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PostgreSQL IN

The IN operator checks if a given value matches any value in a list or subquery. It’s more concise and often faster than multiple OR conditions.

Key Topics

1. Basic Usage

SELECT first_name, department
FROM employees
WHERE department IN ('Sales', 'Marketing', 'HR');

This returns rows where department is Sales, Marketing, or HR.

2. Using Subqueries

SELECT first_name, department
FROM employees
WHERE department IN (SELECT dept_name FROM departments WHERE location = 'NY');

The subquery returns valid departments in NY, and employees matching those departments are retrieved.

Best Practices

  • Use IN for cleaner queries compared to multiple OR statements.
  • Optimize subqueries with indexes to enhance performance.

Key Takeaways

  • IN provides a concise way to match a value against multiple options.
  • Subqueries with IN can dynamically filter based on another table's results.
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