Solution:Step 1: Understand NATURAL JOIN behaviorNATURAL JOIN uses all columns with the same name as join keys automatically.Step 2: Identify cause of unexpected resultsIf multiple columns share the same name, the join condition may include unintended columns, causing unexpected output.Final Answer:

[Solved] You wrote:SELECT * FROM orders NATURAL JOIN customers;But the query returns unexpected results. What is a likely cause? | PostgreSQL

PostgreSQL - Joins in PostgreSQL

You wrote:
SELECT * FROM orders NATURAL JOIN customers;
But the query returns unexpected results. What is a likely cause?

AYou forgot to add an ON clause.

BThe tables have multiple columns with the same name, causing unintended join keys.

CNATURAL JOIN does not work with SELECT *.

DThe tables have no columns with the same name.

Step-by-Step Solution

Solution:

Step 1: Understand NATURAL JOIN behavior
NATURAL JOIN uses all columns with the same name as join keys automatically.
Step 2: Identify cause of unexpected results
If multiple columns share the same name, the join condition may include unintended columns, causing unexpected output.
Final Answer:
The tables have multiple columns with the same name, causing unintended join keys. -> Option B
Quick Check:
Unexpected results = multiple same-named columns [OK]

Quick Trick: Multiple same-named columns cause unexpected NATURAL JOIN keys [OK]

Common Mistakes:

Thinking NATURAL JOIN needs ON clause
Believing SELECT * affects NATURAL JOIN behavior
Assuming no same-named columns means no join

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You wrote:

Step 1: Understand NATURAL JOIN behavior

Step 2: Identify cause of unexpected results

Final Answer:

Quick Check:

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