SQL Programming Resources on Telegram: “🚀 SQL Roadmap 2026

🚀 SQL Roadmap 2026 — Part 2

SQL SELECT Statement & Retrieving Data

Now that you understand databases, tables, rows, columns, primary keys, and foreign keys, it's time to learn the most fundamental SQL command: SELECT.

Almost every SQL analysis starts with retrieving data.

1️⃣ What is SELECT?

SELECT is used to retrieve data from one or more columns in a table.

Basic syntax:

SELECT column_name
FROM table_name;

Example:

SELECT customer_name
FROM customers;

2️⃣ Select Multiple Columns

You can retrieve multiple columns by separating them with commas.

SELECT
    customer_id,
    customer_name,
    city
FROM customers;

SELECT *
FROM customers;

* means all columns.

⚠️ Interview Tip: Although SELECT * is convenient while exploring data, avoid relying on it in production queries. Prefer selecting only needed columns.

4️⃣ Column Aliases

Use AS to give a column a different name in the result.

SELECT
    customer_name AS name,
    city AS location
FROM customers;

The original table is not changed.

5️⃣ Aliases Without AS

SELECT
    customer_name name,
    city location
FROM customers;

However, using AS is generally clearer for beginners.

6️⃣ Calculations Inside SELECT

SELECT
    product_name,
    price,
    price * 0.90 AS discounted_price
FROM products;

7️⃣ Arithmetic Operators

+ Addition, - Subtraction, * Multiplication, / Division

SELECT
    product_name,
    selling_price,
    cost_price,
    selling_price - cost_price AS profit
FROM products;

8️⃣ Using Expressions

SELECT
    product_name,
    quantity,
    unit_price,
    quantity * unit_price AS total_value
FROM order_items;

9️⃣ DISTINCT

Removes duplicate values.

SELECT DISTINCT city
FROM customers;

🔟 DISTINCT Across Multiple Columns

SELECT DISTINCT
    city,
    customer_segment
FROM customers;

1️⃣1️⃣ Using SELECT With Text

SELECT
    customer_name,
    'Active Customer' AS status
FROM customers;

1️⃣2️⃣ Combining Columns

SELECT
    first_name,
    last_name,
    CONCAT(first_name, ' ', last_name) AS full_name
FROM employees;

1️⃣3️⃣ SELECT With a Condition

SELECT
    customer_name,
    city
FROM customers
WHERE city = 'Mumbai';

1️⃣5️⃣ SQL Query Structure

At this stage, learn this basic pattern:

SELECT column1, column2
FROM table_name;

SELECT column1, column2
FROM table_name
WHERE condition;

1️⃣6️⃣ A Real-World Example

Manager asks: "Show me product name, selling price, cost price, and profit"

SELECT
    product_name,
    selling_price,
    cost_price,
    selling_price - cost_price AS profit
FROM products;