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Home >Online Product Documentation >Table of Contents >Simple XQuery FLWOR Expressions Simple XQuery FLWOR ExpressionsThe simplest XQuery FLWOR expression might be something like this:
This returns all of the
We can add a bit of substance by adding XQuery This returns all of the titles of videos released in 1999. If you know SQL, that XQuery probably looks reassuringly similar to the equivalent SQL statement: And if you know XPath, you might be wondering why our XQuery cannot be written as this: Well, you can. This XPath expression is completely equivalent to the FLWOR expression above, and furthermore, it is a legal XQuery query. In fact, every legal XPath expression is also legal in XQuery. Thus the first query in this section can be written as: Which style you prefer seems to depend on where you are coming from: if you have been using XML for years, especially XML with a deep hierarchy as found in "narrative" documents, then you will probably be comfortable with path expressions. But if you are more used to thinking of your data as representing a table, then the FLWOR style might suit you better. As you will see, FLWOR expressions are a lot more powerful than path expressions when it comes to doing joins. But for simple queries, the capabilities overlap and you have a choice. Although it might be true that in SQL every query is a SELECT statement, it is not so that in XQuery every query has to be a FLWOR expression. |
XML PRODUCTIVITY THROUGH INNOVATION ™
