UUID type and generation in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a table with a UUID primary key column.

PostgreSQL

CREATE TABLE users (id [1] PRIMARY KEY);

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AUUID

BINT

CTEXT

DSERIAL

Attempts:

3 left

💡 Hint

Common Mistakes

Using INT or SERIAL instead of UUID for unique IDs.

The UUID type stores universally unique identifiers, perfect for unique keys.

2fill in blank

medium

Complete the code to generate a random UUID value.

PostgreSQL

SELECT [1]();

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Arandom_uuid

Buuid_generate_v4

Cuuid_generate_v1

Dgen_random_uuid

Attempts:

3 left

💡 Hint

Common Mistakes

Using uuid_generate_v1() which generates time-based UUIDs.

gen_random_uuid() generates a random UUID (version 4) in PostgreSQL.

3fill in blank

hard

Fix the error in the code to insert a new row with a generated UUID.

PostgreSQL

INSERT INTO orders (order_id) VALUES ([1]());

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

Agen_random_uuid

Buuid_generate_v4

Cuuid_generate_v2

Drandom

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent functions like uuid_generate_v2() or random().

gen_random_uuid() is the correct function to generate a random UUID for insertion.

4fill in blank

hard

Fill both blanks to create a table with a UUID primary key that defaults to a generated UUID.

PostgreSQL

CREATE TABLE sessions (session_id [1] PRIMARY KEY DEFAULT [2]());

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AUUID

BTEXT

Cgen_random_uuid

Duuid_generate_v4

Attempts:

3 left

💡 Hint

Common Mistakes

Using TEXT type or wrong default functions for UUID columns.

The session_id column should be of type UUID and default to gen_random_uuid() to auto-generate unique IDs.

5fill in blank

hard

Fill all three blanks to select UUIDs from a table where the UUID is not null and order by UUID.

PostgreSQL

SELECT [1] FROM devices WHERE [2] IS NOT NULL ORDER BY [3];

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Adevice_id

Buuid

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing different column names or using columns that don't exist.

We select the device_id column, filter where it is not null, and order by the same column.