SQL Syntax

To effectively write SQL queries and commands, understanding the basic syntax rules is essential. SQL syntax defines how you structure commands so the database can interpret them correctly.

✍️ Basic Structure of SQL Statements

A SQL statement usually follows this general format:

COMMAND [columns]
FROM table_name
[WHERE condition]
[GROUP BY column]
[HAVING condition]
[ORDER BY column]
[LIMIT number];

• COMMAND: The action you want to perform (SELECT, INSERT, UPDATE, DELETE, etc.)
• Square brackets [ ] indicate optional parts of the statement.

⚠️ Key SQL Syntax Rules

1. SQL Keywords are not case sensitive
   • select, SELECT, and Select all work the same, but by convention, keywords are written in uppercase for clarity.
2. Statements end with a semicolon (;)
   • This marks the end of a command.
3. String values must be enclosed in single quotes sqlCopyEditWHERE name = 'John'
4. Identifiers (like table or column names) may require quotes if they contain spaces or special characters
   • Typically backticks ` in MySQL, double quotes " in PostgreSQL.
5. Whitespace (spaces, tabs, new lines) is ignored
   • Use whitespace to make code readable.

🧩 Example: Simple SELECT Query Syntax

SELECT first_name, last_name
FROM employees
WHERE department = 'Sales'
ORDER BY last_name ASC;

• Retrieves first and last names of employees in the Sales department, sorted by last name ascending.

🛠️ Common SQL Commands Syntax Overview

💡 Tips for Writing SQL Code

• Use uppercase for SQL keywords for readability.
• Always end statements with a semicolon.
• Write clear and meaningful identifiers for tables and columns.
• Format queries with indentation and line breaks to improve clarity.

🧠 Quick Recap