[Solved] You wrote this query:SELECT * FROM A RIGHT JOIN B ON A.id = B.idBut it returns NULLs in the A columns for every row. What could be a possible error? | SQL

SQL - LEFT and RIGHT JOIN

You wrote this query:
SELECT * FROM A RIGHT JOIN B ON A.id = B.id
But it returns NULLs in the A columns for every row. What could be a possible error?

AYou must use LEFT JOIN instead of RIGHT JOIN always.

BRIGHT JOIN syntax requires WHERE clause to work.

CRIGHT JOIN excludes all rows from the right table.

DThe ON condition uses wrong columns causing no matches.

Step-by-Step Solution

Solution:

Step 1: Check ON condition correctness
If ON uses wrong columns, matches fail and A columns are NULL for all rows.
Step 2: Understand RIGHT JOIN behavior
RIGHT JOIN always keeps all right table rows; all NULLs in A mean ON condition mismatch.
Final Answer:
The ON condition uses wrong columns causing no matches. -> Option D
Quick Check:
Wrong ON condition causes no matches = The ON condition uses wrong columns causing no matches. [OK]

Quick Trick: Check ON clause columns carefully for correct RIGHT JOIN results [OK]

Common Mistakes:

MISTAKES

Thinking RIGHT JOIN needs WHERE clause
Assuming RIGHT JOIN excludes right rows
Believing LEFT JOIN is always better

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More SQL Quizzes

You wrote this query:

Step 1: Check ON condition correctness

Step 2: Understand RIGHT JOIN behavior

Final Answer:

Quick Check:

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