The mysql command line utility can be used to build databases, manipulate them, etc. It can also be used as an ad-hoc query tool with HTML-snippet output. Consider this code:
mysql -e "SELECT * FROM mytable WHERE somecondition='somevalue'"
The resulting output will be a mess of +, - and | characters used to frame boxes around the values. Now consider instead:
mysql -H -e "SELECT * FROM mytable WHERE somecondition='somevalue'"
The output of this is
code that can be cut-and-pasted into your HTML editor of choice. Complex queries not easily put into a single -e string can be done thus:
mysql -H < myqueries.sql
Note that no HTML is generated for any query that does not have a result set (like INSERT or UPDATE).
Change the -H to a -X to get XML output (without a DTD/XSL description, unfortunately).