DB2 10.5 for Linux, UNIX, and Windows

Comments

Comments are allowed in the prolog or query body. Comments do not affect query processing.

A comment is composed of a string that is delimited by the symbols (:and :). The following example is a comment in XQuery:

(: A comment. You can use comments to make your code easier to understand. :)

The following general rules apply to using comments in DB2® XQuery:

Comments can be used wherever ignorable whitespace is allowed. Ignorable whitespace is whitespace that is not significant to the expression results.
Comments are not allowed in constructor content.
Comments can nest within each other, but each nested comment must have open and close delimiters, (: and :).

The following examples illustrate legal comments and comments that result in errors:

(: is this a comment? ::) is a legal comment.
(: is this a comment? ::) or an error? :) results in an error because there is an unbalanced nesting of the symbols (: and :).
(: commenting out a (: comment :) might be confusing, but is often helpful :) is a legal comment because a balanced nesting of comments is allowed.
"this is just a string :)" is a legal expression.
(: "this is just a string :)" :) results in an error. Likewise, "this is another string (:" is a legal expression, but (: "this is another string (:" :) results in an error. Literal content can result in an unbalanced nesting of comments.