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SQL
Database
SQL
Relational database querying: joins, indexes and transactions.
30
questions
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Junior
10
Middle
12
Senior
8
SQL questions
30 / 30 shown
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Newest
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Explain INNER, LEFT, RIGHT and FULL JOIN.
Junior
#Join
#Query
Details →
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What is an index in SQL? When should and shouldn't you use one?
Middle
#Index
#Performance
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What is SQL and what is it used for?
Junior
#Database
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How does the SELECT statement work?
Junior
#Query
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How do you filter rows with WHERE?
Junior
#Query
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What are aggregate functions (COUNT, SUM, AVG, etc.)?
Junior
#Query
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How do GROUP BY and HAVING work?
Junior
#Query
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How do ORDER BY and LIMIT work, and how do you paginate?
Junior
#Query
Details →
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How do INSERT, UPDATE and DELETE work?
Junior
#Query
Details →
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How do you handle duplicates with DISTINCT?
Junior
#Query
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How does NULL behave in SQL?
Junior
#Database
Details →
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What are subqueries and how do you use them?
Middle
#Query
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What are UNION, INTERSECT and EXCEPT?
Middle
#Query
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What are primary keys and foreign keys?
Middle
#Database
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What database constraints are there?
Middle
#Database
Details →
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What is database normalization?
Middle
#Database
Details →
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What are transactions and ACID properties?
Middle
#Database
Details →
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What are views and materialized views?
Middle
#Database
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How does the CASE expression work?
Middle
#Query
Details →
›
What are common string and date functions?
Middle
#Query
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What is a self-join?
Middle
#Query
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What are window functions?
Senior
#Query
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What are Common Table Expressions (CTEs)?
Senior
#Query
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How do you optimize slow SQL queries?
Senior
#Performance
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What are transaction isolation levels?
Senior
#Database
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What causes deadlocks and how do you prevent them?
Senior
#Database
Details →
›
What are stored procedures and when should you use them?
Senior
#Database
Details →
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What are DDL, DML, DCL and TCL?
Senior
#Database
Details →
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What are common SQL data types and how do you choose them?
Middle
#Database
Details →
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What is table partitioning?
Senior
#Performance
Details →
