MySQL OR Operator

The OR operator in MySQL is used to combine multiple conditions in a WHERE clause. It returns TRUE if any of the specified conditions are TRUE.

Syntax

SELECT column1, column2, ...
FROM table_name
WHERE condition1 OR condition2 OR ...;

1. Using OR with Multiple Conditions

Example

Retrieve employees who work in the "IT" department or earn a salary greater than 70,000.

SELECT id, name, department, salary
FROM employees
WHERE department = 'IT' OR salary > 70000;

Result

+----+-------+------------+--------+
| id | name  | department | salary |
+----+-------+------------+--------+
| 1  | Alice | IT         | 70000  |
| 2  | Bob   | IT         | 80000  |
| 3  | Eve   | HR         | 90000  |
+----+-------+------------+--------+

2. Combining OR with Other Operators

The OR operator can be used with comparison operators such as =, >, <, >=, <=, and <> (not equal).

Example

Get products priced below 100 or above 1,000:

SELECT product_id, product_name, price
FROM products
WHERE price < 100 OR price > 1000;

3. Using OR with Logical Operators

You can combine OR with AND or NOT for more complex conditions.

Example

Find customers from "New York" who have made purchases below 500 or are not VIP members:

SELECT customer_id, name, city, purchase_amount
FROM customers
WHERE city = 'New York' AND (purchase_amount < 500 OR is_vip = 0);

4. Practical Example

Sample Table: `orders`

+----+------------+-----------+--------+
| id | customer   | product   | amount |
+----+------------+-----------+--------+
| 1  | Alice      | Laptop    | 1500   |
| 2  | Bob        | Monitor   | 300    |
| 3  | Charlie    | Smartphone| 800    |
| 4  | Alice      | Tablet    | 400    |
+----+------------+-----------+--------+

Query: Get orders where the amount is greater than 1000 or the product is "Tablet":

SELECT id, customer, product, amount
FROM orders
WHERE amount > 1000 OR product = 'Tablet';

Result:

+----+----------+-----------+-------+
| id | customer | product   | amount|
+----+----------+-----------+-------+
| 1  | Alice    | Laptop    | 1500  |
| 4  | Alice    | Tablet    | 400   |
+----+----------+-----------+-------+

5. Using OR with Multiple Columns

You can use OR to evaluate conditions across multiple columns.

Example

Find employees who have "Manager" in their title or are in the "HR" department:

SELECT id, name, title, department
FROM employees
WHERE title LIKE '%Manager%' OR department = 'HR';

6. Common Errors

Operator Precedence: MySQL evaluates AND before OR. Use parentheses to specify precedence.

-- Without Parentheses
SELECT * FROM orders WHERE product = 'Laptop' OR amount > 500 AND customer = 'Alice';

-- With Parentheses
SELECT * FROM orders WHERE product = 'Laptop' OR (amount > 500 AND customer = 'Alice');

Missing Parentheses: Forgetting parentheses in complex conditions can lead to unexpected results.

7. Best Practices

Use Parentheses:
When combining OR with AND, always use parentheses to clarify precedence.

Avoid Overusing OR:
For better performance, consider using IN for multiple equality checks instead of multiple OR conditions.

-- Instead of this
SELECT * FROM employees WHERE department = 'IT' OR department = 'HR' OR department = 'Finance';

-- Use this
SELECT * FROM employees WHERE department IN ('IT', 'HR', 'Finance');

8. Performance Considerations

OR conditions can slow down queries when used excessively or without indexing.
Optimize queries by ensuring columns in OR conditions are indexed.

Let me know if you need more examples or further assistance!

Souy Soeng

MySQL OR Operator