Comments in BigQuery

Comments in BigQuery are used to include explanatory notes or documentation within SQL code, making it easier to understand. Comments are ignored by the BigQuery interpreter and do not affect the execution of SQL statements.

There are two main types of comments in SQL:

• Single-line comments
• Multi-line comments

1. Single-Line Comments

Single-line comments start with two hyphens (--). Everything after the -- on that line is treated as a comment.

SQL Syntax

-- This is a single-line comment
SELECT * FROM employees; -- This comment follows an SQL statement    

2. Multi-Line Comments

Multi-line comments start with /* and end with */. They can span multiple lines.

SQL Syntax

/* This is a multi-line comment
   which spans multiple lines */
SELECT * FROM employees;

/* This is another multi-line comment */
SELECT name, department FROM employees;    

Best Practices

• Use comments to explain complex SQL queries or business logic.
• Keep comments clear and concise.
• Regularly update comments to ensure they remain accurate as the code changes.

By using comments effectively, we can make SQL code more maintainable and understandable for ourselves and others who work with the code in the future.