Why optimization prevents slow queries in Supabase - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from the users table.

Supabase

SELECT [1] FROM users;

Drag options to blanks, or click blank then click option'

A*

Bid

Cemail

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting only one column when all are needed.

Using column names without quotes.

The asterisk (*) selects all columns from the table, which is the simplest way to retrieve all data.

2fill in blank

medium

Complete the code to filter users with age greater than 30.

Supabase

SELECT * FROM users WHERE age [1] 30;

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A<=

B=

C<

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' which filters for ages less than 30.

Using '=' which filters for age exactly 30.

The '>' operator filters rows where age is greater than 30, which matches the requirement.

3fill in blank

hard

Fix the error in the query to count users grouped by country.

Supabase

SELECT country, COUNT(*) [1] users GROUP BY country;

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AIN

BON

CFROM

DWHERE

Attempts:

3 left

💡 Hint

Common Mistakes

Using WHERE instead of FROM causes syntax errors.

Using ON or IN in place of FROM is incorrect here.

The FROM keyword specifies the table to select data from, which is required before GROUP BY.

4fill in blank

hard

Fill both blanks to optimize the query by indexing the age column and filtering efficiently.

Supabase

CREATE INDEX [1] ON users([2]);

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Aidx_users_age

Bage

Cname

Demail

Attempts:

3 left

💡 Hint

Common Mistakes

Indexing columns not used in filters does not improve query speed.

Using invalid index names causes errors.

Creating an index named 'idx_users_age' on the 'age' column speeds up queries filtering by age.

5fill in blank

hard

Fill all three blanks to write a query that selects user names, filters by age greater than 25, and orders results by name ascending.

Supabase

SELECT [1] FROM users WHERE age [2] 25 ORDER BY [3] ASC;

Drag options to blanks, or click blank then click option'

Aname

B>

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Ordering by age instead of name changes the output order.

Using '<' instead of '>' filters the wrong age group.

Selecting 'name', filtering with '>' for age, and ordering by 'name' ascending produces the desired result efficiently.