Changes

=Features= ==FeaturesUpdating Expressions==

====insert====

====delete====

delete node //noden

The example query deletes all <code><noden></code> elements in your database. Note that, in contrast to other updating expressions, the delete expression allows multiple nodes as a target.

====replace====

====rename====

for $n in //nodeoriginalNode

All node <code>originalNode</code> elements are renamed. An iterative approach helps to modify multiple nodes within a single statement. Nodes on the descendant- or attribute-axis of the target are not affected. This has to be done explicitly as well.

===Non-Updating Expressions===

====transform=copy/modify/return===

copy $c := doc('example.xml')//nodeoriginalNode[@id = 1]

The node <code>originalNode</code> element with <code>@id=1</code> is copied and subsequently assigned a new QName using the rename expression. Note that the transform expression is the only expression which returns an actual XDM instance as a result. You can therefore use it to modify results and especially DOM nodes. This is an issue beginners are often confronted with. More on this topic can be found in the [[Update#Returning Results|XQUF Concepts]] section.

<texttitle>Copy of: Transform expression example</texttitle>

====update====

The {{MarkCode|Introduced with Version 7update}} expression is a BaseX-specific convenience operator for the {{Code|copy/modify/return}}construct: * Similar to the [[XQuery 3.0#Simple Map Operator|XQuery 3.0 map operator]], the value of the firstexpression is bound as context item, and the second expression performs updates on this item.8The updated item is returned as result:}}

* More than one node can be specified as source: <pre class="brush:xquery">db:open('data')//item update delete node text()</pre> * If wrapped with curly braces, update expressions can be chained: <pre class="brush:xquery"><root/> update { insert node <child/> into .} update { insert node "text" into child}</pre> ===transform with=== The {{Code|updatetransform with}} expression is a convenience operator for writing simple transform expressions.Similar was added to the current [[XQuery 3https://www.w3.0org/TR/xquery-update-30/#Simple Map Operator|id-transform-with XQuery Update 3.0 map operator]], the value of the firstexpression is bound as context item, and the second expression performs updates on this itemworking draft.The updated item It is returned as result. The first example a simple version of the [[#transformupdate|transformupdate]]expression and also available in BaseX: <pre class="brush:xquery"><xml>text</xml> transform with { replace value of node . with 'new-text'}</pre> ==Functions== ===Built-in Functions===expression{{Code|fn:put()}} is can be used to serialize XDM instances to secondary storage. It is executed at the end of a snapshot. Serialized documents therefore reflect all changes made effective during a query.

Please note that {{CodeAdditional [[Database Module#Updates|update}} is not part of the official XQuery Update Facility yet.It is currently being discussed in the [https://www.w3.org/Bugs/Public/show_bug.cgi?id=23643 W3 Bug Trackerdatabase functions]]exist for performing updates on document and database level.

===User-Defined Functions===

====fnIf an updating function item is called, the function call must be prefixed with the keyword {{Code|updating}}. This ensures that the query compiler can statically detect if an invoked function item will perform updates or not:put====

<pre class="brush:xquery">let $node := <node>TO-BE-DELETED</node>let $delete-text := %updating function($node) {{Code|fn:put delete node $node//text()}} is also part of the XQUF and enables the user to serialize XDM instances to secondary storage. It is executed at the end of a snapshot. Serialized documents therefore reflect all changes made effective during a queryreturn $node update ( updating $delete-text(.))</pre>

===Pending Update List===

<pre class="brush* '''Backups (1)''': {{Code|db:xml">create-backup()}}* '''XQuery Update''': {{Code|insert before}}, {{Code|delete}}, {{Code|replace}}, {{Code|rename}}, {{Code|replace value}}, {{Code|insertattribute}}, {{Code|insert into first}}, {{Code|insert into}}, {{Code|insert into last}}, {{Code|insert attribute}}, {{Code|insert into firstreplace valuerenameafter}}, {{Code|put}}replacedeleteinsert before* '''Documents''': {{Code|db:add()}}, {{Code|db:store()}}, {{Code|db:replace()}}, {{Code|db:rename()}}, {{Code|db:delete()}}, {{Code|db:optimize()}}, {{Code|db:flush()}},* '''Users''': {{Code|user:grant()}}, {{Code|user:password()}}, {{Code|user:drop()}}, {{Code|user:alter()}}, {{Code|user:create()}}* '''Databases''': {{Code|db:copy()}}, {{Code|db:drop()}}, {{Code|db:alter()}}, {{Code|db:create()}}</pre>* '''Backups (2)''': {{Code|db:restore()}}, {{Code|db:drop-backup()}}

It may be surprising to see <code>[[Database Module|db:create]]</code> on bottom in the lower part of this list. This means that newly created database cannot be accessed by the same query, which can be explained by the semantics of updating queries: all expressions can only be evaluated on databases that already exist while compiling and evaluating the queryis evaluated. As a resultconsequence, {{Code|db:create}} is mainly useful in the context of [[Commands#Basics|Command Scripts]], or [[Web Application]]s, in which a redirect to another page can be triggered after having created a database.

====Example====

===Returning Results===

It By default, it is not possible to mix different types of expressions in a query result. The outermost expression of a query must either be a collection of updating or non-updating expressions. The only way to perform any updating queries and return a result at the same time is to use the BaseX-specific <code>[[Database Module#db:output|dbBut there are two ways out:output()]]</code> function, which caches the results of its arguments at runtime and returns them after all updates have been processed.

Example* The BaseX-specific <code>[[Database Module#db: Perform output|db:output()]]</code> function bridges this gap: it caches the results of its arguments at runtime and returns them after all updates have been processed. The following example performs an update and return returns a success message.:

If you want to modify temporary nodes in main memory without storing them in a database, you can use * With the [[UpdateOptions#transformMIXUPDATES|MIXUPDATES]] option, all updating constraints will be turned off. Returned nodes will be copied before they are modified by updating expressions. An error is raised if items are returned within a transform expression]]. ===Function Declaration===

To If you want to modify nodes in main memory, you can use updating expressions within a function, the {{Code[[Update#transform|%updating}} annotation has to be added to the function declaration. A correct declaration of a function that contains updating expressions (or one that calls updating functions) looks like this:  <pre class="brush:xquery">declare %updating function { ..transform expression]]. }</pre>

===Original Files===

In BaseX, all updates are performed on database nodes or in main memory. By default, update operations never do not affect the original input file(the info string "Updates are not written back" appears in the query info to indicate this). The following solutions exist to write XML documents and binary resources to disk:

===Indexes===

==Error Messages==

* Added: [[#update|update]]convenience operator