VARIADIC parameters in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function that accepts a variadic integer array parameter.

PostgreSQL

CREATE FUNCTION sum_numbers([1] integer[]) RETURNS integer AS $$ BEGIN RETURN 0; END; $$ LANGUAGE plpgsql;

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Anumbers VARIADIC

Bnumbers

CVARIADIC numbers

DVARIADIC

Attempts:

3 left

💡 Hint

Common Mistakes

Placing VARIADIC after the parameter name.

Omitting the VARIADIC keyword.

Using VARIADIC without a parameter name.

In PostgreSQL, to declare a variadic parameter, you write VARIADIC before the parameter name and type, like VARIADIC numbers integer[].

2fill in blank

medium

Complete the function call to pass multiple integers as a variadic argument.

PostgreSQL

SELECT sum_numbers([1]);

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AVARIADIC ARRAY[1, 2, 3]

BARRAY[1, 2, 3]

C1, 2, 3

DVARIADIC 1, 2, 3

Attempts:

3 left

💡 Hint

Common Mistakes

Passing values without VARIADIC keyword.

Passing values separated by commas without ARRAY.

Using VARIADIC without ARRAY.

When calling a function with a variadic parameter, you use VARIADIC ARRAY[...] to pass multiple values as one array.

3fill in blank

hard

Fix the error in the function definition to correctly use a variadic text parameter.

PostgreSQL

CREATE FUNCTION concat_texts([1] text) RETURNS text AS $$ BEGIN RETURN ''; END; $$ LANGUAGE plpgsql;

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AVARIADIC texts

BVARIADIC texts text[]

Ctexts VARIADIC

Dtexts text VARIADIC

Attempts:

3 left

💡 Hint

Common Mistakes

Placing VARIADIC after the parameter name.

Using text[] instead of text as type.

Omitting VARIADIC keyword.

The correct syntax is VARIADIC texts text to declare a variadic parameter of type text.

4fill in blank

hard

Fill both blanks to create a function that sums variadic integers and returns the total.

PostgreSQL

CREATE FUNCTION sum_all([1] integer) RETURNS integer AS $$ DECLARE total integer := 0; BEGIN FOREACH num IN ARRAY [2] LOOP total := total + num; END LOOP; RETURN total; END; $$ LANGUAGE plpgsql;

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AVARIADIC nums

Bnums

Attempts:

3 left

💡 Hint

Common Mistakes

Not using VARIADIC in the parameter.

Looping over the wrong variable name.

Using the parameter as a scalar instead of an array.

The function parameter must be declared as VARIADIC nums integer (here VARIADIC nums is the blank), and inside the function, you loop over nums which is the array of integers.

5fill in blank

hard

Fill all three blanks to define and call a variadic function that concatenates texts with a separator.

PostgreSQL

CREATE FUNCTION concat_with_sep([1] text, [2] text) RETURNS text AS $$ BEGIN RETURN array_to_string([3], sep); END; $$ LANGUAGE plpgsql; SELECT concat_with_sep(',', VARIADIC ARRAY['a', 'b', 'c']);

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Asep

BVARIADIC texts

Ctexts

Dtexts[]

Attempts:

3 left

💡 Hint

Common Mistakes

Not using VARIADIC for the second parameter.

Using the wrong variable name inside the function.

Declaring the separator as variadic.

The first parameter is the separator sep, the second is the variadic parameter VARIADIC texts, and inside the function, you use texts as the array to join.