Finally the return clause tells the system what information we want to get back.

We're only interested if the actor appears in that video, and we're only interested if the actor's name ends in 'Lisa'.

The where clause then selects those pairs that we are actually interested in.

Taken together, the FLWOR expression is processing all possible pairs of videos and actors.

The for clause defines two range variables: one processes all the videos in turn, the other processes all the actors in turn.I've included this here because when I deploy the query I might want to set this variable differently for example, I might want to initialize it to doc('videos.xml'), or to the result of some complex query that locates the document in a database. The let clause simply declares a variable.Each video in the file is represented by a video element like this one: Let's suppose we want to find the titles of all the videos featuring an actor whose first name is Lisa. XPath is capable of doing some pretty powerful selections, and before we move on to XQuery proper, let's look at a more complex example. Again, this will all be familiar if you already know XPath. You can also use constructs like '/.' to go up one level, and to select an attribute. If the path starts with './' or './/' you can leave out the initial '.' (this assumes that the selection starts from the top of the tree, which is always the case in our examples).

The '/' in the path informally means 'go down one level', while the '//' means 'go down any number of levels'. The predicate is evaluated once for each selected element within the predicate, the expression '.' (dot) refers to the node that the predicate is testing, that is, the selected actor. actors/actor that indicates which elements we are interested in, and a predicate that indicates a test that the nodes must satisfy. This XPath expression has two parts: a path. We're calling it inside a predicate (the expression between the square brackets), which defines a condition that nodes must satisfy in order to be selected. This example used another function - ends-with() - that's new in XPath 2.0. Stylus Studio gives you the choice of a text view and a tree view: you use the buttons next to the Preview window to switch from one to the other. Technically, the result of this query is a sequence of two element nodes in a tree representation of the source XML document, and there are many ways a system might choose to display such a sequence on the screen. Different systems might display this output in different ways.

Flowr xquery what does for do