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Asked: 2024-09-27T00:21:38+05:30 In:

how do you comment in sql

Subject: How to Comment in SQL?

Hi there,

I hope you can help me out with something that’s been confusing me recently. I’m currently learning SQL, and I’ve come across a bunch of different resources and tutorials. However, I keep stumbling upon the need to add comments in my SQL queries, but I’m not quite sure how to do it correctly.

From what I’ve gathered, comments are essential for making my code more understandable, especially when I’m working on complex queries or collaborating with others. I want to add explanations for what different sections of my SQL code do or why certain approaches were taken. But I’m unclear about the different comment syntax I should use.

I’ve seen some queries with double dashes (–) and others that use /* and */ for block comments. Is there a specific scenario where I should use one over the other? Plus, are there any best practices for commenting that you could share? I want to ensure that my comments enhance the readability of my SQL code, instead of making it cluttered or confusing.

Thanks in advance for your help!

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    2 Answers

    1. So, like, commenting in SQL is kinda easy, I think? 🤔

      You can make comments in a couple of ways. First, if you wanna do a single-line comment, you can just put two dashes like this:

      -- This is a comment

      And then anything after those dashes on that line won’t be read by SQL, I guess? Like it just ignores it. Cool, right?

      But if you wanna do comments that go on for, like, multiple lines, you can use this thing:

      /* This is a 
multi-line comment */

      So, yeah! Just make sure you don’t mess up the syntax or anything. Or else, it might break your code, which would totally suck! 😅

      Hope that helps! 🙌

    2. In SQL, there are two primary ways to add comments into your code, enhancing readability and providing context for your future self or other developers who may work with your scripts. The first method is using single-line comments, which can be achieved by prefixing your comment with two hyphens (–) or a hash (#), depending on the SQL dialect you are using. For example, if you want to explain a complex JOIN operation, you can write:

      SELECT * FROM employees -- Fetch all employee records
JOIN departments ON employees.dept_id = departments.id;

      For multi-line comments, SQL offers a block comment syntax enclosed within /* and */. This is especially useful for longer explanations or when temporarily disabling chunks of code. For instance, if you’re documenting a lengthy stored procedure or providing a detailed explanation about why a specific condition is used, you might use the following:

      /*
This procedure retrieves all sales records
for the current fiscal year, including both
domestic and international sales to ensure
we have a comprehensive view of performance.
*/
SELECT * FROM sales WHERE sale_date >= '2023-01-01';

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