SQL Comments

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

Comments are not supported in Microsoft Access databases.

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:

--Select all:
SELECT * FROM Customers

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

SELECT * FROM Customers -- WHERE City='Berlin'

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

--SELECT * FROM Customers;
SELECT * FROM Products;

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:

/*Select all the columns
of all the records
in the Customers table:*/
SELECT * FROM Customers

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

/* SELECT * FROM Customers
SELECT * FROM Products
SELECT * FROM Orders
SELECT * FROM Categories */
SELECT * FROM Suppliers

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

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

SELECT CustomerName, /*City,*/ Country FROM Customers

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

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