Chapter 2: SQL Syntax Basics

SQL Syntax Basics

Alright, class! Welcome to Chapter 2 — the place where we stop talking about SQL and actually start speaking it. Think of this as learning the grammar and pronunciation of a new language. If you get these basics right, everything else in SQL will feel much easier and natural.

Today we’re going to cover four super-important foundational things:

• The basic structure of SQL statements
• How to write comments (so you can explain your code to yourself and others)
• Case sensitivity (does uppercase/lowercase matter?)
• Semicolon usage (when and why you need that little ; at the end)

I’m going to explain everything like we’re sitting together in a Mumbai café, with me drawing on a napkin and showing you real examples. Let’s go step by step!

1. Basic Structure of SQL Statements

Every SQL statement follows a very predictable pattern. It’s almost like filling in a template. Most statements have these parts:

Here are the most common types of SQL statements you’ll write:

• SELECT (to read data) Most common statement in the world!
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  SELECT column1, column2, column3 FROM table_name WHERE condition ORDER BY column_name LIMIT 10;

• INSERT (to add new data)
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  INSERT INTO table_name (column1, column2) VALUES ('value1', 'value2');

• UPDATE (to change existing data)
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  UPDATE table_name SET column1 = 'new_value' WHERE condition;

• DELETE (to remove data)
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  DELETE FROM table_name WHERE condition;

• CREATE (to make new tables, databases, etc.)
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  CREATE TABLE employees (     id INT PRIMARY KEY,     name VARCHAR(100),     salary DECIMAL(10,2) );

Golden Rules for Structure:

• Keywords like SELECT, FROM, WHERE, INSERT, UPDATE, etc. are written in uppercase by convention (though not required).
• You can write the entire query on one line or spread it over multiple lines — the database doesn’t care.
• Indentation and line breaks are purely for human readability — highly recommended!

Real-life example (imagine we have a table called students):

Always write it the “good” way — your future self (and teammates) will thank you!

2. Comments in SQL

Comments are notes in your code that the database completely ignores. They are only for humans — to explain what the query does, why you wrote it a certain way, or to temporarily disable parts of code.

There are two ways to write comments in SQL:

A. Single-line comment → use — (two dashes) Everything after — on that line is ignored.

B. Multi-line comment → use /* … */ Everything between /* and */ is ignored, even across many lines.

Pro Tip: Use comments generously! Especially when:

• The query is complex
• You’re doing something tricky
• You’re about to share the query with your team

3. Case Sensitivity

Here’s the golden rule that confuses almost everyone at first:

SQL keywords are NOT case-sensitive.

You can write SELECT, select, SeLeCt, sElEcT — the database treats them all the same.

BUT — the actual data (values inside tables) IS case-sensitive in most databases!

Examples:

Important differences between popular databases (2026 status):

Best Practice (what most professionals do):

• Write keywords in UPPERCASE (SELECT, FROM, WHERE, etc.)
• Write table and column names exactly as they were created (usually lowercase or snake_case)
• Be careful with string comparisons — use functions like LOWER() or UPPER() if you want case-insensitive search:

4. Semicolon Usage (;)

The semicolon ; is like the full stop (period) at the end of an English sentence.

When do you need it?

Rule of Thumb for 2026: Always put a semicolon at the end of every SQL statement. It’s safe, portable, and prevents 90% of “why isn’t my query running?” errors.

Funny real-life story: A junior developer once spent 3 hours wondering why his query failed… only to realize he forgot the ; in a production script. The database silently waited for more input — classic!

Quick Recap with a Full Example

See? Clean, commented, properly cased, and ends with ;.

That’s it for SQL Syntax Basics! You now know how to write clean, readable, and correct SQL.