FOREACH for array iteration in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to iterate over each element in the array using FOREACH.

PostgreSQL

DECLARE
  my_array integer[] := ARRAY[1, 2, 3];
  element integer;
BEGIN
  FOREACH element [1] ARRAY my_array LOOP
    RAISE NOTICE '%', element;
  END LOOP;
END;

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AFROM

BOF

CON

DIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using OF instead of IN causes a syntax error.

Using FROM or ON are not valid keywords here.

The correct syntax to iterate over an array in PostgreSQL using FOREACH is FOREACH element IN ARRAY my_array.

2fill in blank

medium

Complete the code to declare an array of text values.

PostgreSQL

DECLARE
  fruits text[] := [1];
BEGIN
  NULL;
END;

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AARRAY['apple', 'banana', 'cherry']

B['apple', 'banana', 'cherry']

C('apple', 'banana', 'cherry')

D{'apple', 'banana', 'cherry'}

Attempts:

3 left

💡 Hint

Common Mistakes

Using JSON-style [] notation causes errors.

Using parentheses () is for tuples, not arrays.

In PostgreSQL, arrays are declared using the ARRAY[...] syntax.

3fill in blank

hard

Fix the error in the FOREACH loop to correctly iterate over the array.

PostgreSQL

DECLARE
  nums integer[] := ARRAY[10, 20, 30];
  n integer;
BEGIN
  FOREACH n [1] nums LOOP
    RAISE NOTICE '%', n;
  END LOOP;
END;

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AIN ARRAY

BIN

CFROM ARRAY

DON ARRAY

Attempts:

3 left

💡 Hint

Common Mistakes

Using IN without ARRAY causes syntax errors.

Using ON ARRAY or FROM ARRAY are invalid.

The FOREACH loop requires the keyword IN ARRAY before the array variable to iterate correctly.

4fill in blank

hard

Fill both blanks to create a FOREACH loop that iterates over a text array and prints each fruit.

PostgreSQL

DECLARE
  fruits text[] := ARRAY['apple', 'banana', 'cherry'];
  fruit text;
BEGIN
  FOREACH fruit [1] [2] fruits LOOP
    RAISE NOTICE '%', fruit;
  END LOOP;
END;

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AOF

BIN

CARRAY

DTABLE

Attempts:

3 left

💡 Hint

Common Mistakes

Using OF instead of IN causes errors.

Using TABLE instead of ARRAY is invalid here.

The correct syntax is FOREACH fruit IN ARRAY fruits to iterate over the array.

5fill in blank

hard

Fill all three blanks to declare an integer array, iterate over it with FOREACH, and print each number.

PostgreSQL

DECLARE
  numbers [1] := [2];
  num integer;
BEGIN
  FOREACH num [3] numbers LOOP
    RAISE NOTICE '%', num;
  END LOOP;
END;

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Ainteger[]

BARRAY[5, 10, 15]

CIN ARRAY

Dtext[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using text[] instead of integer[] for numbers.

Not using IN ARRAY in FOREACH loop.

Incorrect array literal syntax.

We declare numbers as an integer array with integer[], assign it using ARRAY[5, 10, 15], and iterate using FOREACH num IN ARRAY numbers.