Anna University DATABASE MANAGEMENT SYSTEMS Two marks for unit 2
The SQL language has several parts:
2. What are the categories of SQL command?
SQL commands are divided in to the following categories:
1. data -definitition language
2. data manipulation language
3. Data Query language
4. data control language
5. data administration statements
6. transaction control statements
3. What are the three classes of SQL expression?
SQL expression consists of three clauses:
Select From where
4. Give the general form of SQL query?
Select A1, A2…………., An
From R1, R2……………, Rm Where P
5. What is the use of rename operation?
Rename operation is used to rename both relations and a attributes.
It uses the as clause, taking the form:
Old-name as new-name
6. Define tuple variable?
Tuple variables are used for comparing two tuples in the same relation. The tuple
variables are defined in the from clause by way of the as clause.
7. List the string operations supported by SQL?
1) Pattern matching Operation
2) Concatenation
3) Extracting character strings
4) Converting between uppercase and lower case letters.
8. List the set operations of SQL?
1)Union
2) Intersect operation
3) The except operation
9. What is the use ofUnion and intersection operation?
Union : The result of this operation includes all tuples that are either in r1 or in r2
or in both r1 and r2.Duplicate tuples are automatically eliminated.
Intersection: The result of this relation includes all tuples that are in both r1 and
r2.
10. What are aggregate functions? And list the aggregate functions supported by
SQL?
Aggregate functions are functions that take a collection of values as input and
return a single value. Aggregate functions supported by SQL are
Average: avg
Minimum: min
Maximum: max
Total: sum
Count: count
11. What is the use of group by clause?
Group by clause is used to apply aggregate functions to a set of tuples.The
attributes given in the group by clause are used to form groups.Tuples with the
same value on all attributes in the group by clause are placed in one group.
12. What is the use of sub queries?
A sub query is a select-from-where expression that is nested with in another
query. A common use of sub queries is to perform tests for set membership, make
setcomparisions, and determine set cardinality.
13. What is view in SQL? How is it defined?
Any relation that is not part of the logical model, but is made visible to a user as a
virtual relation is called a view.
We define view in SQL by using the create view command. The form of the
create view command is
Create view v as <query expression>
14. What is the use of with clause in SQL?
The with clause provides a way of defining a temporary view whose definition is
available only to the query in which the with clause occurs.
15. List the table modification commands in SQL?
Deletion
Insertion
Updates
Update of a view
16. List out the statements associated with a database transaction?
Commit work
Rollback work
17. What is transaction?
Transaction is a unit of program execution that accesses and possibly updated
various data items.
18. List the SQL domain Types?
SQL supports the following domain types.
1) Char(n) 2) varchar(n) 3) int 4) numeric(p,d)
5) float(n) 6) date.
19. What is the use of integrity constraints?
Integrity constraints ensure that changes made to the database by authorized users
do not result in a loss of data consistency. Thus integrity constraints guard against
accidental damage to the database.
20. Mention the 2 forms of integrity constraints in ER model?
Key declarations
Form of a relationship
21. What is trigger?
Triggers are statements that are executed automatically by the system as the side
effect of a modification to the database.
22. What are domain constraints?
A domain is a set of values that may be assigned to an attribute .all values that
appear in a column of a relation must be taken from the same domain.
23. What are referential integrity constraints?
A value that appears in one relation for a given set of attributes also appears for a
certain set of attributes in another relation.
24. What is assertion? Mention the forms available.
An assertion is a predicate expressing a condition that we wish the database
always to satisfy.
Domain integrity constraints.
Referential integrity constraints
25. Give the syntax of assertion?
Create assertion <assertion name>check<predicate>
26. What is the need for triggers?
Triggers are useful mechanisms for alerting humans or for starting certain tasks
automatically when certain conditions are met.
27. List the requirements needed to design a trigger.
The requirements are
Specifying when a trigger is to be executed.
Specify the actions to be taken when the trigger executes.
28. Give the forms of triggers?
The triggering event can be insert or delete.
For updated the trigger can specify columns.
The referencing old row as clause
The referencing new row as clause
The triggers can be initiated before the event or after the event.
29. What does database security refer to?
Database security refers to the protection from unauthorized access and malicious
destruction or alteration.
30. List some security violations (or) name any forms of malicious access.
Unauthorized reading of data
Unauthorized modification of data
Unauthorized destruction of data.
31. List the types of authorization.
Read authorization
Write authorization
Update authorization
Drop authorization
32. What is authorization graph?
Passing of authorization from one user to another can be represented by an
authorization graph.
33. List out various user authorization to modify the database schema.
Index authorization
Resource authorization
Alteration authorization
Drop authorization
34. What are audit trails?
An audit trail is a log of all changes to the database along with information such
as which user performed the change and when the change was performed.
35. Mention the various levels in security measures.
Database system
Operating system
Network
Physical
human
36. Name the various privileges in SQL?
Delete
Select
Insert
update
37. Mention the various user privileges.
All privileges directly granted to the user or role.
All privileges granted to roles that have been granted to the user or role.
38. Give the limitations of SQL authorization.
The code for checking authorization becomes intermixed with the rest of the
application code.
Implementing authorization through application code rather than specifying it
declaratively in SQL makes it hard to ensure the absence of loopholes.
39. Define the term Domain.
For each attribute there is a set of permitted values called the domain of that
attribute.
40. What is a candidate key?
Minimal super keys are called candidate keys.
41. What is a primary key?
Primary key is chosen by the database designer as the principal means of
identifying an entity in the entity set.
42. What is a super key?
A super key is a set of one or more attributes that collectively allows us to
identify uniquely an entity in the entity set.
43. Define-relational algebra.
The relational algebra is a procedural query language. It consists of a set of
operations that take one or two relation as input and produce a new relation as
output.
44. What is a SELECT operation?
The select operation selects tuples that satisfy a given predicate. We use the
lowercase letter sssss to denote selection.
45. What is a PROJECT operation?
The project operation is a unary operation that returns its argument relation with
certain attributes left out. Projection is denoted by pie (p
pppp).
46. Write short notes on domain relational calculus
The domain relational calculus uses domain variables that take on values from an
attribute domain rather than values for entire tuple.
47. Define query language?
A query is a statement requesting the retrieval of information. The portion of
DML that involves information retrieval is called a query language.
48. Give some encryption techniques?
DES
AES
Public key encryption
49. What does authentication refer?
Authentication refers to the task of verifying the identity of a person.
50. List some authentication techniques.
Challenge response scheme
Digital signatures
Nonrepudiation
1.What is meant by term relationship between entities ? Explain the different types of relationships that can exist with examples ?
2.Explain the concept of dependent entities ? give example.
3.What do you mean by mapping cardinalities ? Explain various type of cardinalities.
4.What is difference between total and partial participation ? Explain.
5.What is the difference b/w single and multivalued attributes ? Explain.
6. What do you mean by Null values? Explain with suitable examples.
7.Discuss the various update operation on relation and types of integrity constraints that must be checked for each update operation ?
8. What is relational algebra ? Discuss the various operations of relational algebra.
9. Describe the different types of relational calculus in detail.
10.What dis relational calculus ? Differentiate relational algebra and relational calculus.
11.What do you understand by distributed databases? Give the various advantages and disadvantages of distributed database management system.
12. Explain the architecture of Client-Server databases in detail.
13. What are the main differences between a parallel and a distributed system ? Explain
14. Explain nested Queries with examples
15. Explain embedded SQL in detail
16.Explain the integrity constraints supported by SQL
17.Explain triggers with example.
18.Explain security and authorization and Security in SQL
19.Explain dynamic SQL in detail
20. Explain distributed Database in detail
21. Explain CSDB in detail
PART A
1. What are the parts of SQL language?The SQL language has several parts:
- data -definitition language
- Data manipulation language
- View definition
- Transaction control
- Embedded SQL
- Integrity
- Authorization
2. What are the categories of SQL command?
SQL commands are divided in to the following categories:
1. data -definitition language
2. data manipulation language
3. Data Query language
4. data control language
5. data administration statements
6. transaction control statements
3. What are the three classes of SQL expression?
SQL expression consists of three clauses:
Select From where
4. Give the general form of SQL query?
Select A1, A2…………., An
From R1, R2……………, Rm Where P
5. What is the use of rename operation?
Rename operation is used to rename both relations and a attributes.
It uses the as clause, taking the form:
Old-name as new-name
6. Define tuple variable?
Tuple variables are used for comparing two tuples in the same relation. The tuple
variables are defined in the from clause by way of the as clause.
7. List the string operations supported by SQL?
1) Pattern matching Operation
2) Concatenation
3) Extracting character strings
4) Converting between uppercase and lower case letters.
8. List the set operations of SQL?
1)
2) Intersect operation
3) The except operation
9. What is the use of
or in both r1 and r2.Duplicate tuples are automatically eliminated.
Intersection: The result of this relation includes all tuples that are in both r1 and
r2.
10. What are aggregate functions? And list the aggregate functions supported by
SQL?
Aggregate functions are functions that take a collection of values as input and
return a single value. Aggregate functions supported by SQL are
Average: avg
Minimum: min
Maximum: max
Total: sum
Count: count
11. What is the use of group by clause?
Group by clause is used to apply aggregate functions to a set of tuples.The
attributes given in the group by clause are used to form groups.Tuples with the
same value on all attributes in the group by clause are placed in one group.
12. What is the use of sub queries?
A sub query is a select-from-where expression that is nested with in another
query. A common use of sub queries is to perform tests for set membership, make
setcomparisions, and determine set cardinality.
13. What is view in SQL? How is it defined?
Any relation that is not part of the logical model, but is made visible to a user as a
virtual relation is called a view.
We define view in SQL by using the create view command. The form of the
create view command is
Create view v as <query expression>
14. What is the use of with clause in SQL?
The with clause provides a way of defining a temporary view whose definition is
available only to the query in which the with clause occurs.
15. List the table modification commands in SQL?
Deletion
Insertion
Updates
Update of a view
16. List out the statements associated with a database transaction?
Commit work
Rollback work
17. What is transaction?
Transaction is a unit of program execution that accesses and possibly updated
various data items.
18. List the SQL domain Types?
SQL supports the following domain types.
1) Char(n) 2) varchar(n) 3) int 4) numeric(p,d)
5) float(n) 6) date.
19. What is the use of integrity constraints?
Integrity constraints ensure that changes made to the database by authorized users
do not result in a loss of data consistency. Thus integrity constraints guard against
accidental damage to the database.
20. Mention the 2 forms of integrity constraints in ER model?
Key declarations
Form of a relationship
21. What is trigger?
Triggers are statements that are executed automatically by the system as the side
effect of a modification to the database.
22. What are domain constraints?
A domain is a set of values that may be assigned to an attribute .all values that
appear in a column of a relation must be taken from the same domain.
23. What are referential integrity constraints?
A value that appears in one relation for a given set of attributes also appears for a
certain set of attributes in another relation.
24. What is assertion? Mention the forms available.
An assertion is a predicate expressing a condition that we wish the database
always to satisfy.
Domain integrity constraints.
Referential integrity constraints
25. Give the syntax of assertion?
Create assertion <assertion name>check<predicate>
26. What is the need for triggers?
Triggers are useful mechanisms for alerting humans or for starting certain tasks
automatically when certain conditions are met.
27. List the requirements needed to design a trigger.
The requirements are
Specifying when a trigger is to be executed.
Specify the actions to be taken when the trigger executes.
28. Give the forms of triggers?
The triggering event can be insert or delete.
For updated the trigger can specify columns.
The referencing old row as clause
The referencing new row as clause
The triggers can be initiated before the event or after the event.
29. What does database security refer to?
Database security refers to the protection from unauthorized access and malicious
destruction or alteration.
30. List some security violations (or) name any forms of malicious access.
Unauthorized reading of data
Unauthorized modification of data
Unauthorized destruction of data.
31. List the types of authorization.
Read authorization
Write authorization
Update authorization
Drop authorization
32. What is authorization graph?
Passing of authorization from one user to another can be represented by an
authorization graph.
33. List out various user authorization to modify the database schema.
Index authorization
Resource authorization
Alteration authorization
Drop authorization
34. What are audit trails?
An audit trail is a log of all changes to the database along with information such
as which user performed the change and when the change was performed.
35. Mention the various levels in security measures.
Database system
Operating system
Network
Physical
human
36. Name the various privileges in SQL?
Delete
Select
Insert
update
37. Mention the various user privileges.
All privileges directly granted to the user or role.
All privileges granted to roles that have been granted to the user or role.
38. Give the limitations of SQL authorization.
The code for checking authorization becomes intermixed with the rest of the
application code.
Implementing authorization through application code rather than specifying it
declaratively in SQL makes it hard to ensure the absence of loopholes.
39. Define the term Domain.
For each attribute there is a set of permitted values called the domain of that
attribute.
40. What is a candidate key?
Minimal super keys are called candidate keys.
41. What is a primary key?
Primary key is chosen by the database designer as the principal means of
identifying an entity in the entity set.
42. What is a super key?
A super key is a set of one or more attributes that collectively allows us to
identify uniquely an entity in the entity set.
43. Define-relational algebra.
The relational algebra is a procedural query language. It consists of a set of
operations that take one or two relation as input and produce a new relation as
output.
44. What is a SELECT operation?
The select operation selects tuples that satisfy a given predicate. We use the
lowercase letter sssss to denote selection.
45. What is a PROJECT operation?
The project operation is a unary operation that returns its argument relation with
certain attributes left out. Projection is denoted by pie (p
pppp).
46. Write short notes on domain relational calculus
The domain relational calculus uses domain variables that take on values from an
attribute domain rather than values for entire tuple.
47. Define query language?
A query is a statement requesting the retrieval of information. The portion of
DML that involves information retrieval is called a query language.
48. Give some encryption techniques?
DES
AES
Public key encryption
49. What does authentication refer?
Authentication refers to the task of verifying the identity of a person.
50. List some authentication techniques.
Challenge response scheme
Digital signatures
Nonrepudiation
PART B
1.What is meant by term relationship between entities ? Explain the different types of relationships that can exist with examples ?
2.Explain the concept of dependent entities ? give example.
3.What do you mean by mapping cardinalities ? Explain various type of cardinalities.
4.What is difference between total and partial participation ? Explain.
5.What is the difference b/w single and multivalued attributes ? Explain.
6. What do you mean by Null values? Explain with suitable examples.
7.Discuss the various update operation on relation and types of integrity constraints that must be checked for each update operation ?
8. What is relational algebra ? Discuss the various operations of relational algebra.
9. Describe the different types of relational calculus in detail.
10.What dis relational calculus ? Differentiate relational algebra and relational calculus.
11.What do you understand by distributed databases? Give the various advantages and disadvantages of distributed database management system.
12. Explain the architecture of Client-Server databases in detail.
13. What are the main differences between a parallel and a distributed system ? Explain
14. Explain nested Queries with examples
15. Explain embedded SQL in detail
16.Explain the integrity constraints supported by SQL
17.Explain triggers with example.
18.Explain security and authorization and Security in SQL
19.Explain dynamic SQL in detail
20. Explain distributed Database in detail
21. Explain CSDB in detail
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