SELECT Clause in SQL

Last Updated: 7th January 2026

The SELECT clause is used to choose which columns you want to retrieve from a table. It is the starting point of every DQL query.

  • SELECT tells the database what data to return
  • It does not decide the table (that is handled by FROM)
  • It works only for reading data

Hinglish Tip 🗣: > SELECT ka matlab hai — database se kya-kya data chahiye, ye batana.

🧾 Basic Syntax of SELECT

SELECT column_name;

⚠️ This syntax alone is incomplete. In real queries, it is always used with other clauses, but here we focus only on SELECT behavior.

📂 Selecting All Columns

To select all columns from a table, use * (asterisk).

SELECT *;

Meaning:

  • * → all available columns

📄 Selecting Specific Columns

You can select only required columns by listing them.

SELECT name, marks;

Benefits:

  • Less data transfer
  • Better readability
  • Faster queries

🔁 Column Order Matters in SELECT

The order of columns in SELECT decides the order of output, not the table structure.

SELECT marks, name;

Output columns will appear as:

  1. marks
  2. name

✏ Using Aliases in SELECT

Aliases are temporary names given to columns in the result.

SELECT name AS student_name, marks AS score;

Why aliases are used:

  • Improve readability
  • Useful in reports
  • Helpful with calculations

🧮 SELECT with Expressions

SELECT can also perform calculations.

SELECT marks + 5;

Example use cases:

  • Adding bonus marks
  • Calculating tax
  • Showing derived values

🔍 SELECT with DISTINCT

DISTINCT removes duplicate values from the result.

SELECT DISTINCT department;

✔ Returns only unique values

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