Comments

Description

Comments can make your application easier to read and maintain. For example, you can include a comment within a statement to describe the purpose of that statement in your application. Comments in SQL statements (except for HINT) do not affect the execution of the statement. For information on using this specific form of comments with HINT, please refer to the HINT section.

In SQL statements, comments can appear between any keywords, parameters, or punctuation marks. You can include comments in statements in two ways:

• Multi-line comments: Start the comment with a slash and asterisk (/*), followed by the comment text. This text can span multiple lines. End the comment with an asterisk and a slash (*/). There is no need for spaces or line breaks between the start and end characters and the text.
• Single-line comments: Start the comment with two dashes (--), followed by the comment text. This text cannot extend to a new line. The comment ends with a newline character.

Examples

Multi-line Comment

SELECT /* This is a multi-line comment
          that can span multiple lines */
       column_name
FROM   table_name;

Single-line Comment

SELECT column_name -- This is a single-line comment
FROM   table_name;