All India Computer Science Engineering (CSE) Group

The all comparison checker is used to check “each and every” condition. The “each” and “every” comparison checkers do not exist in SQL.

BIOS is used by the operating system. It is used to configure and identify the hardware in a system such as the hard drive, floppy drive, optical drive, CPU, and memory.

Page faults occur when a process tries to access a block page of the memory and that page is not stored in RAM (Read only memory) or memory.

A correlated sub-query is the one that uses the correlation name of an outer query.

SQL subqueries that can occur wherever a value is permitted provided the subquery gives only one tuple with a single attribute are called Scalar subqueries. Scalar Subqueries can be used in the SQL update statement when they are used under the set clause.

The command interpreter is also called the shell.

The first MS Windows operating system was introduced in early 1985.

The maximum length of the filename is 8 characters in the DOS operating system. It is commonly known as an 8.3 filename.

Booting is a process of the restart the computer. After restarting it, there is no software in the computer's main memory.

The FAT stands for File allocation table. The FAT is a file system architecture. It is used in computer systems and memory cards. A FAT of the contents of a computer disk indicates which field is used for which file.

The .txt file extension is a standard text document extension that contains the unformatted text. It is the default file extension for the notepad.

The first operating system was developed in the early 1950's. It was also called a single-stream batch processing system because it presented data in groups.

Oracle is an RDBMS (Relational Database Management System). It is known as Oracle Database, Oracle DB, or Oracle Only. The first database for enterprise grid computing is the Oracle database.

S1: r1(x) r1(y) r2(x) r2(y) w2(y) w1(x)

Precedence Graph:

S2:r1(x) r2(x) r2(y) w2(y) r1(y) w1(x)

Precedence Graph:

There exists a Cycle in Precedence of S1. Hence S1 is not Conflict Serializable.

Whereas S2 is Conflict Serializable.

Serial schedule is possible only when precedence graph doesn’t contain cycle. If precedence graph contains a cycle, it means schedule is not conflict serializable.
Breadth first search and Depth first search of a graph are possible even if graph contains cycle.
Topological sort in a graph will not work if graph contains a cycle.

Consider a directed acyclic graph:

 

Here Two orders possible: V₂, V₃, V₁, V₄, V₅, V₆ OR V₃, V₂, V₁, V₄, V₅, V₆.
In case of ascending order of transaction indices, two non-conflicting schedules can occur simultaneously.

P and Q are initialized to Zero, write operation on P and Q will be executed.
Consider any non-serial schedule like R₁(P), R₂(Q), R₁(Q), R₂(P), W₁(Q), W₂(P). R₁(P) conflicts with W₂(P) Hence T₁ must be before T₂. R₂(Q) conflicts with W₁(Q) Hence T₂ must be before T₁. There is no serial schedule that satisfies both of them hence it does not conflict with serializable.
Hence the correct answer is a schedule that is not conflict serializable.

A schedule is said to be conflict-serializable when the schedule is conflict-equivalent to one or more serial schedules.  Conflict-serializability is that a schedule is conflict-serializable if and only if its precedence graph/serializability graph, when only committed transactions are considered, is acyclic.

As an initial step in both serial schedules, one of the transactions reads the value written by the other transaction. As a result, any non-serial T₁ and T₂ interleaving will not be conflict serializable.

Hence the correct answer is a schedule that is not conflict serializable.

Concept:
Considering all nodes are completely full means every node has N − 1 key.
If a new key is inserted, then at every level there will be a new node created, and in the worst-case root node will also be broken into two parts. Since we have 4 levels, then 5 new nodes will be created
Additional Information:
Diagram needs to be updated
First, the overflow happens at the leaf, and second on the parent of that leaf, and so on until the last overflow happens at the root node.

Key Points
If the database table has h levels and the level of the root node is 1 then on a new key insertion, the maximum number of nodes newly created is h + 1

A non-root node in a B-tree of order n contains at least (n – 1)/2 keys. And contains a maximum of (n – 1) keys and n sons.

I and J are conflicting if they are operations by different transactions on the same data item, and at least one of them is a write operation.

CONCEPT:
B-tree is a self-balancing search tree that allows all operations i.e. searching, insertion, deletion in logarithmic(log) time.
Key Points
A B-tree of order m must satisfy the following properties:

Hence, if a node has K children in B tree, then the node contains exactly k-1 keys.

At every level, one new node is created except root, at two new nodes is created.
Tips and Tricks:
If database table has h levels and level of root node is 0 then on a new key insertion, maximum number of nodes newly created is h + 2
New nodes = 7 + 2 = 9
If database table has h levels and level of root node is 1 then on a new key insertion, maximum number of nodes newly created is h + 1

In external memory, the data is transferred in form of blocks. These blocks have data valued and pointers. And B-tree can hold both the data values and pointers. So B-tree is used as an external memory data structure.

If s splits occur in a B-tree, 2s + 1 nodes are written (2 halves of each split and the parent of the last node split). So, if 5 splits occurred, then 2 * 5 + 1, i.e. 11 nodes are written.

A B-tree of order m of height h will have the maximum number of keys when all nodes are completely filled. So, the B-tree will have n = (m^h+1 – 1) keys in this situation. So, required number of maximum keys = 4³⁺¹ – 1 = 256 – 1 = 255.

2-3-4 trees are isometric of Red-Black trees. It means that, for every 2-3-4 tree, there exists a Red-Black tree with data elements in the same order.

B-tree of order n and with height k has best case height h, where h = logn (k+1) – 1. The best case occurs when all the nodes are completely filled with keys.

The average probability of the split is 1/([m / 2] – 1), where m is the order of B-tree. So, if m larger, the probability of split will be less.

char si [] = "India is great";

The above declaration is a dynamic allocation of array name si of character datatype.

Hence the correct answer is 15.

Arrays are of fixed size. If we insert elements less than the allocated size, unoccupied positions can’t be used again. Wastage will occur in memory.

Array name: A

To access 3rd element in an array A[2] or 2[A] is used.  Therefore Both A[2] and 2[A] represent the value 3

An array is defined as the collection of similar types of data items stored at contiguous memory locations. Arrays are the derived data type in C programming language which can store the primitive type of data such as int, char, double, float, etc. C array is beneficial if you have to store similar elements.

int array[] = {2, 3, 4, 5}; This array storage be like, 

The above array at index I can be accessed by, a[i], i[a], *(a+i) or *(i+a) all the above representations all are equal and gives the i th index value.

printf(%d', 2[array]); So, it gives the 2nd  index value. i.e 4.

Hence the correct answer is 4.

 Whenever a particular memory location is referred to, it is likely that the locations nearby are also referred, arrays are stored as contiguous blocks in memory, so if you want to access array elements, spatial locality makes it to access quickly.

Array:
An array is a group of data components that are stored in the same memory region at the same time. It is the most basic data structure, in which each data piece may be retrieved simply by its index number alone.

Array initialize:
Only square brackets [ ] must be used for declaring an array. The given {}, () are not useful for array initialization.
int arr[5]={11,12,15,16,19} is correct.
The above statement can store the 5 elements in a continuous manner. consider the array base address is 100.

Hence the correct answer is  int arr[5]={11,12,15,16,19}.

Trying to access an element beyond the limits of an array gives ArrayIndexOutOfBoundsException.

Let's take an example to understand this - 
Array - [2,6,7,0,15], where 2 is the lower bound and 15 is the upper bound element.

The K is the variable that holds the index of the array. While the LA is the name of the array. A loop is used to visit to traverse the elements from LB to UB.

The K holds the index of element 2 which is 0 and reaches index 4 of element 15.

The LA array using K traverse all the elements in the array. So, Option 2 will be the answer. 

The syntax to declare multidimensional array in java is either int[][] arr; or int arr[][];

This is the syntax to initialize an array in C.

Array a

for(I = 2; I < 6; ++i)            // initially i = 2 and 2< 6(true)
a [a [i] ] = a [i];         
Iteration 1:
i = 2;
a[a[2]] = a[2]
a[3] = [3]

Iteration 2:
When i = 3, 3 < 6 (true)
a[a[3]] = a[3]
a[3] = 3              // as in iteration 1, a[3] becomes was 3

Iteration 3:
When i = 4
a[a[4]] = a[4]
a[5] = 5

Iteration 4:
When i = 5, 5 < 6 (true)
a[a[5]] = a[5]
a[5] = 5                // as in iteration 3 a[5] becomes 5.

In next iteration i becomes and condition 6 < 6 false here.
Content of array A are as follows:

Finally, it prints: 1 2 3 3 5 5 7 8

An array is a collection of items stored at contiguous memory locations. The idea is to store multiple items of the same type together.

When an array is used as a value and array name represents the address of the first element. When an array is not used as a value its name represents the whole array.

Array name is a type of name or a type of any element name that is share by all elements of an array but its indexes are different. Array name handle as a constant pointer, it can never change during execution of a program. Array name is also used to reach its all element.

Therefore Option 3 is correct

Where \0 is a null character 
After *p = '0';   \\s1[2] = '0'
100  101 102 103  104

printf(“%s”, s1) will print all starting from address location 100 until the null character.
Output: 1204 

Array contains elements only of the same type.

Note that int arr[]; is declaration whereas int arr[] = new int[3]; is to instantiate an array.

*(arr[1] + 9) can be written as arr[1][9].
as C doesn't follow bound check and follow the row major ordering
arr[1][5] = arr[2][0]  // arr[1][4] will be first row of array and then arr[2][0] will be second row of array 
arr[1][6] = arr[2][1]
arr[1][7] = arr[2][2]
arr[1][8] = arr[2][3]
arr[1][9] = arr[2][4]
arr[2][4] = 10*i + j = 10*2+4 = 24

Option 4 is the answer.