Quiz, SQL basics

Answer all ten questions, then press Check my answers. You need 70% to pass. If you do not pass, read the explanations and try again.

Question 1 of 10

Which query gives the title column of every row in books?

SELECT title FROM books;FROM books SELECT title;GET title FROM books;SELECT books.title;

Question 2 of 10

Which WHERE clause finds the books of the genre Mystery?

WHERE genre == "Mystery"WHERE genre = 'Mystery'WHERE genre = MysteryWHERE genre IS 'Mystery' and nothing else

Question 3 of 10

Which pattern matches every title that ends with ing?

LIKE 'ing%'LIKE '%ing'LIKE '_ing'LIKE '*ing'

Question 4 of 10

What does this query return?

SELECT title FROM books ORDER BY price DESC LIMIT 2;

The two cheapest titles.The two most expensive titles, the most expensive first.All titles, sorted by price, with two columns.Two random titles.

Question 5 of 10

What does COUNT(*) give?

The sum of all values.The number of rows.The number of columns.The largest value.

Question 6 of 10

What is the difference between WHERE and HAVING?

WHERE filters rows before they are grouped. HAVING filters groups after they are made.WHERE filters groups. HAVING filters rows.They are the same. You can use either one.HAVING can only be used with ORDER BY.

Question 7 of 10

You run SELECT genre, COUNT(*) FROM books GROUP BY genre; on a table with 4 genres. How many rows are in the result?

14The number of booksIt stops with an error.

Question 8 of 10

A customer has no orders. Which join keeps this customer in the result, with NULL in the order columns?

JOINLEFT JOIN, with customers as the first tableINNER JOINORDER BY

Question 9 of 10

What happens if you run DELETE FROM books; with no WHERE clause?

Nothing. SQL asks for a WHERE clause.It deletes only the first row.It deletes every row of the table.It deletes the table, and its columns.

Question 10 of 10

Which statements about a subquery are true? Choose all that apply.

Choose all answers that apply.

It is a SELECT inside another query, in parentheses.The database runs the inner query first.It can be used with IN to compare a value to a list.It can only give one row.

Answer every question to check.