1 : 1 SQL Intermediate Interview Session | SQL Interview Q&A | SQL Training | Ivy Pro School

Most Common SQL Interview Questions are as follows:

1. What is Database?
A database is an organized collection of data, stored and retrieved digitally from a remote or local computer system. Databases can be vast and complex, and such databases are developed using fixed design and modeling approaches.

2. What is DBMS?
DBMS stands for Database Management System. DBMS is a system software responsible for the creation, retrieval, updation and management of the database. It ensures that our data is consistent, organized and is easily accessible by serving as an interface between the database and its end-users or application software.

3. What is RDBMS? How is it different from DBMS?
RDBMS stands for Relational Database Management System. The key difference here, compared to DBMS, is that RDBMS stores data in the form of a collection of tables and relations can be defined between the common fields of these tables. Most modern database management systems like MySQL, Microsoft SQL Server, Oracle, IBM DB2, and Amazon Redshift are based on RDBMS.

4. What is SQL?
SQL stands for Structured Query Language. It is the standard language for relational database management systems. It is especially useful in handling organized data comprised of entities (variables) and relations between different entities of the data.

5. What is the difference between SQL and MySQL?
SQL is a standard language for retrieving and manipulating structured databases. On the contrary, MySQL is a relational database management system, like SQL Server, Oracle, or IBM DB2, that is used to manage SQL databases.

6. What are Tables and Fields?
A table is an organized collection of data stored in the form of rows and columns. Columns can be categorized as vertical and rows as horizontal. The columns in a table are called fields while the rows can be referred to as records.

7. What are Constraints in SQL?
Constraints are used to specify the rules concerning data in the table. It can be applied for single or multiple fields in an SQL table during the creation of a table or after creating using the ALTER TABLE command. The constraints are:

- NOT NULL - Restricts NULL value from being inserted into a column.
- CHECK - Verifies that all values in a field satisfy a condition.
- DEFAULT - Automatically assigns a default value if no value has been specified for the field.
- UNIQUE - Ensures unique values to be inserted into the field.
- INDEX - Indexes a field providing faster retrieval of records.
- PRIMARY KEY - Uniquely identifies each record in a table.
- FOREIGN KEY - Ensures referential integrity for a record in another table.

8. What is a Primary Key?
The PRIMARY KEY constraint uniquely identifies each row in a table. It must contain UNIQUE values and has an implicit NOT NULL constraint.
A table in SQL is strictly restricted to have one and only one primary key, which is comprised of single or multiple fields (columns).

9. What is a UNIQUE constraint?
A UNIQUE constraint ensures that all values in a column are different. This provides uniqueness for the column(s) and helps identify each row uniquely. Unlike the primary key, there can be multiple unique constraints defined per table. The code syntax for UNIQUE is quite similar to that of PRIMARY KEY and can be used interchangeably.

10. What is a Join? List its different types.

The SQL Join clause is used to combine records (rows) from two or more tables in a SQL database based on a related column between the two.
There are four different types of JOINs in SQL:

- (INNER) JOIN: Retrieves records that have matching values in both tables involved in the join. This is the widely used join for queries.
- LEFT (OUTER) JOIN: Retrieves all the records/rows from the left and the matched records/rows from the right table.
- RIGHT (OUTER) JOIN: Retrieves all the records/rows from the right and the matched records/rows from the left table.
- FULL (OUTER) JOIN: Retrieves all the records where there is a match in either the left or right table.

11. What is a Subquery? What are its types?
A subquery is a query within another query, also known as a nested query or inner query. It is used to restrict or enhance the data to be queried by the main query, thus restricting or enhancing the output of the main query respectively.

12. What are UNION, MINUS, and INTERSECT commands?
The UNION operator combines and returns the result-set retrieved by two or more SELECT statements.
The MINUS operator in SQL is used to remove duplicates from the result-set obtained by the second SELECT query from the result-set obtained by the first SELECT query and then return the filtered results from the first.
The INTERSECT clause in SQL combines the result-set fetched by the two SELECT statements where records from one match the other and then returns this intersection of result-sets.

[letsgothrough]

Very informative.. Very patiently he answered his questions and this is called confidence.. Didn't feel like interview session

[world_of_sports]

The Interviewer has really got some great endurance 😂...Not even for a single question, the applicant answered directly.

[SagarKumar-dbxy]

Feedback at the end by interviewer was Damn Impressive. Really impressed by Sir.

[deepalipatil]

Answer for 24:30 question is to use cross join. Interviewer was expecting you to say that

[somnathbanerjee]

To answer the question: "what are the properties of good database design?"... We would directly start from ACID property of database. Prior to this characteristic, we would define some principles of good database design such as usability, integrity, security etc. Examples are required in answering scenario-based questions. I would feel nervous though. :-)
Overall good. I really appreciate Ivy on this kind of real-time engaging video update. #Happy Learning

[adhirajmajumder]

Thank you, but I like to say Excel can deal with only row data but SQL can deal with unlimited amount of data. Cartesian might be cross product join

[ebtesamkhan]

Thank you so much for this video. It's really really helpful.

[machhindrasmathematics]

Salute to interviewer... And his expertise in all the sections

[girldreams]

Much needed video at this time.. thank you for uploading ❤️

[subhashg]

Great informative video sir!!
Come to know some now contact also..

[sajidulahmed]

Great and honest feedback from the Interviewer!

[manojpawar]

q2) Duplicate emails

select email, count(Email)as cnt
from person
group by email
having count(email)>1

[aryanshinde]

Relational database management is advanced version of database. Stored data in tubular formate. A relational database is type of database that Store and provides To access data points that are relate to one another

[satyajitpramanik]

Select id
From(Select id, rank() over(order by salary desc) as rownum
From salary)
Where rownum=2

[chandukolanu]

The interview is expecting the candidate to say it is a cross join. This retieves the table based on the Cartesian Product. Which is why it doesn't require identical columns as reference to join tables.

[abiodunmabidemi]

The interview is real but damn, the interviewer drilled the hell of him, sql technical interview can’t be anymore mean or dreaded. His onboarding salary is worth that of the CEO.

[pankajverma-xmqv]

why its too complicated once he join the brand a brand should educate him if he already has an experience .If he get selected what package he can expect on this type of level interview????

[swamivivekananda-cyclonicm]

More than answers we learn more than questions and last 10 min

[chandhuchandhu]

Could you please post sap hana modeller perspective live interview

[subhendudas]

Not able to find the licence folder in c drive...where should I paste the licence key