a doubly nested set of NOT EXISTS SELECT statements is so rare that even if you are a professional database developer you will probably never see it used.
سؤال
The data model produced by reverse engineering may include some entities that should not appear in the data model.
سؤال
The process of reading an actual database schema and producing a data model from that schema is called reverse engineering.
سؤال
When using a doubly nested set of NOT EXISTS SELECT statements,a row that does not match any row matches every row.
سؤال
Because of the need to know the functional dependencies in a database,it is a good idea to create a dependency graph.
سؤال
The design produced by reverse engineering may be described as a table-relationship diagram.
سؤال
Even if an organization has a very large database,it will be possible to make a complete backup copy of the operational database prior to making structural changes.
سؤال
The data model produced by reverse engineering is a true conceptual schema.
سؤال
The EXISTS keyword will be true if any row in the subquery meets the condition.
سؤال
To drop a foreign key column from a table,no preliminary steps are needed and we can simply use the ALTER TABLE DROP COLUMN statement.
سؤال
To drop a constraint,no preliminary steps are needed and we can simply use the ALTER TABLE DROP CONSTRAINT statement.
سؤال
Deleting tables and relationships is basically a matter of dropping foreign key constraints and then dropping the tables.
سؤال
To drop a nonkey column from a table,no preliminary steps are needed and we can simply use the ALTER TABLE DROP COLUMN statement.
سؤال
In the database redesign process,before proceeding with the redesign it is often useful to ________.

A)check whether certain conditions or assumptions about the data are valid
B)find out why the design was not done properly the first time
C)stop information systems and users from influencing each other
D)set standards for user behavior
سؤال
Adding new tables and relationships to a database is difficult.
سؤال
To drop a primary key column from a table the primary key constraint must first be dropped,but this does not require that related foreign keys based on the column be dropped.
سؤال
Depending on the DBMS,when changing the minimum cardinality on the parent side from zero to one,the foreign key constraint that defines the relationship may have to be dropped before the change is made and re-added afterwards.
سؤال
Converting date,money,or other more specific data types to char or varchar will usually succeed.
سؤال
There are several difficulties with increasing cardinalities from 1:1 to 1:N,one of which is preserving the existing relationships.
سؤال
Database redesign is fairly easy when ________.

A)information systems and organizations influence each other
B)the design was done correctly the first time
C)there is no data in the database
D)good backups of the database are available
سؤال
When increasing cardinalities from 1:N to N:M,we basically create a new intersection table,fill it with data and drop the old foreign key.
سؤال
Which of the following is not a possible step in the database redesign process?

A)Checking whether certain conditions or assumptions about the data are valid
B)Reverse engineering the data model
C)Revising user account name policies
D)Maintaining backups of the existing database
سؤال
In the database redesign process,an SQL tool that is useful for testing whether or not certain conditions or assumptions are valid is ________.

A)UPDATE
B)DROP TABLE
C)CREATE TRIGGER
D)NOT EXISTS
سؤال
When decreasing maximum cardinalities,there will always be data loss.
سؤال
In a correlated subquery of a database that has tables TableOne and TableTwo,if table TableOne is used in the upper SELECT statement,then which table is used in the lower SELECT statement?

A)TableOne
B)TableTwo
C)Both TableOne and TableTwo
D)Either TableOne or TableTwo
سؤال
To add a NULL column to a table,we simply use the MODIFY TABLE statement.
سؤال
If a DEFAULT constraint is included when a new column is added to a table,the default value is only applied to new rows and not to the existing rows at the time the new column is added.
سؤال
To change the minimum cardinality on the parent side from zero to one,the foreign key,which would have been NULL,must be changed to NOT NULL.
سؤال
To add a NOT NULL column to a table,we first add a NULL column,then we insert values into every row,and finally we change the NULL constraint to NOT NULL.
سؤال
In a doubly nested set of NOT EXISTS SELECT statements,________.

A)if a row does not not match any row,then it matches every row
B)if a row matches any row,then it matches every row
C)if a row does not match any row,then it does not match every row
D)if a row matches any row,then it does not match every row
سؤال
The data model produced by reverse engineering is a(n)________.

A)conceptual schema
B)internal schema
C)dependency graph
D)table-relationship diagram
سؤال
A doubly nested set of NOT EXISTS SELECT statements is ________.

A)a famous pattern in SQL
B)regularly used
C)rarely used to nonexistent in the real world
D)Both A and B are correct
سؤال
When running an SQL query that uses EXISTS,the EXISTS keyword will be true if ________.

A)any row in the subquery meets the condition
B)all rows in the subquery meet the condition
C)no row in the subquery meets the condition
D)any row in the subquery fails to meet the condition
سؤال
To add a NULL column to a table,we ________.

A)use the REVISE TABLE command
B)use the ALTER TABLE command
C)use the MODIFY TABLE command
D)create a new table with the NULL column,move the other data,and drop the old table
سؤال
If a DEFAULT constraint is included when a new column is added to a table,the default value is applied to ________.

A)all existing rows at the time the column is added
B)all new rows
C)all new rows but only after the UPDATE command is issued
D)Both A and B are correct
سؤال
When running a correlated subquery,the DBMS ________.

A)runs the lower SELECT statement by itself and then sends the results to the upper SELECT statement.
B)runs the upper SELECT statement by itself and then sends the results to the lower SELECT statement.
C)alternates running the lower SELECT statement with running the upper SELECT statement based on each result of the lower SELECT statement
D)Either A or B may be used depending on the query.
سؤال
In order to make sure the database redesign is working properly during the redesign testing process,a means must be created to ________.

A)reverse engineer all test databases
B)graph dependencies in all test databases
C)recover all test databases to their original state
D)re-interview all relevant users
سؤال
The data model produced by reverse engineering is not truly a logical model because it will contain ________.

A)tables for strong entities
B)supertype/subtype tables
C)tables for ID-dependent entities
D)intersection tables
سؤال
In the SQL statements SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1;
The "C1" is called a(n)________.

A)term
B)alias
C)convention
D)label
سؤال
A dependency graph should include all of the following except ________.

A)tables
B)views
C)triggers
D)DEFAULT values
سؤال
Which of the following different copies of the database schema is typically not used in the database redesign process?

A)Small test database
B)Data warehouse database
C)Operational database
D)Large test database
سؤال
When running a correlated subquery,the DBMS always uses ________.

A)regular processing
B)nested processing
C)"quick and dirty" processing
D)SQL-92 processing
سؤال
The process of reading an actual database schema and producing a data model from that schema is called ________.

A)data modeling
B)data engineering
C)reverse engineering
D)schema modeling
سؤال
Which of the following SQL statements is a correctly stated correlated subquery?

A)SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1
WHERE C1.SalesRepNo IN
(SELECT S1.SalesRepNo
FROM SALESREP S1
WHERE S1.RepName = 'Smith');
B)SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1
WHERE C1.SalesRepNo IN
(SELECT S1.SaleRepNo
FROM SALESREP S1
WHERE S1.RepName = 'Smith')
AND C1.SalesRepNo=S1.SalesRepNo);
C)SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1
WHERE C1.SalesRepNo IN
(SELECT S1.SaleRepNo
FROM SALESREP S1
WHERE S1.RepName = 'Smith')
AND C1.SalesRepNo<>S1.SalesRepNo);
D)SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1
WHERE C1.SalesRepNo IN
(SELECT C2.SaleRepNo
FROM CUSTOMER C2
WHERE C1.SalesRepNo=C2.SalesRepNo);
AND C1.OrderNo<>C2.OrderNo);
سؤال
SQL queries that use EXISTS and NOT EXISTS are ________.

A)normal subqueries
B)correlated subqueries
C)uncorrelated subqueries
D)constraint dependent subqueries
سؤال
Because of the need to know the functional dependencies in a database,it is a good idea to create a(n)________.

A)conceptual schema
B)internal schema
C)dependency graph
D)table-relationship diagram
سؤال
To change a table name,we ________.

A)use the SQL RENAME TABLE command
B)use the SQL ALTER TABLENAME command
C)use the SQL MODIFY TABLENAME command
D)create a new table,move the data,and drop the old table
سؤال
When making any change to the database structure,we may need to check for effects of the change on any of the following except ________.

A)data
B)foreign keys
C)ad-hoc SQL queries
D)triggers
سؤال
When running an SQL query that uses NOT EXISTS,the NOT EXISTS keyword will be true if ________.

A)any row in the subquery meets the condition
B)all rows in the subquery meet the condition
C)no row in the subquery meets the condition
D)any row in the subquery fails to meet the condition
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ملء الشاشة (f)
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Deck 8: Database Redesign
1
Although correlated subqueries are useful in database redesign,they cannot be used to verify functional dependencies.
False
2
A doubly nested set of NOT EXISTS SELECT statements can be used to find rows that meet some specified condition for every row in a table.
True
3
In a correlated subquery,the same table is used in the upper and lower SELECT statements.
True
4
Database redesign is rarely needed because databases are usually built correctly the first time.
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5
The use of a doubly nested set of NOT EXISTS SELECT statements is a famous pattern in SQL use.
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6
Correlated subqueries can be used to verify functional dependencies.
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7
In the SQL statement:
SELECT S1.CustName,S1.SalesRepNo FROM SALES S1;
the "S1" is called an alias.
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8
EXISTS and NOT EXISTS are actually just another form of correlated subqueries.
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9
In a correlated subquery,the DBMS can run the lower SELECT statement by itself and then send the results to the upper SELECT statement.
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10
In the database redesign process,two SQL tools are useful for testing whether or not certain conditions or assumptions are valid: uncorrelated subqueries and EXISTS/NOT EXISTS.
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11
There is a common trap in writing a correlated subquery,which will cause no rows to ever be displayed in the results.
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12
Database redesign is equally difficult whether or not the database has data in it.
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13
In a correlated subquery,the DBMS must run the lower SELECT statement as a process that is nested within the upper SELECT statement.
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14
In a real sense,information systems and organizations do not just influence each other,but rather they create each other.
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15
A continuous circular process of changes in user behaviors and change in the information systems they use is a natural outcome of information system use.
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16
When using queries with EXISTS and NOT EXISTS,the processing of the associated SELECT statements must be nested.
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17
Because EXISTS and NOT EXISTS are forms of correlated subqueries,the processing of the associated SELECT statements must be nested.
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18
In the database redesign process,it is often useful to test whether certain conditions or assumptions are valid before proceeding with the redesign.
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19
A correlated subquery looks very different from a noncorrelated subquery.
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20
The continuous circular process of changes is known as the Systems Development Life Cycle (SDLC).
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21
The NOT EXISTS keyword will be true if any row in the subquery fails to meet the condition.
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22
A means must be created to recover all test databases to their original state during the redesign testing process.
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23
Typically,there are at least four different copies of the database schema used in the redesign process.
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24
There is no good SQL command that can be used to change table names.
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25
The authors refer to the data model produced by reverse engineering as the RE data model.
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26
In order to minimize the need to change table names,some organizations have a policy that no user or application should ever employ the true name of a table,but use views as table aliases instead.
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27
SQL Server 2014 contains a system-stored procedure named sp_rename that can be used to change table names.
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28
A doubly nested set of EXISTS SELECT statements can be used to find rows that meet some specified condition for every row in a table.
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29
Changing table names is complicated by the fact that constraints and triggers are often associated with the table and will also need to be changed.
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30
SQL contains an SQL command RENAME TABLENAME that can be used to change table names.
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31
Dependency graphs are graphical displays like bar charts.
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32
The use of a doubly nested set of NOT EXISTS SELECT statements is so rare that even if you are a professional database developer you will probably never see it used.
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33
The data model produced by reverse engineering may include some entities that should not appear in the data model.
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34
The process of reading an actual database schema and producing a data model from that schema is called reverse engineering.
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35
When using a doubly nested set of NOT EXISTS SELECT statements,a row that does not match any row matches every row.
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36
Because of the need to know the functional dependencies in a database,it is a good idea to create a dependency graph.
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37
The design produced by reverse engineering may be described as a table-relationship diagram.
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38
Even if an organization has a very large database,it will be possible to make a complete backup copy of the operational database prior to making structural changes.
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39
The data model produced by reverse engineering is a true conceptual schema.
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40
The EXISTS keyword will be true if any row in the subquery meets the condition.
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41
To drop a foreign key column from a table,no preliminary steps are needed and we can simply use the ALTER TABLE DROP COLUMN statement.
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42
To drop a constraint,no preliminary steps are needed and we can simply use the ALTER TABLE DROP CONSTRAINT statement.
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43
Deleting tables and relationships is basically a matter of dropping foreign key constraints and then dropping the tables.
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44
To drop a nonkey column from a table,no preliminary steps are needed and we can simply use the ALTER TABLE DROP COLUMN statement.
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45
In the database redesign process,before proceeding with the redesign it is often useful to ________.

A)check whether certain conditions or assumptions about the data are valid
B)find out why the design was not done properly the first time
C)stop information systems and users from influencing each other
D)set standards for user behavior
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46
Adding new tables and relationships to a database is difficult.
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47
To drop a primary key column from a table the primary key constraint must first be dropped,but this does not require that related foreign keys based on the column be dropped.
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48
Depending on the DBMS,when changing the minimum cardinality on the parent side from zero to one,the foreign key constraint that defines the relationship may have to be dropped before the change is made and re-added afterwards.
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49
Converting date,money,or other more specific data types to char or varchar will usually succeed.
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50
There are several difficulties with increasing cardinalities from 1:1 to 1:N,one of which is preserving the existing relationships.
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51
Database redesign is fairly easy when ________.

A)information systems and organizations influence each other
B)the design was done correctly the first time
C)there is no data in the database
D)good backups of the database are available
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52
When increasing cardinalities from 1:N to N:M,we basically create a new intersection table,fill it with data and drop the old foreign key.
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53
Which of the following is not a possible step in the database redesign process?

A)Checking whether certain conditions or assumptions about the data are valid
B)Reverse engineering the data model
C)Revising user account name policies
D)Maintaining backups of the existing database
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54
In the database redesign process,an SQL tool that is useful for testing whether or not certain conditions or assumptions are valid is ________.

A)UPDATE
B)DROP TABLE
C)CREATE TRIGGER
D)NOT EXISTS
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55
When decreasing maximum cardinalities,there will always be data loss.
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56
In a correlated subquery of a database that has tables TableOne and TableTwo,if table TableOne is used in the upper SELECT statement,then which table is used in the lower SELECT statement?

A)TableOne
B)TableTwo
C)Both TableOne and TableTwo
D)Either TableOne or TableTwo
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57
To add a NULL column to a table,we simply use the MODIFY TABLE statement.
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58
If a DEFAULT constraint is included when a new column is added to a table,the default value is only applied to new rows and not to the existing rows at the time the new column is added.
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59
To change the minimum cardinality on the parent side from zero to one,the foreign key,which would have been NULL,must be changed to NOT NULL.
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60
To add a NOT NULL column to a table,we first add a NULL column,then we insert values into every row,and finally we change the NULL constraint to NOT NULL.
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61
In a doubly nested set of NOT EXISTS SELECT statements,________.

A)if a row does not not match any row,then it matches every row
B)if a row matches any row,then it matches every row
C)if a row does not match any row,then it does not match every row
D)if a row matches any row,then it does not match every row
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62
The data model produced by reverse engineering is a(n)________.

A)conceptual schema
B)internal schema
C)dependency graph
D)table-relationship diagram
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63
A doubly nested set of NOT EXISTS SELECT statements is ________.

A)a famous pattern in SQL
B)regularly used
C)rarely used to nonexistent in the real world
D)Both A and B are correct
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64
When running an SQL query that uses EXISTS,the EXISTS keyword will be true if ________.

A)any row in the subquery meets the condition
B)all rows in the subquery meet the condition
C)no row in the subquery meets the condition
D)any row in the subquery fails to meet the condition
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65
To add a NULL column to a table,we ________.

A)use the REVISE TABLE command
B)use the ALTER TABLE command
C)use the MODIFY TABLE command
D)create a new table with the NULL column,move the other data,and drop the old table
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66
If a DEFAULT constraint is included when a new column is added to a table,the default value is applied to ________.

A)all existing rows at the time the column is added
B)all new rows
C)all new rows but only after the UPDATE command is issued
D)Both A and B are correct
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67
When running a correlated subquery,the DBMS ________.

A)runs the lower SELECT statement by itself and then sends the results to the upper SELECT statement.
B)runs the upper SELECT statement by itself and then sends the results to the lower SELECT statement.
C)alternates running the lower SELECT statement with running the upper SELECT statement based on each result of the lower SELECT statement
D)Either A or B may be used depending on the query.
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68
In order to make sure the database redesign is working properly during the redesign testing process,a means must be created to ________.

A)reverse engineer all test databases
B)graph dependencies in all test databases
C)recover all test databases to their original state
D)re-interview all relevant users
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69
The data model produced by reverse engineering is not truly a logical model because it will contain ________.

A)tables for strong entities
B)supertype/subtype tables
C)tables for ID-dependent entities
D)intersection tables
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70
In the SQL statements SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1;
The "C1" is called a(n)________.

A)term
B)alias
C)convention
D)label
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71
A dependency graph should include all of the following except ________.

A)tables
B)views
C)triggers
D)DEFAULT values
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72
Which of the following different copies of the database schema is typically not used in the database redesign process?

A)Small test database
B)Data warehouse database
C)Operational database
D)Large test database
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73
When running a correlated subquery,the DBMS always uses ________.

A)regular processing
B)nested processing
C)"quick and dirty" processing
D)SQL-92 processing
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74
The process of reading an actual database schema and producing a data model from that schema is called ________.

A)data modeling
B)data engineering
C)reverse engineering
D)schema modeling
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75
Which of the following SQL statements is a correctly stated correlated subquery?

A)SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1
WHERE C1.SalesRepNo IN
(SELECT S1.SalesRepNo
FROM SALESREP S1
WHERE S1.RepName = 'Smith');
B)SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1
WHERE C1.SalesRepNo IN
(SELECT S1.SaleRepNo
FROM SALESREP S1
WHERE S1.RepName = 'Smith')
AND C1.SalesRepNo=S1.SalesRepNo);
C)SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1
WHERE C1.SalesRepNo IN
(SELECT S1.SaleRepNo
FROM SALESREP S1
WHERE S1.RepName = 'Smith')
AND C1.SalesRepNo<>S1.SalesRepNo);
D)SELECT C1.CustName,C1.SalesRepNo
FROM CUSTOMER C1
WHERE C1.SalesRepNo IN
(SELECT C2.SaleRepNo
FROM CUSTOMER C2
WHERE C1.SalesRepNo=C2.SalesRepNo);
AND C1.OrderNo<>C2.OrderNo);
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76
SQL queries that use EXISTS and NOT EXISTS are ________.

A)normal subqueries
B)correlated subqueries
C)uncorrelated subqueries
D)constraint dependent subqueries
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77
Because of the need to know the functional dependencies in a database,it is a good idea to create a(n)________.

A)conceptual schema
B)internal schema
C)dependency graph
D)table-relationship diagram
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78
To change a table name,we ________.

A)use the SQL RENAME TABLE command
B)use the SQL ALTER TABLENAME command
C)use the SQL MODIFY TABLENAME command
D)create a new table,move the data,and drop the old table
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79
When making any change to the database structure,we may need to check for effects of the change on any of the following except ________.

A)data
B)foreign keys
C)ad-hoc SQL queries
D)triggers
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80
When running an SQL query that uses NOT EXISTS,the NOT EXISTS keyword will be true if ________.

A)any row in the subquery meets the condition
B)all rows in the subquery meet the condition
C)no row in the subquery meets the condition
D)any row in the subquery fails to meet the condition
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