[Solved] Why does this query cause an error?SELECT customer_id, order_date, COUNT(*) FROM orders GROUP BY customer_id; | SQL

SQL - GROUP BY and HAVING

Why does this query cause an error?

SELECT customer_id, order_date, COUNT(*) FROM orders GROUP BY customer_id;

AGROUP BY must include all columns in SELECT

Bcustomer_id cannot be grouped

Corder_date is neither grouped nor aggregated

DCOUNT(*) cannot be used with GROUP BY

Step-by-Step Solution

Solution:

Step 1: Review SELECT and GROUP BY columns
Columns in SELECT must be grouped or aggregated when GROUP BY is used.
Step 2: Identify problem
order_date is selected but not grouped or aggregated, causing an error.
Final Answer:
order_date is neither grouped nor aggregated -> Option C
Quick Check:
Non-aggregated column error = D [OK]

Quick Trick: Non-grouped columns must be aggregated [OK]

Common Mistakes:

MISTAKES

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