Practice IT DBMS Questions and Answers

• Which SQL constraint ensures that a column cannot have NULL values?
• Which of the following is used to enforce referential integrity?
• Which type of join returns all rows from the left table and matching rows from the right table?
• In a relational database, what is a candidate key?
• Which of the following is used to remove all records from a table without removing the table structure?
• In a relational schema, which normal form eliminates transitive dependencies (i.e., non-prime attribute depends on another non-prime attribute)?
• A transaction that reads a value then later sees a different value because another transaction updated and committed in between experiences which anomaly?
• Which of the following concurrency control methods avoids deadlocks entirely but can reduce concurrency by blocking transactions at start?
• In indexing, which tree is most commonly used for disk-based indexing because it minimizes disk seeks and keeps nodes dense?
• Which SQL isolation level allows phantom reads but prevents dirty reads and non-repeatable reads?
• Given the `SinglyLinkedList` and its `delete_node` method as provided, what will be the output of `my_list.print_list()` after the following sequence of op...
• What does re.sub(r'(\w+)', r'_\1_', 'hello world') return?
• What does [aeiou] match in a regular expression? 
• What will re.findall(r'\d+', 'abc123def45ghi') return? 
• Consider the following Java code snippet  public class Car {     private String model;     private int year;     public Car(String model, int year) ...
• You have a Python list of fruits and want to extract a specific sub-list using slicing.  Complete the missing part of the code to obtain the sub-list `['b...
• Which of the following is NOT a common type of error encountered during software development? 
• In the context of debugging an Object-Oriented program, what does "stepping over" a method call typically do in a debugger? 
• A programmer is trying to debug an issue where an `ArrayList` (or equivalent dynamic array) in their Java/Python code unexpectedly throws an  `IndexOutOfB...
• Consider a scenario in an OOP application where a `NullPointerException` (or equivalent) occurs when trying to access a member of an object. What is the mo...
• Which debugging tool allows a developer to pause program execution at specific lines, inspect variable values, and execute code step-by-step? 
• When debugging a recursive function that processes a `Tree` data structure, what is a common strategy to identify infinite recursion or incorrect base case...
• A software defect that causes a program to produce incorrect output without crashing or displaying an error message is typically classified as a: 
• Consider the following pseudo-code:   ```     function calculate(arr):         sum = 0         for i from 0 to length(arr) - 1:           ...
• Given the following Python-like code snippet:     ```python     class Counter:         def __init__(self):             self.count = 0     ...
• What will be the value of `x` after the following pseudo-code execution?  ```     x = 0     data = [10, 20, 30]     for item in data:         if...
• Consider a `Stack` data structure implemented with `push` and `pop` operations. What is the final state of the stack after the following sequence of operat...
• Examine the following Java-like code:      ```java     class Parent {         String name = "Parent";         public void display() {      ...
• What is the output of the following pseudo-code?   ```     count = 0     for i from 1 to 3:         for j from 1 to i:             count = ...
• Given a `Queue` data structure with `enqueue` and `dequeue` operations. What is the element returned by the last `dequeue` operation in the following seque...
• In an Object-Oriented program, which control flow construct is primarily used to handle unexpected events or errors that occur during program execution, su...
• Which of the following best describes the control flow when a method in a subclass overrides a method in its superclass, and an object of the subclass is r...
• Consider a `LinkedList` data structure. Which control flow statement is most appropriate for iterating through all elements of the list from head to tail?�...
• In a program that manages a collection of `Employee` objects, each with a `salary` attribute, which control flow mechanism would be most efficient to find ...
• When implementing a `Graph` traversal algorithm like Depth-First Search (DFS) recursively, what is the primary control flow mechanism that manages the orde...
• Which OOP concept directly influences control flow by allowing different implementations of a method to be called based on the type of the object at runtim...
• A program needs to process elements from a `Queue` until it becomes empty. Which control flow structure is most suitable for this task? 
• What will be the output of the following Python code: a=[1,2,3,4,5,6] print(a[-1],a[-1:],a[:-1])
• A company needs to schedule a maximum number of meetings in a single conference room. Each meeting `i` has a start time `s_i` and an finish time `f_i`. Onc...
• Consider the following C++-like pseudo-code for a binary tree traversal:     ```cpp     struct Node {         int data;         Node left;   �...