Recent questions tagged databases / GATE Overflow for GATE CSE

0 votes

0 answers

871

applied course
How to convert above E-R diagram to Relations? Sorry for adding image instead of typing..

How to convert above E-R diagram to Relations?Sorry for adding image instead of typing..

screddy1313

571 views

screddy1313 asked Jan 27, 2019

0 votes

1 answer

872

Relational algebra and SQL
SQL Aggregation is possible by extended relational algebra operators? SQL grouping is possible in relational algebra. Relational algebra is equivalent to safe relational calculus expressions, then grouping and aggregation possible in tuple relational calculus ... calculus? What about ordering? Please explain how will we consider these questions from GATE point of view.

SQL Aggregation is possible by extended relational algebra operators? SQL grouping is possible in relational algebra. Relational algebra is equivalent to safe relational ...

Aman Janko

844 views

Aman Janko asked Jan 27, 2019

4 votes

0 answers

873

MadeEasy Full Length Test 2019: Databases - Er Diagram
Find minimum number of tables needed? Answer : (3) Can anyone please explain the answer and how to approach such complex er diagrams?

Find minimum number of tables needed?Answer : (3)Can anyone please explain the answer and how to approach such complex er diagrams?

vk_9_1_9

896 views

vk_9_1_9 asked Jan 26, 2019

3 votes

1 answer

874

Ace Test Series: DBMS - File Indexing

Na462

1.9k views

Na462 asked Jan 26, 2019

0 votes

2 answers

875

Virtual Gate Test Series: Databases - Schedule
Which of the following is/are true? I. Every strict schedule is cascade less schedule and recoverable schedule II. Every cascade less schedule is recoverable schedule III. Every cascading rollback schedule is recoverable schedule IV. Every cascading rollback schedule is a ... of the above I, II, and IV only II, III, IV, and V only I, II, and III only

Which of the following is/are true?I. Every strict schedule is cascade less schedule and recoverable scheduleII. Every cascade less schedule is recoverable scheduleIII. E...

jatin khachane 1

1.6k views

jatin khachane 1 asked Jan 26, 2019

1 votes

1 answer

876

MadeEasy Workbook: Databases - Database Normalization
Find the highest normal form. AB - - > CE E - - >AB C-->D Doubt AB, E are the candidate key. The answer given is 2NF In 2NF, there should be no partial dependency which is PRIME ATTRIBUTE - - >NON PRIME ATTRIBUTE But it is there in AB-->CE, I think CE is non prime attribute. Or bcoz of E we consider them as prime attribute.

Find the highest normal form.AB - - CEE - - >ABC >DDoubtAB, E are the candidate key.The answer given is 2NFIn 2NF, there should be no partial dependency which isPRIME AT...

Jyoti Kumari97

510 views

Jyoti Kumari97 asked Jan 25, 2019

0 votes

0 answers

877

me adv test
Consider the following schedule: S:R2(A), W1(B), W1(C), R3(B), R2(B), R1 (A), commit_1, R2(C), commit_2, W3(A), commit_3 How many given statements true about schedule(S)____. (i) Schedule(S) is conflict serializable schedule. (ii) Schedule(S) is ... strict recoverable schedule. (iv) Schedule(S) is allowed by strict 2PL. only 1 is correct as per my answer but in answer they have given 3

Consider the following schedule:S:R2(A), W1(B), W1(C), R3(B), R2(B), R1 (A), commit_1, R2(C), commit_2, W3(A), commit_3How many given statements true about schedule(S)___...

newdreamz a1-z0

507 views

newdreamz a1-z0 asked Jan 24, 2019

1 votes

1 answer

878

MadeEasy Workbook: Databases - Database Normalization

Jyoti Kumari97

741 views

Jyoti Kumari97 asked Jan 23, 2019

0 votes

1 answer

879

SELF DOUBT: Korth DBMS, Relational Algebra Union Operation
Question:- a query to find the set of all courses taught in the Fall 2009 semester, the Spring 2010 semester, or both. Table given:- Given Relational Algebra expression:- Doubt:- If I write the relational Algebra expression as this ... then does it gives same output as they had given in terms of union The output is highlighted in image?

Question:- a query to find the set of all courses taught in the Fall 2009 semester, the Spring 2010 semester, or both. Table given:- Given Relational Algebra expression:-...

kd.....

1.1k views

kd..... asked Jan 23, 2019

0 votes

1 answer

880

indexing
among primary index, secondary index, clustered index which index are dense or sparse or both?

among primary index, secondary index, clustered index which index are dense or sparse or both?

Rahul_Rathod_

835 views

Rahul_Rathod_ asked Jan 22, 2019

0 votes

0 answers

881

Is there any example of schedule which is Strict but not serializable
I have gone through link https://stackoverflow.com/questions/40859477/is-a-strict-schedule-always-serializable But i don’t think example given there is correct.I don’t think it is strict schedule as T2 is reading x which is written by T1 , even before T1 commits. Hence is any other example which is strict but not serializable?

I have gone through link https://stackoverflow.com/questions/40859477/is-a-strict-schedule-always-serializableBut i don’t think example given there is correct.I don’t...

mehul vaidya

326 views

mehul vaidya asked Jan 22, 2019

0 votes

1 answer

882

Self Doubt
Consider the following relation: R (A1, A2, ….An) and every (n-2) attributes of R forms a candidate key. How many super keys are there in R?

Consider the following relation:R (A1, A2, ….An) and every (n-2) attributes of R forms a candidate key. How many superkeys are there in R?

kumar.dilip

1.8k views

kumar.dilip asked Jan 21, 2019

2 votes

1 answer

883

Normal forms
Select the ‘False’ statement from the following statements about Normal Forms: 1. BCNF is stronger than 3NF 2. Lossless preserving decomposition into BCNF is always possible 3. Any Relation with two attributes is in BCNF 4. Lossless preserving decomposition into 3NF is always possible

Select the ‘False’ statement from the following statements about Normal Forms:1. BCNF is stronger than 3NF2. Lossless preserving decomposition into BCNF is always po...

Hardik Vagadia

1.1k views

Hardik Vagadia asked Jan 21, 2019

2 votes

0 answers

884

Ace Test Series: DBMS - Functional Dependency

Na462

903 views

Na462 asked Jan 21, 2019

0 votes

0 answers

885

SQL Insert command
Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) Assume all the following four statements are executed in the same sequence order. S1: INSERT INTO employees (employee_id) VALUES (1000); S2: INSERT INTO ... ? →S2 won't execute as we are trying to make primary key value as NuLL. But isn't S4 also invalid?

Examine the structure of the EMPLOYEES table:EMPLOYEE_ID NUMBER Primary KeyFIRST_NAME VARCHAR2(25)LAST_NAME VARCHAR2(25)Assume all the following four statements are execu...

Hardik Vagadia

316 views

Hardik Vagadia asked Jan 21, 2019

0 votes

0 answers

886

self doubt - NO. of tables after normalizing
Are 3NF decompostions and BCNF decompostions unique? Are 4NF important for GATE (since I've left them :( ) See, I am asking this question because I want to know whether they'll ask about no. of tables we get after normalizing upto 3nf or bcnf. Now ... I am in a bit hurry to search for that.. so please forgive me if it has been already asked.) Thank you.

Are 3NF decompostions and BCNF decompostions unique? Are 4NF important for GATE (since I’ve left them :( )See, I am asking this question because I want to know whethe...

Harsh Kumar

385 views

Harsh Kumar asked Jan 21, 2019

1 votes

1 answer

887

GATE 1997-2.7 Small change in given data
Consider the schema R = (S T U V) and the dependencies S → T, T → U, U → V and V → S. Let R = (R1 and R2) be a decomposition such that R1 ∩ R2 = ϕ. (In the actual gate question it was R1∩R2 ≠ ϕ) The decomposition is:- not in 2NF in 2NF but not 3NF in 3NF but not in 2NF in both 2NF and 3NF

Consider the schema R = (S T U V) and the dependencies S → T, T → U, U → V and V → S. Let R = (R1 and R2) be a decomposition such that R1 ∩ R2 = ϕ. (In the act...

Sukhbir Singh

1.2k views

Sukhbir Singh asked Jan 21, 2019

0 votes

1 answer

888

made easy test series

Himanshu Kashyap

452 views

Himanshu Kashyap asked Jan 21, 2019

0 votes

0 answers

889

Self doubt
IS nested loop join concept is there in gate? these questions came in gate 2005 and 2014 please tell me https://gateoverflow.in/3847/gate2005-it-82a https://gateoverflow.in/1989/gate2014-2-30

IS nested loop join concept is there in gate?these questions came in gate 2005 and 2014 please tell mehttps://gateoverflow.in/3847/gate2005-it-82a https://gateoverflow.in...

Prince Sindhiya

282 views

Prince Sindhiya asked Jan 20, 2019

0 votes

0 answers

890

made easy test series
Employee(Eid, Ename , salary) find Eid of employee(s) who make the highest salary. answer given is {E1.Eid | E1 ∈ Employee ^ ¬ ( ∃ E2 ∈ Employee ( E2.salary > E1.salary ))} please explain how query is returning correct value.

Employee(Eid, Ename , salary)find Eid of employee(s) who make the highest salary.answer given is{E1.Eid | E1 ∈ Employee ^ ¬ ( ∃ E2 ∈ Employee ( E2.salary E1.sala...

Satbir

527 views

Satbir asked Jan 20, 2019

0 votes

1 answer

891

MadeEasy Test Series 2019: Databases - Database Normalization
A3 also deriving {A1,A2,A3} from FD’s...why it is still neglecting BCNF? Is solution wrong or I am misunderstanding?

A3 also deriving {A1,A2,A3} from FD’s...why it is still neglecting BCNF? Is solution wrong or I am misunderstanding?

Naveen Muralidhar

546 views

Naveen Muralidhar asked Jan 20, 2019

1 votes

0 answers

892

self_doubt
I am confused about indexing being densed or sparse, Read a lot of answer but can't figure out Primary Index is always sparse : since indexing is done of key attribute and records(files) are ordered so we create index only for anchor of the block(group of records) ... record and is only for some records. Please correct me If I am wrong at some point and If I am right then please comment.

I am confused about indexing being densed or sparse, Read a lot of answer but can’t figure outPrimary Index is always sparse : since indexing is done of key attribute a...

Shivam Kasat

411 views

Shivam Kasat asked Jan 20, 2019

1 votes

1 answer

893

Ace Test Series: DBMS - Multi level indexing

Na462

975 views

Na462 asked Jan 19, 2019

1 votes

1 answer

894

Ace Test Series 2019: DBMS - SQL Output

Na462

1.2k views

Na462 asked Jan 19, 2019

0 votes

0 answers

895

Dbms general doubt
Is repetition allow in foreign key ? Give some reference

Is repetition allow in foreign key ?Give some reference

Prince Sindhiya

348 views

Prince Sindhiya asked Jan 18, 2019

3 votes

4 answers

896

No. of View equivalent schedules
how many view equivalent schedules are possible for the Sch given below:

how many view equivalent schedules are possible for the Sch given below:

Nandkishor3939

2.3k views

Nandkishor3939 asked Jan 18, 2019

3 votes

0 answers

897

MadeEasy Full Length Test 2019: Databases - Er Diagram
Consider the following ER diagram: How many number of relations are required for the above ER diagram? 2 3 5 1 Solution: My doubt is: Since $E_2$ isn't involved in total participation with $E_1$ so on merging we might get 2NF ... 2-NF violation. So by default which case is to be considered when normalization form is not mentioned?? 1-NF?

Consider the following ER diagram:How many number of relations are required for the above ER diagram?2351Solution:My doubt is:Since $E_2$ isn’t involved in total partic...

MiNiPanda

781 views

MiNiPanda asked Jan 18, 2019

0 votes

1 answer

898

Database
minimum no fo relation require for this ER diagram i am thinking 3 relation but given answer is______something else

minimum no fo relation require for this ER diagrami am thinking 3 relation but given answer is______something else

Gurdeep Saini

488 views

Gurdeep Saini asked Jan 18, 2019

2 votes

0 answers

899

Self doubt, 2PL
Is different 2 phase locking a subset of each other? For example, if the schedule is Strict 2PL then it will also be simple 2PL. Something like a 2PL is a subset of Strict 2PL is a subset of rigorous 2PL.

Is different 2 phase locking a subset of each other? For example, if the schedule is Strict 2PL then it will also be simple 2PL.Something like a 2PL is a subset of Strict...

vinay chauhan

600 views

vinay chauhan asked Jan 18, 2019

0 votes

1 answer

900

Confused
In ER-DIAGRAM to Relation conversion : I can't understand how to handle the following points How to deal with one-to-one relationship with any of the entity having total participation in relation? How to deal with One-to-many relationship with an entity ... in the relationship? How to deal with many-to-many relationship with total participation of one or both the entities in relation?

In ER-DIAGRAM to Relation conversion :I can’t understand how to handle the following pointsHow to deal with one-to-one relationship with any of the entity having total ...

Shivam Kasat

632 views

Shivam Kasat asked Jan 17, 2019

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