Comment In SQL

How do you add comments in SQL?

Comments in SQL are used to explain code, making it more readable and understandable for developers. They are ignored by the SQL engine during execution.

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Description

Example H2

Example H3

Comments are crucial for writing maintainable and understandable SQL code. They act as annotations, clarifying the purpose of specific code blocks or individual statements. This is especially important in larger projects where multiple developers might be working on the same database. Comments help everyone understand the logic behind the queries, making debugging and modifications easier. SQL supports two primary ways to add comments: single-line and multi-line comments. Single-line comments are useful for brief explanations, while multi-line comments are ideal for longer descriptions or complex logic explanations. Using comments consistently throughout your SQL code improves its overall readability and maintainability.

Why Comment In SQL is important

Comments enhance code readability and maintainability, making it easier for developers to understand, modify, and debug SQL code, especially in large projects.

Comment In SQL Example Usage


-- This is a single-line comment

SELECT
    employee_id,
    first_name,
    last_name
FROM
    employees;

/* This is a multi-line comment.
It can span multiple lines
to explain more complex
logic or sections of code. */

-- Example of a comment within a query
SELECT
    order_id,
    order_date
FROM
    orders
WHERE
    order_date > '2023-01-01' -- Filtering orders placed after January 1, 2023
;

Comment In SQL Syntax

Common Mistakes

Forgetting to add comments, leading to unclear code.
Using comments that are too brief or too general, not providing sufficient context.
Using incorrect comment syntax, leading to errors or the comment being ignored.

Frequently Asked Questions (FAQs)

Why are comments essential in SQL scripts that multiple developers touch?

Comments act as in-line documentation that explains why a query exists and what each block is doing. When several engineers collaborate on the same database, clear comments shorten the learning curve, speed up debugging, and reduce the risk of accidental regressions. In short, well-placed comments turn opaque SQL into maintainable, future-proof code.

When should I use single-line comments versus multi-line comments in SQL?

Use single-line comments (typically prefixed with --) for quick, one-sentence explanations or to disable a single statement during testing. Reserve multi-line comments (enclosed by /* ... */) for longer narratives—such as outlining complex join logic, documenting business rules, or providing a changelog. Choosing the right style keeps your scripts readable without cluttering the query window.

How can a modern SQL editor like Galaxy help me comment my queries more consistently?

Galaxy’s context-aware AI copilot can auto-generate descriptive comment stubs, propose column descriptions, and even update existing comments when you refactor a query. Combined with its fast desktop UI and collaborative Collections feature, Galaxy ensures every teammate sees and reuses well-commented, endorsed SQL instead of pasting undocumented snippets in Slack.