SQL Syntax and Statements - Introduction to SQL Vocabulary

SQL Syntax

SQL syntax defines the structure and format of commands you write to interact with a database. Think of it as grammar rules for the SQL language — it tells you how to write statements so the database understands what you want.

Basic SQL Syntax Rules

For reference, consider the following SQL statements.

SELECT column1, column2
FROM table_name
WHERE condition;

SELECT * FROM students;

• Keywords like SELECT, FROM, WHERE, etc., are not case-sensitive, but writing them in uppercase improves readability.
• Statements end with a semicolon ; — this marks the end of a complete command. In the above code, we have two commands.
• Strings must be in single quotes: for example, 'Delhi'.
• Column names and table names are written in lowercase or snake_case by convention, but they can be any valid identifier.
• Spaces between keywords and elements (like table names, column names, etc.) are required for clarity and correctness. Don't write SELECT*FROM — instead use SELECT * FROM.

Spacing and Formatting

• Always use a space between keywords: SELECT and FROM must be separated.
• Use commas between column names: SELECT name, age, city
• You can write SQL on one line or across multiple lines — indentation is optional but helpful for readability.

  SELECT name, age
FROM students
WHERE age>12;

SELECT name, age FROM students WHERE age>12;

Symbols in SQL Syntax

Symbol	Meaning	Example
*	Select all columns	SELECT * FROM students;
,	Separate columns in a list	SELECT name, age
' '	Wrap string values	WHERE city = 'Delhi'
=	Equality condition	WHERE age = 15
;	End of SQL statement	SELECT * FROM students;

Identifiers: Table and Column Names

• Table and column names must begin with a letter (A–Z).
• They can include letters, numbers, and underscores _.
• Avoid using SQL keywords like SELECT or WHERE as table or column names.
• If a name contains spaces or special characters, wrap it in double quotes (e.g., "student name").

Good Practices

• Use consistent indentation and line breaks for better readability.
• Use uppercase for SQL keywords and lowercase for table/column names.
• End every statement with a semicolon ; to avoid syntax errors.