Menu
×
   ❮     
HTML CSS JAVASCRIPT SQL PYTHON JAVA PHP HOW TO W3.CSS C C++ C# BOOTSTRAP REACT MYSQL JQUERY EXCEL XML DJANGO NUMPY PANDAS NODEJS R TYPESCRIPT ANGULAR GIT POSTGRESQL MONGODB ASP AI GO KOTLIN SASS VUE DSA GEN AI SCIPY AWS CYBERSECURITY DATA SCIENCE
     ❯   

MySQL Tutorial

MySQL HOME MySQL Intro MySQL RDBMS

MySQL SQL

MySQL SQL MySQL SELECT MySQL WHERE MySQL AND, OR, NOT MySQL ORDER BY MySQL INSERT INTO MySQL NULL Values MySQL UPDATE MySQL DELETE MySQL LIMIT MySQL MIN and MAX MySQL COUNT, AVG, SUM MySQL LIKE MySQL Wildcards MySQL IN MySQL BETWEEN MySQL Aliases MySQL Joins MySQL INNER JOIN MySQL LEFT JOIN MySQL RIGHT JOIN MySQL CROSS JOIN MySQL Self Join MySQL UNION MySQL GROUP BY MySQL HAVING MySQL EXISTS MySQL ANY, ALL MySQL INSERT SELECT MySQL CASE MySQL Null Functions MySQL Comments MySQL Operators

MySQL Database

MySQL Create DB MySQL Drop DB MySQL Create Table MySQL Drop Table MySQL Alter Table MySQL Constraints MySQL Not Null MySQL Unique MySQL Primary Key MySQL Foreign Key MySQL Check MySQL Default MySQL Create Index MySQL Auto Increment MySQL Dates MySQL Views

MySQL References

MySQL Data Types MySQL Functions

MySQL Examples

MySQL Examples MySQL Editor MySQL Quiz MySQL Exercises MySQL Syllabus MySQL Study Plan MySQL Certificate


MySQL Comments


MySQL Comments

Comments are used to explain sections of SQL statements, or to prevent execution of SQL statements.


Single Line Comments

Single line comments start with --.

Any text between -- and the end of the line will be ignored (will not be executed).

The following example uses a single-line comment as an explanation:

Example

-- Select all:
SELECT * FROM Customers;
Try it Yourself »

The following example uses a single-line comment to ignore the end of a line:

Example

SELECT * FROM Customers -- WHERE City='Berlin';
Try it Yourself »

The following example uses a single-line comment to ignore a statement:

Example

-- SELECT * FROM Customers;
SELECT * FROM Products;
Try it Yourself »


Multi-line Comments

Multi-line comments start with /* and end with */.

Any text between /* and */ will be ignored.

The following example uses a multi-line comment as an explanation:

Example

/*Select all the columns
of all the records
in the Customers table:*/
SELECT * FROM Customers;
Try it Yourself »

The following example uses a multi-line comment to ignore many statements:

Example

/*SELECT * FROM Customers;
SELECT * FROM Products;
SELECT * FROM Orders;
SELECT * FROM Categories;*/
SELECT * FROM Suppliers;
Try it Yourself »

To ignore just a part of a statement, also use the /* */ comment.

The following example uses a comment to ignore part of a line:

Example

SELECT CustomerName, /*City,*/ Country FROM Customers;
Try it Yourself »

The following example uses a comment to ignore part of a statement:

Example

SELECT * FROM Customers WHERE (CustomerName LIKE 'L%'
OR CustomerName LIKE 'R%' /*OR CustomerName LIKE 'S%'
OR CustomerName LIKE 'T%'*/ OR CustomerName LIKE 'W%')
AND Country='USA'
ORDER BY CustomerName;
Try it Yourself »

×

Contact Sales

If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail:
sales@w3schools.com

Report Error

If you want to report an error, or if you want to make a suggestion, send us an e-mail:
help@w3schools.com

W3Schools is optimized for learning and training. Examples might be simplified to improve reading and learning. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use, cookie and privacy policy.

Copyright 1999-2024 by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3.CSS.