Which of the following SQL queries correctly uses a window function to calculate a running total of sales per employee?

easy📝 Syntax Q12 of 15

SQL - Window Functions Fundamentals

ASELECT employee_id, sale_amount, SUM(sale_amount) OVER (ORDER BY sale_date) AS running_total FROM sales GROUP BY employee_id;

BSELECT employee_id, sale_amount, SUM(sale_amount) GROUP BY employee_id ORDER BY sale_date AS running_total FROM sales;

CSELECT employee_id, sale_amount, SUM(sale_amount) FROM sales WINDOW (PARTITION BY employee_id ORDER BY sale_date) AS running_total;

DSELECT employee_id, sale_amount, SUM(sale_amount) OVER (PARTITION BY employee_id ORDER BY sale_date) AS running_total FROM sales;

Step-by-Step Solution

Solution:

Step 1: Identify correct window function syntax
SELECT employee_id, sale_amount, SUM(sale_amount) OVER (PARTITION BY employee_id ORDER BY sale_date) AS running_total FROM sales; uses SUM() OVER (PARTITION BY ... ORDER BY ...), which is the correct syntax for running totals per employee.
Step 2: Check other options for syntax errors
Options B, C, and D misuse GROUP BY or WINDOW clauses incorrectly, causing syntax errors or wrong logic.
Final Answer:
The correct query: SELECT employee_id, sale_amount, SUM(sale_amount) OVER (PARTITION BY employee_id ORDER BY sale_date) AS running_total FROM sales; -> Option D
Quick Check:
Window function syntax = SELECT employee_id, sale_amount, SUM(sale_amount) OVER (PARTITION BY employee_id ORDER BY sale_date) AS running_total FROM sales; [OK]

Quick Trick: Window functions use OVER(), GROUP BY does not [OK]

Common Mistakes:

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