String aggregation with STRING_AGG in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to aggregate names into a single string separated by commas.

PostgreSQL

SELECT STRING_AGG(name, [1]) AS all_names FROM users;

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

A','

B' '

C';'

D'.'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a semicolon ';' which is not a common separator in lists.

Forgetting to put the separator inside quotes.

Using a period '.' which is uncommon for separating names.

The STRING_AGG function concatenates strings using the specified separator. Here, a comma ',' is used to separate names.

2fill in blank

medium

Complete the code to aggregate emails separated by a semicolon.

PostgreSQL

SELECT STRING_AGG(email, [1]) AS all_emails FROM contacts;

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

A'|'

B','

C':'

D';'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a comma ',' instead of a semicolon.

Not quoting the separator character.

Using a colon ':' which is not the requested separator.

Using ';' as the separator aggregates emails separated by semicolons.

3fill in blank

hard

Fix the error in the code to aggregate product names separated by a space.

PostgreSQL

SELECT STRING_AGG(product_name [1] ' ') AS products FROM inventory;

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

A;

B,

C(

D)

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the comma between arguments.

Using a semicolon instead of a comma.

Using parentheses incorrectly.

The STRING_AGG function requires a comma between the column and the separator string.

4fill in blank

hard

Fill both blanks to aggregate city names separated by a dash and order them alphabetically.

PostgreSQL

SELECT STRING_AGG(city, [1] ORDER BY [2]) AS cities FROM locations;

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

A'-'

Bcity

Cname

D'_'

Attempts:

3 left

💡 Hint

Common Mistakes

Using an underscore '_' instead of a dash.

Ordering by a non-existent column like 'name'.

Forgetting to quote the separator.

The separator is a dash '-' and the ORDER BY uses the city column to sort names alphabetically.

5fill in blank

hard

Fill all three blanks to aggregate usernames in uppercase, separated by a colon, ordered by user ID.

PostgreSQL

SELECT STRING_AGG(UPPER([1]), [2] ORDER BY [3]) AS user_list FROM users;

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

Ausername

B':'

Cuser_id

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'name' instead of 'username' or 'user_id'.

Forgetting to quote the separator.

Not using the correct column for ordering.

We convert 'username' to uppercase, separate by colon ':', and order by 'user_id'.