[Solved] Find the error in this query:SELECT emp_id FROM Employees WHERE dept_id IN (SELECT dept_name FROM Departments); | SQL

SQL - Subqueries

Find the error in this query:

SELECT emp_id FROM Employees WHERE dept_id IN (SELECT dept_name FROM Departments);

Aemp_id is not a valid column

BMissing WHERE clause in subquery

CIN operator cannot be used with subqueries

DSubquery returns dept_name but main query compares dept_id

Step-by-Step Solution

Solution:

Step 1: Compare columns in main query and subquery
Main query filters dept_id, but subquery returns dept_name, causing mismatch.
Step 2: Identify type mismatch
dept_id and dept_name are different types; comparison is invalid.
Final Answer:
Subquery returns dept_name but main query compares dept_id -> Option D
Quick Check:
Column types must match in IN subquery [OK]

Quick Trick: Ensure subquery returns same type as main query column [OK]

Common Mistakes:

MISTAKES

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