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20
Total Questions
8
easy
9
intermediate
3
advanced
0
expert
What's Covered in This Guide
1
SQL Fundamentals
7 questions
2
Advanced Queries
5 questions
3
Query Optimization
3 questions
4
Database Design
5 questions
Filter:
All Levels
Easy
Intermediate
Advanced
Expert
Question Categories
SQL Fundamentals
7
Advanced Queries
5
Query Optimization
3
Database Design
5
SQL Fundamentals
7 questions
1
What is the difference between WHERE and HAVING clauses?
Easy
2-3 min
Filtering
where
having
filtering
2
Explain the different types of JOINs in SQL.
Easy
3-4 min
Joins
joins
inner
outer
cross
3
What is the difference between UNION and UNION ALL?
Easy
2-3 min
Set Operations
union
set-operations
4
What are NULL values and how do you handle them?
Easy
3-4 min
NULL Handling
null
coalesce
handling
5
What is the difference between DELETE, TRUNCATE, and DROP?
Easy
2-3 min
DDL/DML
delete
truncate
drop
ddl
6
How do you remove duplicate rows from a table?
Intermediate
4-5 min
Data Cleaning
duplicates
distinct
row_number
7
Explain GROUP BY and aggregate functions.
Easy
3-4 min
Aggregation
group-by
aggregates
sum
count
Advanced Queries
5 questions
8
Explain window functions and when to use them.
Advanced
5-6 min
Window Functions
window
over
partition
ranking
9
How do you write and optimize subqueries?
Intermediate
4-5 min
Subqueries
subquery
correlated
exists
in
10
What are Common Table Expressions (CTEs)?
Intermediate
4-5 min
CTEs
cte
with
recursive
11
How do you handle dates and times in SQL?
Intermediate
4-5 min
Date/Time
dates
datetime
timestamp
12
How do you use CASE expressions effectively?
Intermediate
3-4 min
Conditional Logic
case
conditional
when
Query Optimization
3 questions
13
How do indexes work and when should you use them?
Intermediate
5-6 min
Indexing
index
btree
performance
14
How do you read and use EXPLAIN plans?
Advanced
5-6 min
Query Optimization
explain
query-plan
optimization
15
What are common query performance anti-patterns?
Intermediate
5-6 min
Query Optimization
performance
anti-patterns
optimization
Database Design
5 questions
16
What is database normalization?
Intermediate
4-5 min
Database Design
normalization
normal-forms
design
17
How do you design a many-to-many relationship?
Easy
3-4 min
Database Design
relationships
junction-table
design
18
What are ACID properties in database transactions?
Intermediate
4-5 min
Transactions
acid
transactions
consistency
19
How do you handle hierarchical data in SQL?
Advanced
5-6 min
Database Design
hierarchy
tree
recursive
20
What are the differences between primary key, unique key, and foreign key?
Easy
3-4 min
Constraints
keys
constraints
relationships