[Solved] Consider this PL/pgSQL snippet:DECLARE table_name text := 'users'; rec_count int;... END;What will this function return when called if the users table has 10 rows? | PostgreSQL

PostgreSQL - Advanced PL/pgSQL

Consider this PL/pgSQL snippet:

DECLARE
  table_name text := 'users';
  rec_count int;
BEGIN
  EXECUTE 'SELECT count(*) FROM ' || table_name INTO rec_count;
  RETURN rec_count;
END;

What will this function return when called if the users table has 10 rows?

ANULL

BAn error because of missing quotes

C0

D10

Step-by-Step Solution

Solution:

Step 1: Understand dynamic SQL concatenation
The query string becomes 'SELECT count(*) FROM users', which is valid SQL.
Step 2: EXECUTE runs the query and stores result
EXECUTE runs the query and puts the count into rec_count variable.
Final Answer:
10 -> Option D
Quick Check:
Count rows in users = 10 [OK]

Quick Trick: Concatenate table name safely, EXECUTE runs query, INTO stores result [OK]

Common Mistakes:

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Consider this PL/pgSQL snippet: