Recent questions tagged databases - GATE CSE Doubts

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DBMS_Ace_Quesns
How many clustered indexes a table can have? Any Can’t say Depends on columns in the table none of the above Anyone please clarify.

asked May 2 in Databases by Shivateja MST (124 points) | 7 views

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DBMS Queries 3
A schedule S is having 3 transactions and each transaction is having two different data items and a blind Write A' statement is in all the three transactions. With the above information can you say whether the schedule is serializable ... serial schedules are there serializable and is equivalent to only two serial schedule detailed schedule is needed Anyone please clarify.

asked Apr 29 in Databases by Shivateja MST (124 points) | 17 views

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DBMS Queries
Which of the following statements is false? Every dominant entity is a strong entity. Specialization is done when more than one domain constraint is required on an attribute based on the entity type. A relationship type can be related to another relationship type. A weak entity will not have primary key on its own. Anyone please clarify.

asked Apr 27 in Databases by Shivateja MST (124 points) | 7 views

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GATE2017-2-44 Video Solution
Two transactions $T_1$ and $T_2$ are given as $T_1:r_1(X)w_1(X)r_1(Y)w_1(Y)$ $T_2:r_2(Y)w_2(Y)r_2(Z)w_2(Z)$ where $r_i(V)$ denotes a $\textit{read}$ operation by transaction $T_i$ on a variable $V$ and $w_i(V)$ denotes a ... by transaction $T_i$ on a variable $V$. The total number of conflict serializable schedules that can be formed by $T_1$ and $T_2$ is ______

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2001-2.23 Video Solution
$R(A,B,C,D)$ is a relation. Which of the following does not have a lossless join, dependency preserving $BCNF$ decomposition? $A \rightarrow B, B \rightarrow CD$ $A \rightarrow B, B \rightarrow C, C \rightarrow D$ $ AB \rightarrow C, C \rightarrow AD$ $A \rightarrow BCD$

asked Apr 18 in Databases by admin (3.6k points) | 3 views

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GATE2008-IT-61 Video Solution
Let $R (A, B, C, D)$ be a relational schema with the following functional dependencies : $A → B$, $B → C$, $C → D$ and $D → B$. The decomposition of $R$ into $(A, B), (B, C), (B, D)$ gives a ... a lossless join, but is not dependency preserving does not give a lossless join, but is dependency preserving does not give a lossless join and is not dependency preserving

asked Apr 18 in Databases by admin (3.6k points) | 2 views

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GATE2009-44 Video Solution
The following key values are inserted into a $B+$ - tree in which order of the internal nodes is $3$, and that of the leaf nodes is $2$, in the sequence given below. The order of internal nodes is the maximum number of tree pointers in each node, and the ... $1$ The maximum number of times leaf nodes would get split up as a result of these insertions is $2$ $3$ $4$ $5$

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2005-77, ISRO2016-55 Video Solution
The relation book (title,price) contains the titles and prices of different books. Assuming that no two books have the same price, what does the following SQL query list? select title from book as B where (select count(*) from ... books Title of the fifth most inexpensive book Title of the fifth most expensive book Titles of the five most expensive books

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2007-63, ISRO2016-59 Video Solution
The order of a leaf node in a B$^+$ - tree is the maximum number of (value, data record pointer) pairs it can hold. Given that the block size is $1K$ $bytes$, data record pointer is $7$ $bytes$ long, the value field is $9$ $bytes$ long and a block pointer is $6$ $bytes$ long, what is the order of the leaf node? $63$ $64$ $67$ $68$

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2012-15 Video Solution
Which of the following statements are TRUE about an SQL query? P : An SQL query can contain a HAVING clause even if it does not have a GROUP BY clause Q : An SQL query can contain a HAVING clause only if it has a GROUP BY clause R : All attributes used in ... Not all attributes used in the GROUP BY clause need to appear in the SELECT clause P and R P and S Q and R Q and S

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2009-45 Video Solution
Let $R$ and $S$ be relational schemes such that $R=\{a,b,c\}$ and $S=\{c\}.$ Now consider the following queries on the database: $\pi_{R-S}(r) - \pi_{R-S} \left (\pi_{R-S} (r) \times s - \pi_{R-S,S}(r)\right )$ ... .a,R.b From R,S Where R.c = S.c Which of the above queries are equivalent? $1$ and $2$ $1$ and $3$ $2$ and $4$ $3$ and $4$

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2017-1-42 Video Solution
In a database system, unique timestamps are assigned to each transaction using Lamport's logical clock. Let $TS(T_{1})$ and $TS(T_{2})$ be the timestamps of transactions $T_{1}$ and $T_{2}$ respectively. Besides, $T_{1}$ ... starvation-free. The database system is starvation-free, but not deadlock-free. The database system is neither deadlock-free nor starvation-free.

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2006-20, ISRO2015-17 Video Solution
Consider the following log sequence of two transactions on a bank account, with initial balance $12000,$ that transfer $2000$ to a mortgage payment and then apply a $5\%$ interest. T1 start T1 B old $=1200$ new $=10000$ T1 ... $2$ and $3$ because transaction T1 has committed We can apply redo and undo operations in arbitrary order because they are idempotent

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2009-55 Video Solution
Consider the following relational schema: $\text{Suppliers}(\underline{\text{sid:integer}},\text{ sname:string, city:string, street:string})$ $\text{Parts}(\underline{\text{pid:integer}}, \text{ pname:string, color:string})$ ... of all suppliers who have supplied only non-blue part. Find the names of all suppliers who have not supplied only blue parts.

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2007-60 Video Solution
Consider the relation employee(name, sex, supervisorName) with name as the key, supervisorName gives the name of the supervisor of the employee under consideration. What does the following Tuple Relational Calculus query produce? ... immediate male subordinates. Names of employees with no immediate female subordinates. Names of employees with a female supervisor.

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE1999-2.7, UGCNET-June2014-III-25 Video Solution

asked Apr 18 in Databases by admin (3.6k points) | 3 views

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GATE2010-20 Video Solution
Which of the following concurrency control protocols ensure both conflict serializability and freedom from deadlock? 2-phase locking Time-stamp ordering I only II only Both I and II Neither I nor II

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2012-50 Video Solution
Consider the following relations $A, B$ and $C:$ ... is the same as that of $A$. $(A\cup B)\bowtie _{A.Id > 40 \vee C.Id < 15} C$ $7$ $4$ $5$ $9$

asked Apr 18 in Databases by admin (3.6k points) | 2 views

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GATE2007-61 Video Solution
Consider the table employee(empId, name, department, salary) and the two queries $Q_1, \, Q_2$ below. Assuming that department 5 has more than one employee, and we want to find the employees who get higher salary than anyone in the department 5, which one ... $Q_1$ and $Q_2$ produce the same answer Neither $Q_1$ nor $Q_2$ is the correct query

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2008-69 Video Solution
Consider the following relational schemes for a library database: Book (Title, Author, Catalog_no, Publisher, Year, Price) Collection(Title, Author, Catalog_no) with the following functional dependencies: $\text{Title Author }\rightarrow\text{ Catalog_no}$ ... $3NF$ only Book is in $2NF$ and Collection in $3NF$ Both Book and Collection are in $2NF$ only

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2009-56 Video Solution
Consider the following relational schema: $\text{Suppliers}(\underline{\text{sid:integer}},\text{ sname:string, city:string, street:string})$ $\text{Parts}(\underline{\text{pid:integer}}, \text{ pname:string, color:string})$ ... $3NF$ but not in $\text{BCNF}$ The schema is in $2NF$ but not in $3NF$ The schema is not in $2NF$

asked Apr 18 in Databases by admin (3.6k points) | 2 views

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GATE2008-82 Video Solution
Consider the following $ER$ diagram The minimum number of tables needed to represent $M$, $N$, $P$, $R1$, $R2$ is $2$ $3$ $4$ $5$

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2015-2-46 Video Solution
Consider a simple checkpointing protocol and the following set of operations in the log. (start, T4); (write, T4, y, 2, 3); (start, T1); (commit, T4); (write, T1, z, 5, 7); (checkpoint); (start, T2); (write, T2, x, 1, 9); (commit, T2); (start, T3); (write, ... Undo: T3, T1; Redo: T2 Undo: T3, T1; Redo: T2, T4 Undo: none; Redo: T2, T4, T3, T1 Undo: T3, T1, T4; Redo: T2

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2006-67 Video Solution
Consider the relation account (customer, balance) where the customer is a primary key and there are no null values. We would like to rank customers according to decreasing balance. The customer with the largest balance gets rank 1. Ties are not broke but ranks are skipped ... ranks using ODBC. Which two of the above statements are correct? 2 and 5 1 and 3 1 and 4 3 and 5

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2010-18 Video Solution
Consider a $B^+$-tree in which the maximum number of keys in a node is $5$. What is the minimum number of keys in any non-root node? $1$ $2$ $3$ $4$

asked Apr 18 in Databases by admin (3.6k points) | 8 views

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GATE1999-1.18, ISRO2016-53 Video Solution
Consider the join of a relation $R$ with a relation $S$. If $R$ has $m$ tuples and $S$ has $n$ tuples then the maximum and minimum sizes of the join respectively are $m+n$ and $0$ $mn$ and $0$ $m+n$ and $|m-n|$ $mn$ and $m+n$

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2006-IT-85 Video Solution
Consider a database with three relation instances shown below. The primary keys for the Drivers and Cars relation are did and cid respectively and the records are stored in ascending order of these primary keys as given in the tables. No indexing is available in the database. ... key, then $n$ lies in the range: $36 - 40$ $44 - 48$ $60 - 64$ $100 - 104$

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2017-1-41 Video Solution
Consider a database that has the relation schemas EMP(EmpId, EmpName, DeptId), and DEPT(DeptName, DeptId). Note that the DeptId can be permitted to be NULL in the relation EMP. Consider the following queries on the database expressed in tuple relational calculus. {$t$ | ... } Which of the above queries are safe? I and II only I and III only II and III only I, II and III

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2004-14 Video Solution
Consider the following relation schema pertaining to a students database: Students (rollno, name, address) Enroll (rollno, courseno, coursename) where the primary keys are shown underlined. The number of tuples in the student and Enroll tables are $120$ and $8$ respectively. What ... (Student * Enroll), where *' denotes natural join? $8, 8$ $120, 8$ $960, 8$ $960, 120$

asked Apr 18 in Databases by admin (3.6k points) | 2 views

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GATE1998-26 Video Solution
Consider the following database relations containing the attributes Book_id Subject_Category_of_book Name_of_Author Nationality_of_Author With Book_id as the primary key. What is the highest normal form satisfied by this relation? Suppose the attributes Book_title and ... to {Name_of_Author, Book_title}, what will be the highest normal form satisfied by the relation?

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2016-1-51 Video Solution
Consider the following two phase locking protocol. Suppose a transaction $T$ accesses (for read or write operations), a certain set of objects $\{O_1,\ldots,O_k \}$. This is done in the following ... -freedom guarantee neither serializability nor deadlock-freedom guarantee serializability but not deadlock-freedom guarantee deadlock-freedom but not serializability.

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2005-IT-23, ISRO2017-67 Video Solution
A B-Tree used as an index for a large database table has four levels including the root node. If a new key is inserted in this index, then the maximum number of nodes that could be newly created in the process are $5$ $4$ $3$ $2$

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2008-70 Video Solution
Consider a file of $16384$ records. Each record is $32$ $bytes$ long and its key field is of size $6$ $bytes$. The file is ordered on a non-key field, and the file organization is unspanned. The file is stored in a file system with block size $1024$ $bytes$, ... -level blocks in the multi-level index are respectively $8$ and $0$ $128$ and $6$ $256$ and $4$ $512$ and $5$

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2016-2-51 Video Solution
Consider the following database schedule with two transactions $T_{1}$ and $T_{2}$ ... schedule is TRUE? $S$ is non-recoverable. $S$ is recoverable, but has a cascading abort. $S$ does not have a cascading abort. $S$ is strict.

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2007-59 Video Solution
Information about a collection of students is given by the relation $\text{studInfo(}\underline{\text{studId}},\text{ name, sex)}$. The relation $\text{enroll(}{\text{studId}},{\text{ courseId}})$ gives which student has enrolled for ( ... Courses in which a proper subset of female students are enrolled. Courses in which only male students are enrolled. None of the above

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2014-1-22 Video Solution
Given the following statements: S1: A foreign key declaration can always be replaced by an equivalent check assertion in SQL. S2: Given the table $R(a,b,c)$ where $a$ and $b$ together form the primary key, the following is a valid table definition. CREATE TABLE S ... ? S1 is TRUE and S2 is FALSE Both S1 and S2 are TRUE S1 is FALSE and S2 is TRUE Both S1 and S2 are FALSE

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2017-2-19 Video Solution
Consider the following tables $T1$ and $T2.$ ... to delete record $\langle 3, 8 \rangle$ from the table $T1,$ the number of additional records that need to be deleted from table $T1$ is _______

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2006-68 Video Solution
Consider the relation enrolled (student, course) in which (student, course) is the primary key, and the relation paid (student, amount) where student is the primary key. Assume no null values and no foreign keys or integrity ... which Query3 returns strictly fewer rows than Query2 There exist databases for which Query4 will encounter an integrity violation at runtime

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2014-2-54 Video Solution
SQL allows duplicate tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below: select * from R where a in (select S.a from S) select R.* ... distinct a from S) as S1 where R.a=S1.a select R.* from R,S where R.a=S.a and is unique R

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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GATE2012-27 Video Solution
Consider the following transactions with data items $P$ and $Q$ initialized to zero: ${\begin{array}{|c|l|r|c|}\hline \textbf{$ ... leads to a serializable schedule a schedule that is not conflict serializable a conflict serializable schedule a schedule for which a precedence graph cannot be drawn

asked Apr 18 in Databases by admin (3.6k points) | 1 view

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