[Solved] What will happen when the following PL/pgSQL block is executed?DECLARE col_name text := 'salary'; total numeric; BEGIN EXECUTE 'SELECT sum(' || col_name || ') FROM employees' INTO total;... | PostgreSQL

PostgreSQL - Advanced PL/pgSQL

What will happen when the following PL/pgSQL block is executed?

DECLARE
  col_name text := 'salary';
  total numeric;
BEGIN
  EXECUTE 'SELECT sum(' || col_name || ') FROM employees' INTO total;
  RAISE NOTICE 'Total salary: %', total;
END;

AIt causes a syntax error due to string concatenation

BIt raises a runtime error because sum() cannot be used dynamically

CIt prints the column name instead of sum

DIt calculates and prints the sum of the salary column

Step-by-Step Solution

Solution:

Step 1: Understand dynamic query construction
The query string concatenates the column name correctly to form a valid SQL sum query.
Step 2: EXECUTE runs the query and INTO stores the result
The sum is calculated and stored in total, then printed.
Final Answer:
It calculates and prints the sum of the salary column -> Option D
Quick Check:
Dynamic SQL with concatenation works for column names [OK]

Quick Trick: Concatenate strings to build dynamic queries safely [OK]

Common Mistakes:

Assuming string concatenation causes syntax errors
Believing sum() cannot be used dynamically
Forgetting to use INTO to capture results

Master "Advanced PL/pgSQL" in PostgreSQL

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

What will happen when the following PL/pgSQL block is executed?

Step 1: Understand dynamic query construction

Step 2: EXECUTE runs the query and INTO stores the result

Final Answer:

Quick Check:

Want More Practice?