SQL Interview Questions

The full form of SQL is Structured query language, which lets to access and manipulate the database. Structured query language became the standard of American National Standard Institute (ANSC) in 1986, according to which it is the standard language of relational database management systems.

SQL became the standard of the International Organisation for Standardisation in 1987. It used to communicate with the database. SQL is usually pronounced as see-qweel. SQL was earlier known as SEQUEL ( Structured English Query Language) designed to update, add or remove the data from within the database.

Questions

  1. What are joins in SQL?
  2. What is the difference between SQL and MySQL?
  3. What are Constraints?
  4. What is the primary key?
  5. What do you mean by table and field in SQL?
  6. What are the different subsets of SQL?
  7. What do you mean by DBMS?
  8. What are the different types of DBMS?
  9. What is a Unique key? 
  10. What is a foreign key?

Pl SQL interview questions

Pl/SQL is Oracle Corporation’s procedural extension for SQL, where PL is a Procedural language for SQL ( Structured query language). It is usually found in Oracle’s database. The function of Pl/SQL is to write procedures, program blocks, functions, triggers, and packages. Pl/SQL is used to format, build, and display the user’s screens, webpages, and reports. The most commonly asked Pl/SQL interview questions are:

  1. What is Pl/SQL?
  2.  Explain the uses of the cursor
  3.  What are the two types of exception?
  4.  Explain Raise application error.
  5.  Explain Commit, Rollback, and Savepoint.
  6. Explain the mutating table error.
  7.  What operators deal with NULL?
  8.  Explain three basic parts of the trigger.
  9.  What are the character functions?
  10.  What is an intersect?

SQL interview questions and answers

SQL is a Structured query language that can access and manipulate the database. It is one of the most widely used programming languages. It is a language used to interact with the database. It is the standard language of the Relational database management system. In interviews, candidates will have to answer the questions asked regarding the SQL programming language, and examples of such questions asked are :

  1. What is SQL?
  2. When did SQL appear?
  3. Does SQL support programming?
  4. What are the usages of SQL?
  5.  What are the subsets of SQL?
  6.  What is data manipulation language?
  7. What is the data definition language?
  8. What is a database?
  9. What is the difference between a unique key and primary key?
  10.  What is DBMS?

SQL interview questions for developers

The responsibilities of SQL developers include developing the SQL database and writing an application to interface with the SQL database, writing, and testing codes as well. SQL Developer is held responsible for database related jobs or tasks. SQL developers are expected to be aware of the functions of Pl/SQL as well. The interview questions for developers might be slightly different from the others. 

Questions:

  1.  What is SQL?
  2. What is normalisation?
  3.  What is the purpose of normalization?
  4.  What is a self join?
  5.  What are DMVs?
  6.  How are transactions used?
  7. What is DBCC commands?
  8.  What is CTE?
  9.  What is a query execution plan?
  10.  What is a view?

Basic SQL interview questions

The structured query language is the most commonly used programming language to communicate with the database. Candidates will have to face many questions regarding SQL during the interviews, which might range between easy to difficult. There are few basic questions regarding SQL that has to acknowledged by the candidates before attending an interview:

  1. What is SQL?
  2. What is DBMS?
  3. What is a database?
  4. What are Constraints?
  5. What are field and tables?
  6. What is the primary key?
  7. What is a unique key?
  8. What is a foreign key?
  9. What is join?
  10. What are the types of join?

SQL interview questions for testers

SQL is a standard language for the relational database management system. It used to insert, update, and modify the data. The knowledge of Structured query language is essential for a tester. The knowledge of database structure and SQL commands allows testers to be more effective in testing software applications. SQL interview questions that are most commonly asked for testers are :

  1. What is performance testing?
  2. What is SQL?
  3. What is DBMS?
  4. What are the tables in SQL?
  5. What are the different classes used in SQL?
  6. What is DML?
  7. What is DCL commands?
  8. Does QTP support SQL queries?
  9. How is data load testing performed?
  10. What is data-driven testing?

SQL interview questions for experienced

The structured query language is a widely-used programming language. SQL is pronounced as see-qweel. Questions asked during the interviews regarding SQL may differ for a fresher and experienced person. Usually, for experienced candidates, the questions would be more intense compared with the Experienced candidates who are expected to have more knowledge about the SQL.

Questions:

  1. Explain the meaning of the index.
  2. Are NULL values equal to zero?
  3. Data disk gets overloaded. What would you do?
  4. Explain what ‘auto-increment’ is?
  5.  Using an existing table makes an empty one.
  6. What are the variables of SQL?
  7. How would you retrieve common records from two tables?
  8.  What is ‘data warehouse’? And what does it do?
  9. How would you check your SQL version?
  10.   You forgot your root password, what would you do?

SQL interview questions for Freshers

SQL is a domain-specific language used in programming and is designed to manage data in a relational database management system. The questions asked during the interviews differ from person to person. The Freshers would have an advantage for not being experienced candidates because the questions asked to the candidates would be easier when compared to experienced candidates.

  1. What is SQL?
  2. Why use SQL?
  3. What is a database?
  4. What is the primary key?
  5. What is the difference between primary key and a unique key?
  6. What is a unique key?
  7. What is RDBMS?
  8.  What tables and fields?
  9. Explain about SQL joins.
  10.  What are views in SQL?

Aadvanced SQL interview questions

The knowledge about the functions and commands of Structured query language is essential before attending SQL interviews. The difficulty level of the questions asked during the interviews may differ. There might be times when you’ll have to face the advanced questions regarding SQL. The few advanced questions regarding Structured query language during the interviews are:

  1. Is there any way to find out the column indexed or not? If yes, how?
  2. Explain Rank as an aggregate function with example.
  3.  What is the difference unique and distinct?
  4.  What is dense_rank?
  5.  What is the difference between union and union of all operators?
  6.  How to find all details about constraints?
  7.  What is subquery?
  8.  Explain co-related- subquery.
  9.  What is a materialized view?
  10.  What is a unique index?

Top SQL interview questions

SQL is Structured Query Language, a computer language for storing, manipulating, and retrieving data stored in the relational database. You should be kneeling aware of the depths of SQL to answer the top questions. The questions asked during the interviews wouldn’t be the same, but few top questions can be expected regarding SQL during the interviews, and they are:

  1. What is a query?
  2. What is a subquery?
  3. How to select unique records from the table?
  4. What is an ALIAS command?
  5. What is Clause?
  6. What is collation?
  7. What are the different types of collation sensitivity?
  8. What is user-defined sensitivity?
  9. What is cross-join?
  10. What is self-join?

Tricky SQL interview questions

The structured query language is used to perform certain tasks such as performance data from the database or retrieve data from the database. It has a wide range of functions from which many tricky questions can be formed. Candidates should have a good knowledge of SQL to answer the tricky questions regarding SQL asked during the interviews. A few such tricky questions are:

  1. How to display 1 to 100 numbers with a query?
  2. How to find the count of duplicate rows?
  3. How to show maximum marks and minimum marks together from the student table?
  4. How to display the string vertically in oracle?
  5. How to remove duplicate rows from the table?
  6. How to display the date in the DD-Month-YYYY table?
  7. What is the query to drop all user tables from the oracle?
  8. How to get the number of weekends of the current month?
  9. What is the query to fetch the last day of the previous month from the oracle?
  10. Write the query to find the repeated queries from your name?

Ms. SQL interview questions

Ms. SQL is the short form of Microsoft SQL Server. Ms. SQL is a relational database management system (RDMS) developed by Microsoft. It is a relational web hosting database used to store information like a website blog post or user information. This is developed for the basic function of storing, retrieving data as required by other applications. The few commonly asked Ms. SQL interview questions are:

  1. What is MSSQL?
  2.  What is a cursor and index in SQL?
  3.  What are the types of subqueries?
  4. Explain the trigger, and it’s typing.
  5.  What is the SQL profiler?
  6.  Explain subquery and state it’s properties.
  7. Explain magic tables in the SQL server.
  8.  Explain TABLE SAMPLE.
  9. What is the filter index?
  10.  What are the CDC and SQL injection?

Data analyst SQL interview questions

SQL data analyst is a data scientist who uses the SQL language to interpret the data, design scripts, and programs to perform specific database functions. The main responsibility of data analysts revolves in analyzing and maintaining data. Data analysis of SQL requires skills which is in high demand in the present. The few questions that SQL data analyst might come across during interviews are:

  1. What are SQL and a relational database?
  2.  Explain SQL join Clause and their uses.
  3.  What is normalization and demoralization in SQL?
  4.  How have you made use of SQL previously?
  5.  What is the role of a data analyst?
  6. What is data cleansing?
  7.  Explain outliner.
  8.  Explain what is collaborative filtering.
  9.  If you make a typo in every clause of the SQL query, what would be the first error detected?
  10. Explain the difference between hash join and sort-merge join.

Technical SQL interview questions

Interviews are held to judge the abilities of the candidates. Thus, before we attend interviews, we should have acquired the knowledge regarding the interview topics. Different questions are asked during interviews. The difficulty level of questions differs every time. There’s always a technical round in interviews which the candidates have to come across to acquire a job. Few such SQL technical questions are:

  1.  What is the index?
  2. Explain the different types of indexes.
  3. What is the primary key?
  4. What is a unique key?
  5.  What is the default constraint?
  6. What is a unique constraint?
  7.  Explain the different SQL commands.
  8.  State the difference between Having and Where clause.
  9.  What is SQL?
  10. What is a database?

Business analyst SQL interview questions

Business analysts are responsible for bridging the gap between IT and business using data analysis. Business analyst helps guide businesses in improving products, processes, services, and software using data analysis. They use SQL to manipulate data in a relational database. The few examples of questions asked to this domain of SQL during interviews are:

  1.  What is a business analyst?
  2.  Why is SQL necessary for a business analyst?
  3.  What is the IN operator?
  4. What are the aggregate functions?
  5.  What is a self join?
  6. What is a cross join?
  7.  What is an inner join?
  8. What is a subquery?
  9.  What is the primary key?
  10. What is a view?

How to crack SQL interview

SQL is one of the most widely used programming languages for data analysis and data processing. For interviews of jobs related to data science such as data analyst, data scientist, and data engineer questions from Structured Query Language initially become part of the interview. 

Everyone can crack the SQL interview if we acquire the relevant knowledge about SQL functions and commands. A lot of preparation to answer the most commonly asked SQL questions would help you stay confident. Being prepared would help you to solve the questions sparing your time to work stress-free during your interview.

How to crack the interview

  • Stay prepared with enough data
  • Be aware of most commonly asked questions
  • Acquire technical knowledge of SQL

FAQ

✅ How can I prepare for the SQL interview?

If you want to prepare yourself for the SQL interview, you should be aware of certain topics that would help you easily crack your SQL interview. You acquire knowledge about keys, views, functions, joins, index, locking, transaction, and coding questions. Preparing these topics would provide confidence, and you can prepare for your SQL interview.

✅ What are the most popular SQL interview questions for data analysts?

1. Name and explain the different types of keys in SQL
2. Write an SQL query to get the records of employees whose last name begins with J.

✅ What is SQL?

SQL stands for Structured query language, one of the most widely used programming languages used to communicate within the database. SQL statements are used to update the database or retrieve the database.

✅ What are the basic SQL skills?

1. Create a database using WAMP and SQL
2. Learn to structure a database
3. To manage a database

✅ What are the questions asked in the SQL interview?

1. What is SQL, and what are its uses?
2. What is the primary key?
3. What is a database?
4. What is a unique key?
5. What are you to join?

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About the Author

Rachit believes in the power of education and has studied from the top institutes of IIIT Allahabad, IIM Calcutta, and Francois Rabelias in France. He has worked as Software Developer with Microsoft and Adobe. Post his MBA, he worked with the world’s # 1 consulting firm, The Boston Consulting Group across multiple geographies US, South-East Asia and Europe.

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