# Deloitte USI Interview Questions with Answers

8 previously-asked interview questions from Deloitte USI's hiring process, each with the correct answer and a worked explanation. Written against the company's actual test pattern.

_Source: Astra (https://useastra.in). Updated 2026-09-05._

### 1. What is the difference between DELETE and DROP in SQL?

**Answer:** DELETE removes selected rows from a table and can be rolled back; the table structure remains. DROP removes the entire table including its structure, data, and indexes. DELETE is DML, while DROP is DDL.

**Explanation:** DELETE removes rows; DROP removes the whole table.

### 2. What is a foreign key and what is referential integrity?

**Answer:** A foreign key is a column that references the primary key of another table. Referential integrity is the rule that a foreign key value must either match an existing primary key or be null, keeping relationships between tables valid.

**Explanation:** Foreign key links tables; referential integrity keeps the link valid.

### 3. In Python, what is the difference between a list and a tuple?

**Answer:** A list is mutable, so its elements can change, and it is defined with square brackets. A tuple is immutable, defined with parentheses, and is usually faster and can be used as a dictionary key. Choose a tuple for fixed collections and a list for changing ones.

**Explanation:** List is mutable; tuple is immutable.

### 4. What is the difference between an inner join and an outer join?

**Answer:** An inner join returns only rows with matches in both tables. An outer join also returns unmatched rows: a left outer join keeps all left rows, a right outer join all right rows, and a full outer join all rows from both, filling missing columns with null.

**Explanation:** Inner returns matches only; outer also keeps unmatched rows.

### 5. What is object oriented programming?

**Answer:** OOP is a paradigm that structures software as objects combining data and behaviour. Its principles are encapsulation, inheritance, polymorphism, and abstraction, which improve reusability, maintainability, and modelling of real world entities.

**Explanation:** Objects combining data and behaviour; four core principles.

### 6. Deloitte uses the Versant spoken-English test for some roles. How would you prepare for it?

**Answer:** Practise reading sentences aloud clearly, repeating spoken sentences, answering short questions, and retelling stories, since those are the task types. Speak at a natural pace with clear pronunciation, use a quiet room with a good mic, and aim for fluency over a heavy accent.

**Explanation:** Practise the task types; clear, fluent speech in a quiet setup.

### 7. Tell me about yourself.

**Answer:** Give a focused 60 to 90 second overview: your degree, key technical and analytical skills, a project or internship with its impact, and why you are drawn to Deloitte. Keep it structured and relevant to an analyst role.

**Explanation:** Structured pitch: background, skills, project, fit.

### 8. Why do you want to join Deloitte?

**Answer:** Mention Deloitte global brand, its work with major clients across consulting and technology, the strong learning and mentorship culture, and clear career paths. Connect it to your goal of building analytical and professional skills early.

**Explanation:** Global brand, client work, learning culture, career path.

More Deloitte USI preparation, including the full recruitment process: https://useastra.in/campus/deloitte