How to give comments in SQL

I am working in SQL. What is the complete explanation for using comments in SQL, with some example code?

Answer

MySQL Server supports three comment styles:

From a # character to the end of the line.

From a -- sequence to the end of the line. In MySQL, the “– ” (double-dash) comment style requires the second dash to be followed by at least one whitespace or control character (such as a space, tab, newline, and so on). This syntax differs slightly from standard SQL comment syntax, as discussed in Section 1.8.2.5, “’–‘ as the Start of a Comment”.

From a /* sequence to the following */ sequence, as in the C programming language. This syntax enables a comment to extend over multiple lines because the beginning and closing sequences need not be on the same line.

Reference http://dev.mysql.com/doc/refman/5.0/en/comments.html