Solution:Step 1: Understand function behaviorThe function takes a VARIADIC text array and concatenates elements with '-' using array_to_string.Step 2: Analyze the callCalling join_words('red', 'green', 'blue') passes three text arguments as an array {'red','green','blue'}.Step 3: ResultThe function

[Solved] Given the function:CREATE FUNCTION join_words(VARIADIC words text[]) RETURNS text AS $ SELECT... $ LANGUAGE sql;What is the result of SELECT join_words('red', 'green', 'blue');? | PostgreSQL

PostgreSQL - Advanced PL/pgSQL

Given the function:

CREATE FUNCTION join_words(VARIADIC words text[]) RETURNS text AS $$
  SELECT array_to_string(words, '-');
$$ LANGUAGE sql;

What is the result of SELECT join_words('red', 'green', 'blue');?

A'red-green-blue'

B'{red,green,blue}'

C'red,green,blue'

DError: wrong input type

Step-by-Step Solution

Solution:

Step 1: Understand function behavior
The function takes a VARIADIC text array and concatenates elements with '-' using array_to_string.
Step 2: Analyze the call
Calling join_words('red', 'green', 'blue') passes three text arguments as an array {'red','green','blue'}.
Step 3: Result
The function returns the string 'red-green-blue'.
Final Answer:
'red-green-blue' -> Option A
Quick Check:
VARIADIC packs arguments into array, then joined with '-' [OK]

Quick Trick: VARIADIC packs args into array [OK]

Common Mistakes:

Expecting array literal output
Confusing array_to_string with string_agg
Assuming error due to multiple arguments

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Given the function:

Step 1: Understand function behavior

Step 2: Analyze the call

Step 3: Result

Final Answer:

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