String to array and array to string in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to convert a comma-separated string into an array.

PostgreSQL

SELECT string_to_array('apple,banana,cherry', [1]) AS fruits_array;

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

A';'

B'.'

C' '

D','

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong delimiter like ';' or '.' which won't split the string correctly.

The string_to_array function splits the string by the delimiter. Here, the delimiter is a comma ',' to separate the fruits.

2fill in blank

medium

Complete the code to join an array of strings into a single string separated by semicolons.

PostgreSQL

SELECT array_to_string(ARRAY['red', 'green', 'blue'], [1]) AS colors_string;

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 ';' which changes the output format.

The array_to_string function joins array elements using the specified delimiter. Here, ';' is used to separate colors.

3fill in blank

hard

Fix the error in the code to correctly convert a string to an array using a space as delimiter.

PostgreSQL

SELECT string_to_array('one two three', [1]) AS words_array;

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

A' '

B','

C';'

D''

Attempts:

3 left

💡 Hint

Common Mistakes

Using an empty string '' as delimiter which won't split the string correctly.

Using a comma ',' which does not split the string correctly.

To split the string by spaces, the delimiter must be a space character ' '.

4fill in blank

hard

Fill both blanks to convert a string to an array and then back to a string with a different delimiter.

PostgreSQL

SELECT array_to_string(string_to_array('cat|dog|bird', [1]), [2]) AS new_string;

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

A'|'

B','

C';'

D' '

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong delimiters that do not match the original string or desired output.

First, split the string by '|' to get the array. Then join the array elements with ';' to form the new string.

5fill in blank

hard

Fill all three blanks to create an array from a string, filter elements containing 'a', and join them with commas.

PostgreSQL

SELECT array_to_string(ARRAY(SELECT * FROM unnest(string_to_array('apple,banana,cherry,date', [1])) WHERE [2] LIKE '%a%'), [3]) AS filtered_string;

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

A','

Bunnest

D';'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong delimiters or missing unnest function causing errors.

Split the string by ',' to get the array. Use unnest to expand array elements. Filter elements containing 'a'. Join filtered elements with ','.