SQL Interview Questions! 🔥🚀
Basic SQL Interview Questions:
- What is SQL?
- What are the different types of SQL commands?
- What is the difference between
DDL, DML, DCL, and TCL?
- What is the difference between
SQL and MySQL?
- What is a primary key?
- What is a foreign key?
- What is a unique key?
- What is the difference between
primary key and unique key?
- What is the difference between
HAVING and WHERE?
- What are constraints in SQL? Name a few.
- What is the difference between
CHAR and VARCHAR?
- What is
Normalization? What are its types?
- What is
Denormalization?
- What is an index in SQL?
- What are the different types of indexes?
- What is the difference between
Clustered and Non-clustered indexes?
- What is an alias in SQL?
- What is the difference between
DELETE and TRUNCATE?
- What is the difference between
TRUNCATE and DROP?
- What is a
view in SQL?
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Intermediate SQL Interview Questions:
What is a
self-join?
What is an
inner join?
What is the difference between
INNER JOIN and OUTER JOIN?
What are the types of
OUTER JOIN?
What is a
cross join?
What is a
Cartesian join?
What is the difference between
UNION and UNION ALL?
What is the difference between
JOIN and UNION?
What is a
stored procedure?
What is a
trigger in SQL?
What are the different types of
triggers?
What is the difference between
HAVING and GROUP BY?
What are
subqueries?
What are
correlated subqueries?
What is an
EXISTS clause in SQL?
What is the difference between
EXISTS and IN?
What is a
cursor in SQL?
What is the difference between
OLTP and OLAP?
What are
ACID properties in SQL?
What is
normalization? Explain
1NF, 2NF, 3NF, and BCNF.
What is a
composite key?
What is a
surrogate key?
What is the use of the
COALESCE function?
What is the difference between
IS
NULL and IS NOT NULL?
What is
partitioning in SQL?
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Advanced SQL Interview Questions:
What are
window functions in SQL?
What is
CTE (Common Table Expression)?
What is the difference between
TEMP TABLE and CTE?
What is the difference between
RANK(), DENSE_RANK(), and ROW_NUMBER()?
What is a
materialized view?
What is the difference between
materialized views and normal views?
What is
sharding in SQL?
What is the
MERGE statement?
What is the
JSON data type in SQL?
What is
recursive CTE?
What is the
difference between LEFT JOIN and LEFT OUTER JOIN?
How does indexing impact performance?
What is the
difference between OLAP and OLTP?
What is
ETL (Extract, Transform, Load)?
What are
window functions? Explain
LEAD, LAG, and NTILE.
What is a
pivot table in SQL?
What is
Dynamic SQL?
What is a
NoSQL database? How is it different from SQL databases?
What is the
difference between SQL and PL/SQL?
How to find the
N-th highest salary in SQL?
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Practical SQL Queries:
Find the
second highest salary from an Employee table.
Find
duplicate records in a table.
Write a SQL query to find
the count of employees in each department.
Write a query to find
employees who earn more than their managers.
Write a query to
fetch the first three characters of a string.
Write a SQL query to
swap two columns in a table without using a temporary table.
Write a query to
find all employees who joined in the last 6 months.
Write a query to
find the most repeated values in a column.
Write a query to
delete duplicate rows from a table.
Write a SQL query to
find all customers who made more than 5 purchases.
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