SQL - Subqueries
Which of the following is the correct syntax to use a subquery in the
WHERE clause to find employees in departments with ID 10 or 20?Which of the following is the correct syntax to use a subquery in the WHERE clause to find employees in departments with ID 10 or 20?
easy📝 Syntax Q12 of 15
Step-by-Step Solution
Solution:
Step 1: Identify correct subquery syntax with IN
The subquery must be enclosed in parentheses and used with IN to match multiple values.Step 2: Check each option's syntax
SELECT * FROM employees WHERE department_id IN (SELECT department_id FROM departments WHERE department_id IN (10, 20)); correctly uses IN with a subquery in parentheses. SELECT * FROM employees WHERE department_id = (SELECT department_id FROM departments WHERE department_id IN (10, 20)); uses = which expects one value, causing error. SELECT * FROM employees WHERE department_id IN SELECT department_id FROM departments WHERE department_id IN (10, 20); misses parentheses around subquery. SELECT * FROM employees WHERE department_id IN (SELECT department_id FROM departments WHERE department_id = 10 OR 20); has incorrect WHERE clause syntax.Final Answer:
SELECT * FROM employees WHERE department_id IN (SELECT department_id FROM departments WHERE department_id IN (10, 20)); -> Option DQuick Check:
Subquery with IN needs parentheses [OK]
Quick Trick: Use IN with parentheses for subqueries returning multiple values [OK]
Common Mistakes:
MISTAKES- Using = instead of IN for multiple values
- Omitting parentheses around subquery
- Incorrect WHERE clause conditions inside subquery
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