Comment in MySQL

How to Add Comment in MySQL?

Using comments in MySQL is a great approach to describing and explaining your code. This benefits you and other developers working on the same project. With your MySQL code, you can include comments to clarify the rationale or logic behind a specific statement or query. The MySQL server ignores comments while query execution and they are only for the developer's reference. Adding comments can improve the readability of your code and help other developers better comprehend it.

Including comments in MySQL code is critical, especially when working on large-scale projects with several engineers. It can also help you revisit and comprehend your code in the future.

Finally, adding a comment in MySQL code is a simple and effective technique to increase its readability and maintainability. It is strongly advised to use comments to explain the logic behind your code and make it easier to understand for others.

Syntax

Here's how to add comments in MySQL:

1. Single-line comment: To add a single-line comment, begin the line with two hyphens (--) followed by your comment. The comment will remain till the line is finished. Example:

2. Multi-line comment: To add a multi-line comment, begin with /* and end with */. Everything in between these two symbols is a comment. Example:

3. Commenting out code: You can also comment out code temporarily for testing or debugging purposes. To do this, surround the code with /* and */. Example:

Syntax Using # Symbol

Adding a comment in MySQL is valuable when working with sophisticated queries or huge databases. The # symbol is one way to add a comment. The syntax for inserting a comment with the # sign is straightforward. Add the # symbol at the end of the line of code, followed by your comment.

For instance, if you want to add a comment to a query that selects all columns from a table called employees, the code would be as follows:

The comment, in this case, is This is a comment, and it has no effect on the query's execution. However, when collaborating with other developers or revisiting old code, using comments is beneficial since it offers context and clarity to the goal of the code.

Syntax Using -- Symbol

The -- sign is used in MySQL to add single-line comments to the code. The comment begins with -- and continues until the end of the line. Here's an example of how to use this syntax in MySQL to add a comment:

The comment in this example begins with -- and concludes at the end of the line.

Syntax Using /* and */ symbols

MySQL allows you to add comments to your code in a variety of methods, including utilizing the /* and */ symbols. Here's an example of how to add comments to your MySQL code using this:

The comments in this example are surrounded by the /* and */ symbols. Anything between these symbols is considered a comment by MySQL and will not be processed. This syntax enables you to add comments to many lines of code simultaneously.

It's important to note that comments using this syntax can also comment out lines of code. For example:

The first SELECT statement in this example has been commented out using the /* and */ characters. This allows you to temporarily disable code without having to delete it completely.

Example - Comment on a Single Line

In MySQL, use the double-dash -- symbol to add a comment to a single line. Any content put after this symbol on the same line is considered a comment and will be disregarded by MySQL.

For example, to add a comment to a query, you can write:

The comment in this example begins after the double-dash -- symbol and concludes at the end of the line. MySQL does not execute the text This is a comment; it is intended to provide information or context for the person viewing the code.

Example - Comment on Multiple Lines

We can also comment on multiple lines of code in MySQL using the /* and */ symbols. Here is an example:

The comment in the above example begins with /* and finishes with */. Everything between those symbols is considered a comment by MySQL and will not be processed.

It is critical to remember that the comment symbols must always appear at the start and end of the comment block. MySQL will ignore any characters within the comment block, including semicolons and other special characters.