Solved MCQ on Distributed Transaction Management set-1

1) If the transaction is rolled back, all the database changes made inside the transaction are ......

A. made permanent

B. made temporary

C. copied to the log

D. undone

2) Which of the following is not a property of transactions?

A. Atomicity

B. Concurrency

C. Isolation

D. Durability

3) A ......... ensures that transactions are performed as expected.

A. transaction processing monitor

B. transaction procedure monitor

C. isolation monitor

D. transaction log

4) A transaction that completes its execution successfully is said to be .......

A. committed

B. rolled back

C. partially committed

D. Aborted

5) ........ means that a transaction must execute exactly once completely or not at all.

A. durability

B. consistency

C. atomicity

D. isolation

6) Assume transaction A holds a shared lock R. If transaction B also requests for a shared lock on R.

A. It will result in a deadlock situation

B. It will immediately be rejected

C. It will immediately be granted

D. It will be granted as soon as it is released by A

7) ........... means that when it ends, a transaction must leave the database in a consistent state.

A. Data isolation

B. Data duration

C. Data consistency

D. Data non-reputability

8) The number of transactions executed in a given amount of time is called .........

A. utilization

B. execution rate

c. throughput

D. atomicity

9) Isolation means ......

A. transaction must not interfere with each other

B. transaction must interfere with each other

C. transaction must be in consistent state

D. transaction must be executed immediately

10) Which of the following ensures the atomicity of the transaction?

A. Transaction management component of DBMS

B. Application Programmer

C. Concurrency control component of DBMS

D. Recovery management component of DBMS

11) ........ means that a transaction must make its changes permanent to the database ends.

A. isolation

B. locking

C. durability

D. consistency

12) Throughput means

A. number of transactions that are committed in one hour

B. number of operations in a transaction

C. number of transaction that can be aborted in a given amount of time

D. number of transaction that can be executed in a given amount of time

13) ........ deals with individual transactions.

A. isolate transactions

B. transaction recovery

C. system recovery

D. media recovery

14) The part of a database management system which ensures that the data remains in a consistent state is

A. authorization and integrity manager

B. buffer manager

C. transaction manager

D. file manager

15) ......... protocol is used to perform multiple transactions that execute on different database.

A. commit

B. two phase lock

C. two phase commit

D. locking

16) A transaction can do read and write operation on a data item when it acquires ......

A. read mode

B. exclusive mode

C. shared mode

D. write mode

17) In .......... one transaction overwrites the changes of another transaction.

A. uncommitted read problem

B. lost update problem

C. update lost problem

D. dirty read problem

18) Isolation of the transactions is ensured by

A. Transaction management

B. Application programmer

C. Concurrency control

D. Recovery management

19) In dirty read problem .......

A. one transaction reads an uncommitted value of another transaction

B. one transaction reads the committed value for another transaction

C. one transaction reads another transaction

D. one transaction commits another transaction.

20) A transaction can do only read operation and not write operation on a data item when it acquires ....... lock.

A. read mode

B. exclusive mode

C. shared mode

D. write mode

Answers:

1) D. undone

2) B. Concurrency

3) A. transaction processing monitor

4) A. committed

5) C. atomicity

6) C. It will immediately be granted 

7) C. Data consistency

8) c. throughput

9) A. transaction must not interfere with each other

10) A. Transaction management component of DBMS

11) C. durability

12) D. number of transaction that can be executed in a given amount of time

13) B. transaction recovery

14) C. transaction manager

15) C. two phase commit

16) B. exclusive mode

17) B. lost update problem 

18) C. Concurrency control

19) A. one transaction reads an uncommitted value of another transaction

20) C. shared mode

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Solved MCQ on Fundamental of DBMS set-10

1) Which of the following is not a characteristic of a relational database model?

A. Table

B. Tree like structure

C. Complex logical relationship

D. Records

2) Field is otherwise called as ......... of the record

A. data item

B. data type

C. value

D. variable

3) A table can have only one

A. Secondary key

B. Alternate key

C. Unique key

D. Primary key

4) A field can be called as ........... in relation context.

A. random file

B. direct file

C. attribute

D. tuple

5) In the relational modes, cardinality is termed as

A. Number of tuples

B. Number of attributes

C. Number of tables

D. Number of constraints

6) The ........ is used for creating and destroying table, indexes and other forms of structures.

A. data manipulation language

B. data control language

C. transaction control language

D. data definition language

7) The view of total database content is

A. Conceptual view

B. Internal view

C. External view

D. Physical view

8) The ............ refers to the way data is organized in and accessible from DBMS.

A. database hierarchy

B. data organization

C. data sharing

D. data model

9) Architecture of the database can be viewed as

A. two levels

B. four levels

C. three levels

D. one level

10) ........ introduced the relational database rules.

A. Atul kahate

B. James Gossling

C. EF Codd

D. Dennies Rithchie

11) In a relational model, relations are termed as

A. Tuples

B. Attributes

C. Tables

D. Rows

12) When the values in one or more attributes being used as a foreign key must exist in another set of one or more attributes in another table, we have created a(n) ........

A. transitive dependency

B. insertion anomaly

C. referential integrity constraint

D. normal form

13) In the architecture of a database system external level is the

A. physical level

B. logical level

C. conceptual level

D. view level

14) A functional dependency is a relationship between or among .......

A. tables

B. rows

C. relations

D. attributes

15) Related fields in a database are grouped to form a

A. data file

B. data record

C. menu

D. bank

16) .......... is, a table have more than one set of attributes that could be chosen as the key

A. foreign key

B. integrity key

C. relationship

D. candidate key

17) The database environment has all of the following components except.

A. users

B. separate files

C. database

D. database administrator

18) The operation of eliminating columns in a table done by ........ operation.

A. Restrict

B. Project

C. Union

D. Divide

19) The way a particular application views the data from the database that the application uses is a

A. module

B. relational model

C. schema

D. sub schema

20) ....... is a condition specified on a database schema and restricts the data that can be stored in an instance of the database.

A. Key Constraint

B. Check Constraint

C. Foreign key constraint

D. integrity constraint

Answers:

1) B. Tree like structure

2) A. data item

3) D. Primary key

4) C. attribute

5) A. Number of tuples

6) D. data definition language

7) A. Conceptual view

8) D. data model

9) C. three levels

10) C. EF Codd

11) C. Tables

12) C. referential integrity constraint

13) D. view level

14) D. attributes

15) B. data record

16) D. candidate key

17) A. users

18) B. Project

19) D. sub schema

20) B. Check Constraint

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Solved MCQ Questions on Structured Query Language set-6

1) ......keyword is used to eliminate the duplicates.

A. distinct

B. unique

C. union

D. intersect


2) ..........is a query that has another query embedded within it.

A. sub query

B. structured query

C. nested query

D. sequence query


3) Which of the following is not an aggregate operator?

A. MAX

B. MIN

C. TOTAL

D. AVG


4) Any SQL statement inside an embedded SQL program must be inside the boundaries of ....

A. EXE SQL and END

B. EXEC SQL and END

C. EXEC and END-EXEC

D. EXEC SQL and END-EXEC


5) In embedded SQL, the per-compiler translates the SQL statements inside the code blocks into the appropriate ....

A. PL/SQL block

B. SQL * plus

C. 3GL statements

D. equivalent C code blocks


6) ........ accepts multiple rows a SQL query, stores them and hands over them one by one to the 3GL program.

A. database program

B. database cursor

C. database object

D. database constraints


7) The ........... is useful in the case of online application.

A. embedded SQL

B. PL/SQL

C. static SQL

D. dynamic SQL


8) What is the Role of revoke command?

A. To give privilege

B. To get back privilege

C. To execute the query

D. To run the program


9) The clause ALTER TABLE in SQL can be used to

A. add an attribute

B. delete an attribute

C. alter the default values of an attribute

D. all of the above


10) Which of the following operations need the participating relations to be union compatible?

A. UNION

B. INTERSECTION

C. DIFFERENCE

D. All of the above



11) ........ is a virtual table that draws its data from the result of an SQL SELECT statement.

A. View

B. Synonym

C. Sequence

D. Transaction


12) In SQL, which of the following is not a data definition language commands?

A. RENAME

B. REVOKE

C. GRANT

D. UPDATE


13) In SQL, which command(s) is(are) used to change a table's storage characteristics?

A. ALTER TABLE

B. MODIFY TABLE

C. CHANGE TABLE

D. All of the above


14) Which command will delete all data from a table and will not write to the rollback segment?

A. DROP

B. DELETE

C. CASCADE

D. TRUNCATE


15) Which is not part of the Data Definition Language?

A. CREATE

B. ALTER

C. ALTER SESSION

D. CREATE SESSION


16) What operator tests column for the adsence of data?

A. IS Null operator

B. ASSIGNMENT operator

C. LIKE operator

D. NOT operator


17) NOT BETWEEN 10 AND 20 ......

A. displays NULL values

B. does not display NULL values

C. may display NULL values

D. display values


18) Which of the following SQL commands can be used to add data to a database table?

A. ADD

B. UPDATE

C. APPEND

D. INSERT


19) ........ can be used to retrieve data from multiple table.

A. Embedded SQL

B. Dynamic SQL

C. Joins

D. Views


20) .......... privides option for entering SQL queries at execution time, rather than at the development stage.

A. PL/SQL

B. SQL * Plus

C. SQL

D. Dynamic SQL

Answers:

1) A. distinct
2) C. nested query
3) C.TOTAL
4) D. EXEC SQL and END-EXEC
5) C. 3GL statements
6) B. database cursor
7) D. dynamic SQL
8) B. To get back privilege
9) D. all of the above
10) D. All of the above
11) A. View
12) D. UPDATE
13) A. ALTER TABLE
14) B. DELETE
15) C. ALTER SESSION
16) A. IS Null operator
17) B. does not display NULL values
18) D. INSERT
19) C. Joins
20) D. Dynamic SQL

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MCQ on Database Design with Answer set-1

1) What is a data integrity?

A. It is the data contained in database that is non redundant.

B. It is the data contained in database that is accurate and consistent.

C. It is the data contained in database that is secured.

D. It is the data contained in database that is shared.


2) As per equivalence rules for query transformation, selection operation distributes over

A. Union

B. Intersection

C. Set difference

D. All of the above


3) In SQL the word 'natural' can be used with

A. inner join

B. full outer join

C. right outer join

D. all of the above


4) Which of the following relational algebraic operations is not from set theory?

A. Union

B. Intersection

C. Cartesian Product

D. Select


5) An entity set that does not have sufficient attributes to form a primary key is a

A. strong entity set

B. weak entity set

C. simple entity set

D. primary entity set


6) In case of entity integrity, the primary key may be

A. not Null

B. Null

C. both Null and not Null

D. any value


7) A logical schema

A. is the entire database.

B. is a standard way of organizing information into accessible parts.

C. describes how data is actually stored on disk

D. both A and C


8) Which of the operations constitute a basic set of operations for manipulating relational data?

A. Predicate calculus

B. Relational calculus

C. Relational algebra

D. None of the above


9) Which of the following is another name for weak entity?

A. Child

B. Owner

C. Dominant

D. All of the above


10) Which of the following is record based logical model?

A. Network Model

B. Object oriented model

C. E-R model

D. None of the above



11) A file manipulation command that extracts some of the records from a file is called

A. SELECT

B. PROJECT

C. JOIN

D. PRODUCT


12) In E-R Diagram derived attribute are represented by

A. Ellipse

B. Dashed ellipse

C. Rectangle

D. Triangle


13) The natural join is equal to

A. Cartesian Product

B. Combination of Union and Cartesian product

C. Combination of selection and Cartesian product

D. Combination of projection and Cartesian product


14) In E-R diagram relationship type is represented by

A. Ellipse

B. Dashed ellipse

C. Rectangle

D. Diamond


15) In E-R diagram generalization is represented by

A. Ellipse

B. Dashed ellipse

C. Rectangle

D. Triangle


16) A table joined with itself is called

A. Join

B. Self Join

C. Outer Join

D. Equi Join


17) ........... means multiple copies of the same data items.

A. Data reduction

B. Data integrity

C. Data consistency

D. Data redundancy


18) Different values for the same data item is referred to as .......

A. data consistency

B. data inconsistency

C. data integrity

D. data duplication


19) The .......... returns row after combining two tables based on common values.

A. difference

B. product

C. join

D. union


20) The .......... can be used to ensure database integrity.

A. entity integrity

B. database constraints

C. referential integrity

D. cardinality

Answers:

1) B. It is the data contained in database that is accurate and consistent.
2) All of the above
3) A. inner join
4) D. Select
5) B. weak entity set
6) A. not Null
7) A. is the entire database.
8) C. Relational algebra
9) Child
10) A. Network Model
11) A. SELECT
12) B. Dashed ellipse
13) D. Combination of projection and Cartesian product
14) D. Diamond
15) D. Triangle
16) B. Self Join
17) D. Data redundancy
18) B. data inconsistency
19) C. join
20) B. database constraints

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Objective Questions on Relational Algebra with Answer set-1

1. Which of the following relational algebra operations do not require the participating tables to be union-compatible?

A. Union

B. Intersection

C. Difference

D. Join


2) Relational Algebra does not have

A. Selection operator

B. Projection operator

C. Aggregation operator

D. Division operator


3) Tree structures are used to store data in

A. Network model

B. Relational model

C. Hierarchical model

D. File based system


4) The rule that a value of a foreign key must appear as a value of some specific table is called a

A. Referential constraint

B. Index

C. Integrity constraint

D. Functional dependency


5) It is an abstraction through which relationships are treated as higher level entities.

A. Generalization

B. Specialization

C. Aggregation

D. Inheritance


6) The operation which is not considered a basic operation of relational algebra is

A. Join

B. Selection

C. Union

D. Cross product


7) In SQL the statement select*from R,S is equivalent to

A. Select * from R natural join S

B. Select * from R cross join S

C. Select * from R union join S

D. Select * from R inner join S


8) When an E-R diagram is mapped to tables, the representation is redundant for

A. Weak entity sets

B. weak relationship sets

C. Strong entity sets

D. strong relationship sets


9) If two relations R and S are joined, then the non matching ruples of both R and S are ignored in

A. left outer join

B. right outer join

C. full outer join

D. inner join


10) Relational Algebra is

A. Data Definition Language

B. Meta Language

C. Procedural query Language

D. None of the above



11) If an entity can belong to only one lower level entity then the constraint is

A. disjoint

B. partial

C. overlapping

D. single


12) The common column is eliminated in

A. theta join

B. outer join

C. natural join

D. composed join


13) In E-R diagram total participation is represented by

A. double lines

B. Dashed lines

C. single line

D. Triangle


14) Relationships among relationships can be represented in an E-R model using

A. Aggregation

B. Association

C. Weak entity sets

D. Weak relationship sets


15) Which of the following constitutes a basic set of operations for manipulating relational data?

A. Predicate calculus

B. Relational calculus

C. Relational algebra

D. SQL


16) Relational calculus is a

A. Procedural language

B. Non-Procedural language

C. Data definition language

D. High level language


17) Cartesian product in relational algebra is

A. a Unary operator

B. a Binary operator

C. a Ternary operator

D. not defined



18) In an E-R diagram attributes are represented by

A. rectangle

B. square

C. ellipse

D. triangle



19) In an E-R diagram an entity set is represent by a

A. rectangle

B. ellipse

C. diamond box

D. circle



20) E-R model uses this symbol to represent weak entity set?

A. Dotted rectangle

B. Diamond

C. Doubly outlined rectangle

D. None of these

Answers:

1) D.Join

2) C. Aggregation operator

3) C. Hierarchical model

4) A. Referential constraint

5) C. Aggregation

6) A. Join

7) B. Select * from R cross join S

8) B. weak relationship sets

9) D. inner join

10) C. Procedural query Language

11) B. partial

12) C. natural join

13) A. double lines

14) A. Aggregation

15) C. Relational algebra

16) B. Non-Procedural language

17) B. a Binary operator

18) C. ellipse

19) A. rectangle

20) C. Doubly outlined rectangle

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Solved Objective Questions on SQL and Embedded SQL set-5

1) DROP is a ................ statement in SQL.

A. Query

B. Embedded SQL

C. DDL

D. DCL


2) The keyword to eliminate duplicate rows from the query result in SQL is.

A. DISTINCT

B. NO DUPLICATE

C. UNIQUE

D. None of the above


3) Which of the following aggregate function does not ignore nulls in its results?

A. COUNT

B. COUNT(*)

C. MAX

D. MIN


4) In SQL, testing whether a subquery is empty is done using

A. DISTINCT

B. UNIQUE

C. NULL

D. EXISTS


5) ................ operator is used to compare a value to a list of literals values that have been specified.

A. Like

B. Compare

C. Between

D. In


6) The language used in application programs to request data from the DBMS is referred to as the

A. DML

B. DDL

C. VDL

D. SDL


7) The DBMS language component which can be embedded in a program is

A. The data definition language(DDL)

B. The data manipulation language(DML)

C. The database administrator(DBA)

D. A query language


8) A DBMS query language is designed to

A. Support end users who use English-like commands.

B. Support in the development of complex applications software.

C. Specify the structure of a database.

D. All of the above


9) It is possible to define a schema completely using.

A. VDL and DDL

B. DDL and DML

C. SDL and DDL

D. VDL and DML


10) Which of the following is correct.

A. a SQL query automatically eliminates duplicates.

B. SQL permits attribute names to be repeated in the same relation.

C. a SQL query will not work if there are no indexes on the relations.

D. None of these.



11) Which of the following is a comparison operator in SQL?

A. =

B. LIKE

C. BETWEEN

D. All of the above


12) To delete a particular column in a relation the command used is.

A. UPDATE

B. DROP

C. ALTER

D. DELETE


13) The ............ operator is used to compare the value to a list of literals values that that have been specified.

A. BETWEEN

B. ANY

C) IN

D) ALL


14) ............ function divides one numeric expression by another and returns the remainder.

A. POWER

B. MOD

C. ROUND

D. REMAINDER


15) A data manipulation command the combines the record from one or more tables is called.

A) SELECT

B. PROJECT

C. JOIN

D. PRODUCT


16) DDL stands for

A. Data definition language

B. Data description language

C. Data design languages

D. Database dictionary languages.


17) The DDL is used to specify the ........

A. Conceptual schema

B. Internal schema

C. Both

D. None


18) Which is used for data retrieval from the database?

A. DDL

B. DML

C. SDL

D. VDL


19) Which is used to specify the user views and their mappings to the conceptual schema?

A. DDL

B. DML

C. SDL

D. VDL


20) Which command are included in a general purpose programming languages?

A. DDL

B. DML

C. DSL

D. VDL

Answers:

1) C. DDL

2) C. UNIQUE

3) B. COUNT(*)

4) D. EXISTS

5) A. Like

6) A. DML

7) B. The data manipulation language(DML)

8) D. All of the above

9) B. DDL and DML

10) D. None of these.

11) D. All of the above

12) C. ALTER

13) A. BETWEEN

14) B. MOD

15) C. JOIN

16) A. Data definition language

17) A.Conceptual schema

18) B.DML

19) D.VDL

20) B.DML

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How to Load External JavaScript Asynchronously or Dynamically

JavaScript makes more easier to manipulate websites, now a days most of the browsers supporting JavaScript codes. When the HTML parser encounters a <script> element, by default, run the script before it can parsing and rendering the document. It is not much problem for inline scripts but if the script source code is in an external file specified with a src attribute, the portions of the document that follow the Script will not appear in the browser until the script has been downloaded and executed.This makes loading of the website much slower, which makes bad user experience for your website and may not also indexing of your website by the search engines.


This Synchronous or blocking script execution is the default only. The <script> tag can have defer and async attributes, which cause scripts to be executed differently. This makes your website loading much faster than before and appears contents of your site by loading at first.

Loading JavaScript Asynchronously using async or defer attributes

Both the defer and acync attributes are ways of telling the browser that the linked script does not use document.write() and won't be generating document content, and that therefore the browser can continue to parse and render the document while downloading the script. You can use async or defer attributes as the following.

<script defer src="deferred.js"></script> 
<script async src="async.js"></script>

The defer attribute causes the browser to defer execution of the script until after the document has been loaded and parsed and is ready to be manipulated. The async attribute causes the browser to run the script as soon as possible but not to block document parsing while the script is being downloaded. If a <script> tag has both attributes, a browser that supports both will honor the async attribute and ignore the defer attribute. Deferred scripts run in the order in which they appear in the document, while acync scripts run as they load, which means that they may execute out of order.

Here is an example of acync script uses in this blog for Intensedebate comments script source.

<script async='async' expr:src='data:post.commentSrc' type='text/javascript'/>

Loading JavaScript Asynchronously by loading scripts dynamically

You can load and execute scripts asynchronously, even in browsers that do not support the async attribute, by dynamically creating a <script> element and inserting it into the document. Here is an example how to load scripts dynamically.

function loadasync(url){
var head=document.getElementByTagName("head")[0]; 
var s=document.createElement("script"); 
s.src=url;
head.appendchild(s);
}

This loadsaync() function finds the <head> tag and attach <script> tag below opening of head tag and loads scripts dynamically. Scripts that are neither included inline within the web page or referenced statically from the web page are loaded into the document and become part of the running JavaScript program.

You can use the following method to execute loadsync() function, when document finished loading.

function loadasync(){ ..................}
request.onreadystatechange=loadasync;

Here is an example of loading JavaScript asynchronously by loading scripts dynamically used in this blog for external scripts from infolinks ads.

<div style='display:none'>  <div id='adsource-0'>
<script type='text/javascript'>
var infolinks_pid = 9993182;
var infolinks_wsid = 1;
</script>
    <script language='javascript' src='http://resources.infolinks.com/js/infolinks_main.js' type='text/javascript'/>
  </div>
</div>
<script type='text/javascript'>
    source = document.getElementById("adsource-0");
    placeholder = document.getElementById("ad-0");
    placeholder.appendChild(source);
</script>

I have placed this code at the bottom of HTML codes, i.e. just before </body> tag and have placed the following code where I want to display ads.

<div id="ad-0" align="center"></div>

Loading JavaScript Asynchronously when document finishes loading 

You can load and execute scripts asynchronously by using setTimeout(), addEventListner(), and attachEvent(). Most objects that can be event targets have a method named addEventListner(), which allows the registration of multiple listeners.

window.addEventListner("load", function(){.....},false);
request.addEventListner("readystatechange", function(){......},false);

The first argument to this function is the name of the event. For IE8 and earlier, you must use a similar method, named attachEvent().

window.attachevent("onload", function() {.....});

Here is an example which define an onLoad() function that registers a function to be run when the document finishes loading. If the document has already loaded, run it asynchronously.

function onLoad(f){
if(onLoad.loaded) 
 window.setTimeout(f,0); 
elseif (window.addEventListner)
 window.addEventListner("load",f,false);
elseif (window.attachEvent)
 window.attachEvent("onload",f);
}

onLoad.loaded=false;

onLoad(function(){onLoad.loaded=true;});

In the above script window.attachEvent is used for IE8 and earlier. onLoad.loaded=false; sets a flag that indicates the document is not loaded yet and onLoad(function(){onLoad.loaded=true;}); register a function to set the flag when the document does load.

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