Dixit Infotech Services Oracle Database Administrator Interview Questions and Answers

Joins are used to combine data from two or more tables based on a related column.

• Types of joins include inner join, left join, right join, and full outer join.

• Inner join returns only the matching rows from both tables.

• Left join returns all rows from the left table and matching rows from the right table.

• Right join returns all rows from the right table and matching rows from the left table.

• Full outer join returns all row...read more

I am a software engineer with expertise in developing and maintaining software applications.

• Proficient in programming languages such as Java, C++, and Python

• Experienced in developing web applications using frameworks like Spring and Django

• Skilled in database management and SQL queries

• Familiar with software development methodologies like Agile and Scrum

• Strong problem-solving and analytical skills

• Excellent communication

Output details of recent 10 graduates from a table storing student details.

• Sort the table by graduation date in descending order.

• Select the top 10 rows from the sorted table.

• Output the selected rows.

Optimized approach to find third largest element from array using half traversal.

• Sort the array in descending order and return the element at index 2.

• Use a max heap to keep track of the top 3 elements while traversing the array.

• Use two variables to keep track of the second and third largest elements while traversing the array.

• Divide the array into two halves and find the maximum and second maximum in each half, then co

Answering how to print first character of words in a string using one stack and an array.

• For using one stack, push each character onto the stack and pop when a space is encountered. Print the popped character.

• For using an array, split the string into words and print the first character of each word.

• In both cases, handle edge cases like empty string and string with only one word.

Hash table. No, it is not possible to create a data structure with all operations in O(1) time.

• Hash table uses a hash function to map keys to indices in an array.

• Insertion and deletion can be done in O(1) time on average.

• Search retrieval can also be done in O(1) time on average.

• However, worst-case scenarios can result in O(n) time complexity.

• It is not possible to create a data structure with all operations in O(1) time

ACID properties ensure database transactions are reliable. Two transactions can occur simultaneously using locking and isolation.

• ACID stands for Atomicity, Consistency, Isolation, and Durability.

• Atomicity ensures that a transaction is treated as a single unit of work, either all or none of it is executed.

• Consistency ensures that a transaction brings the database from one valid state to another.

• Isolation ensures that co...read more

Indexes are used to improve query performance. Multiple clustered and non-clustered indexes can be created on a table.

• Indexes are used to quickly locate data without scanning the entire table.

• Clustered index determines the physical order of data in a table.

• Non-clustered index is a separate structure that contains a copy of the indexed columns and a pointer to the actual data.

• A table can have only one clustered index, b...read more

Given an array and a number, find if the number can be generated using sum of array members and output those numbers.

• Iterate through the array and check if the number can be generated using the sum of array members

• Use a hash table to store the difference between the number and each array element

• If the difference is found in the hash table, output the corresponding array elements

• If no such combination is found, output '

Time complexity of data structure operations

• Arrays: O(1) for access, O(n) for search/insert/delete

• Linked Lists: O(n) for access/search, O(1) for insert/delete

• Stacks/Queues: O(1) for access/insert/delete

• Hash Tables: O(1) for access/insert/delete (average case)

• Trees: O(log n) for access/search/insert/delete (balanced)

• Heaps: O(log n) for access/insert/delete

• Graphs: Varies depending on algorithm used

Span is an inline element used for styling small portions of text, while div is a block-level element used for grouping and styling larger sections of content.

• Span is an inline element, div is a block-level element

• Span is used for styling small portions of text, div is used for grouping larger sections of content

• Span does not create a new line, div creates a new block-level element