"A comment for a column can be specified with the COMMENT
option. The comment is displayed by the SHOW CREATE TABLE
and SHOW FULL COLUMNS
statements. This option is operational as of MySQL 4.1. (It is allowed but ignored in earlier versions.)"
As an example
--
-- Table structure for table 'accesslog'
--
CREATE TABLE accesslog (
aid int(10) NOT NULL auto_increment COMMENT 'unique ID for each access entry',
title varchar(255) default NULL COMMENT 'the title of the page being accessed',
path varchar(255) default NULL COMMENT 'the local path of teh page being accessed',
....
) TYPE=MyISAM;
You can use single line comments:
-- this is a comment
# this is also a comment
Or a multiline comment:
/*
multiline
comment
*/
/* comment here */
here is an example: SELECT 1 /* this is an in-line comment */ + 1;
From here you can use
# For single line comments
-- Also for single line, must be followed by space/control character
/*
C-style multiline comment
*/
Three types of commenting are supported
Hash base single line commenting using #
Select * from users ; # this will list users
Select * from users ; -- this will list users
Note : Its important to have single white space just after --
3) Multi line commenting using /* */
Select * from users ; /* this will list users */
Source: Stackoverflow.com