The majority of the topics we're investigating in this chapter can be demonstrated through sorting the rows of a table. This common task is a very useful way to assist users in quickly finding the information they need. There are, naturally, a number of ways in which the task can be accomplished.
A common solution for data sorting is to perform it on the server. Data in tables often comes from a database, which means that the code that pulls it out of the database can request it in a given sort order (using, for example, the SQL language's ORDER BY clause). If we have server-side code at our disposal, it is straightforward to begin with a reasonable default sort order.
Sorting is most useful, though, when the user can determine the sort order. A common user interface for this is to make the table headers (<th>) of sortable columns into links. These links can go to the current page, but with a query string appended indicating the column to...