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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
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Explain INNER, LEFT, RIGHT and FULL JOIN.
Junior
#Join
#Query
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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
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How do INSERT, UPDATE and DELETE work?
Junior
#Query
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How do you handle duplicates with DISTINCT?
Junior
#Query
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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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How does the CASE expression work?
Middle
#Query
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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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