Play Store Application link – SQL in 18 steps – App on Google Play
Introduction
SQL Operators help in performing calculations, filtering data, and making comparisons. Think of them as tools that refine search results, just like using filters while shopping online!
1. Arithmetic Operators – Performing Calculations
These operators help in performing basic math calculations.
| Operator | Description | Example |
|---|---|---|
+ | Addition | SELECT 10 + 5; → 15 |
- | Subtraction | SELECT 10 - 5; → 5 |
* | Multiplication | SELECT 10 * 5; → 50 |
/ | Division | SELECT 10 / 5; → 2 |
% | Modulus (Remainder) | SELECT 10 % 3; → 1 |
Example: Calculate Total Price in Orders Table
SELECT product_name, quantity, price, quantity * price AS total_price
FROM Orders;
2. Comparison Operators – Filtering Data
These operators help compare values.
| Operator | Meaning |
|---|---|
= | Equal to |
!= or <> | Not equal to |
< | Less than |
> | Greater than |
<= | Less than or equal to |
>= | Greater than or equal to |
Example: Find Students Aged 18 and Above
SELECT * FROM Students WHERE age >= 18;
Example: Find Products That Are Not Laptops
SELECT * FROM Products WHERE category != 'Laptop';
3. Logical Operators – Combining Conditions
Logical operators help in applying multiple conditions.
| Operator | Description |
|---|---|
AND | Both conditions must be true |
OR | At least one condition must be true |
NOT | Negates a condition |
Example: Find Employees Aged 25-35 with Salary Above 50,000
SELECT * FROM Employees WHERE age BETWEEN 25 AND 35 AND salary > 50000;
Example: Find Orders That Are Not Delivered
SELECT * FROM Orders WHERE NOT status = 'Delivered';
4. Wildcard Operators – Searching Patterns
Used with LIKE to find partial matches.
| Wildcard | Meaning |
|---|---|
% | Represents zero or more characters |
_ | Represents a single character |
Example: Find Names Starting with ‘A’
SELECT * FROM Customers WHERE name LIKE 'A%';
Example: Find 5-Letter Names Starting with ‘J’
SELECT * FROM Customers WHERE name LIKE 'J____';
5. IN, BETWEEN, and EXISTS – Advanced Filtering
Using IN – Match Multiple Values
Find employees from specific departments:
SELECT * FROM Employees WHERE department IN ('HR', 'Finance', 'IT');
Using BETWEEN – Find Values in a Range
Find products priced between 500 and 1000:
SELECT * FROM Products WHERE price BETWEEN 500 AND 1000;
Using EXISTS – Check If Related Data Exists
Find customers who have placed orders:
SELECT * FROM Customers WHERE EXISTS (SELECT 1 FROM Orders WHERE Orders.customer_id = Customers.customer_id);
Conclusion
SQL operators help in refining queries, making searches efficient, and performing calculations. Mastering them ensures effective database interactions.