[Solved] Why does this query cause an error?SELECT u.id, o.amount FROM users u, LATERAL (SELECT amount FROM orders WHERE user_id = u.id) o WHERE o.amount > 100; | PostgreSQL

PostgreSQL - Subqueries in PostgreSQL

Why does this query cause an error?

SELECT u.id, o.amount FROM users u, LATERAL (SELECT amount FROM orders WHERE user_id = u.id) o WHERE o.amount > 100;

AFiltering on LATERAL subquery column in WHERE causes error

BLATERAL cannot be used with comma joins

CSubquery must be aliased differently

DNo error, query is valid

Step-by-Step Solution

Solution:

Step 1: Understand WHERE filtering on LATERAL
Filtering on a column from LATERAL subquery in WHERE clause can cause errors if subquery returns no rows (NULL).
Step 2: Analyze the error cause
Because LATERAL subquery may return no rows, filtering in WHERE excludes those rows, causing unexpected behavior or error.
Final Answer:
Filtering on LATERAL subquery column in WHERE causes error -> Option A
Quick Check:
Filter on LATERAL output in WHERE can cause errors [OK]

Quick Trick: Filter LATERAL results in JOIN ON, not WHERE [OK]

Common Mistakes:

Using WHERE to filter LATERAL subquery columns
Thinking LATERAL disallows comma joins
Confusing aliasing rules

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Why does this query cause an error?

Step 1: Understand WHERE filtering on LATERAL

Step 2: Analyze the error cause

Final Answer:

Quick Check:

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