Practice Subqueries And Nested Queries (19.1.1) - Advanced SQL and NoSQL for Data Science

Practice: Subqueries and Nested Queries

Lesson 19.1.1Advanced SQL and NoSQL for Data Science

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10 questions

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4 cards from this section. Quick, good the night before a test.
Exercise
6 questions · about 4 min · pass mark 70%. Hints available.
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Quiz
4 questions · about 3 min · pass mark 70%. Hints available.
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6 sample questions

Question 1.
What is the purpose of a subquery in SQL?
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Think about how one query can feed into another.
Question 2.
Can subqueries be used in the WHERE clause?
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Consider how we restrict results based on another dataset.
3Question 3.
What is a subquery?
- A query that joins tables
- A query within another query
- A query that deletes data
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Recall how one query can influence another.
4Question 4.
Subqueries can be used in which SQL clauses?
- SELECT
- WHERE
- FROM
- All of the above
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Think of all the places we've mentioned using them.
Question 5.
Create a SQL query that retrieves the names of employees who earn more than the average salary of their specific department, using subqueries.
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Think about how to correlate the subquery with the outer query logically.
Question 6.
Explain under what circumstances you would prefer using a JOIN over a subquery and provide an example.
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Consider the relationships between tables and how to express them directly.

6 more questions in this section. Enroll free to practise them all.