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| | | valign='top' | '''Errors''' | | | valign='top' | '''Errors''' |
| − | |'''[[#Errors|BXDB0003]] is raised if the databse is not ''persistent'' (stored on disk).<br/>'''[[XQuery Errors#Functions Errors|FODC0002]]''' is raised if the addressed resource cannot be retrieved.<br/>'''[[XQuery Errors#Functions Errors|FODC0007]]''' is raised if the specified path is invalid. | + | |'''[[#Errors|BXDB0003]]''' is raised if the databse is not ''persistent'' (stored on disk).<br/>'''[[XQuery Errors#Functions Errors|FODC0002]]''' is raised if the addressed resource cannot be retrieved.<br/>'''[[XQuery Errors#Functions Errors|FODC0007]]''' is raised if the specified path is invalid. |
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| | | valign='top' | '''Examples''' | | | valign='top' | '''Examples''' |
Revision as of 23:54, 25 May 2012
This XQuery Module contains functions for processing databases from within XQuery. Existing databases can be opened and listed, its contents can be directly accessed, documents can be added to and removed, etc. All functions are introduced with the db: prefix, which is linked to the statically declared http://basex.org/modules/db namespace.
Conventions
All functions in this module are assigned to the http://basex.org/modules/db namespace, which is statically bound to the db prefix.
All errors are assigned to the http://basex.org/errors namespace, which is statically bound to the bxerr prefix.
Database Nodes
Many function signatures in this and other modules share $db as argument to reference an existing database. The argument may either be a string, denoting the name of the addressed database, or a single node from an already opened database. The following errors may be raised by these functions:
- BXDB0001 is raised if
$db references an XML node that is not stored in a database, or is no database fragment.
- BXDB0002 is raised if the addressed database cannot be opened.
Last not but least, the argument may also reference a BaseX-specific database fragment. All XML fragments can be converted to database fragments by applying the transform expression on an XML fragment:
copy $c := element hello { 'world' }
modify ()
return db:text($c, 'world')
General Functions
db:info
| Signatures
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db:info($db as item()) as element(Database)
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| Summary
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Returns meta information on the database specified by $db.
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db:list
| Signatures
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db:list() as xs:string*
db:list($db as item()) as xs:string*
db:list($db as item(), $path as xs:string) as xs:string*
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| Summary
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Returns an xs:string sequence with the names of all databases.
If $db is specified, all documents and raw files of the specified database are returned.
The list of resources can be further restricted by the $path argument.
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| Examples
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db:list("docs") returns the names of all documents from the database named docs.
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db:list-details
| Signatures
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db:list-details() as element(database)*
db:list-details($db as item()) as element(resource)*
db:list-details($db as item(), $path as xs:string) as element(resource)*
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| Summary
|
Returns an element sequence with the names of all databases together with their database path, the number of stored resources and the date of modification.
If $db is specified, all documents and raw files of the specified database together with their content-type, the modification date and the resource type are returned.
The list of resources can be further restricted by the $path argument.
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| Examples
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db:list-details("docs") returns the names plus additional data of all documents from the database named docs.
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db:open
| Signatures
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db:open($db as item()) as document-node()*
db:open($db as item(), $path as xs:string) as document-node()*
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| Summary
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Returns a sequence with all document nodes contained in the database specified by $db.
The document nodes to be returned can be restricted by the $path argument.
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| Examples
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db:open("docs") returns all documents from the database named docs.db:open("docs", "one") returns all documents from the database named docs in the subpath one.
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db:open-id
| Signatures
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db:open-id($db as item(), $id as xs:integer) as node()
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| Summary
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Opens the database specified by $db and returns the node with the specified $id value.
Each database node has a persistent id, which remains valid after update operations. If no updates are performed, the pre value can be requested, which provides access to database nodes in constant time.
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db:open-pre
| Signatures
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db:open-pre($db as item(), $pre as xs:integer) as node()
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| Summary
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Opens the database specified by $db and returns the node with the specified $pre value.
The pre value provides access to a database node in constant time, but it is transient, i.e., it may change when database updates are performed.
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| Errors
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BASX0004 is raised if the specified $pre value does not exist in the database.
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| Examples
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db:open-pre("docs", 0) returns the first database node from the database named docs.
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db:system
| Signatures
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db:system() as element(system)
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| Summary
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Returns information on the database system, such as the database path and current database settings.
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Read Operations
db:attribute
| Signatures
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db:attribute($db as item(), $string as item()) as attribute()*
db:attribute($db as item(), $string as item(), $attname as xs:string) as attribute()*
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| Summary
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Returns all attribute nodes of the database specified by $db that have $string as string value. If available, the value index is used to speed up evaluation.
If $attname is specified, the resulting attribute nodes are filtered by their attribute name.
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| Examples
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db:attribute("DB", "QUERY", "id")/.. returns the parents of all id attribute nodes of the database DB that have QUERY as string value.
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db:attribute-range
Template:Mark
| Signatures
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db:attribute-range($db as item(), $min as xs:string, $max as xs:string) as text()*
db:attribute-range($db as item(), $min as xs:string, $max as xs:string, $attname as xs:string) as attribute()*
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| Summary
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Returns all attributes of the database specified by $db, the string values of which are larger than or equal to $min and smaller than or equal to $max. If available, the value index is used to speed up evaluation.
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| Examples
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db:attribute-range("DB", "id456", "id473", 'id') returns all @id attributes of the database DB that have a string value in between id456 and id473.
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db:fulltext
| Signatures
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db:fulltext($db as item(), $terms as xs:string) as text()*
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| Summary
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Returns all text nodes from the full-text index of the database specified by $db that contain the text specified as $terms.
The options used for building the full-text will also be applied to the search terms. As an example, if the index terms have been stemmed, the search string will be stemmed as well.
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| Errors
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BXDB0004 is raised if the full-text index is not available.
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| Examples
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db:fulltext("DB", "QUERY") returns all text nodes of the database DB that contain the string QUERY.
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db:node-id
| Signatures
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db:node-id($nodes as node()*) as xs:integer*
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| Summary
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Returns the id values of all $nodes of the database specified by $db.
Each database node has a persistent id, which remains valid after update operations. If no updates are performed, the pre value can be requested, which provides access to database nodes in constant time.
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db:node-pre
| Signatures
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db:node-pre($nodes as node()*) as xs:integer*
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| Summary
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Returns the pre values of all $nodes of the database specified by $db.
The pre value provides access to a database node in constant time, but it is transient, i.e., it may change when database updates are performed.
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| Examples
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db:node-pre(doc("input")) returns 0 if the database input contains a single document.
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db:retrieve
| Signatures
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db:retrieve($db as item(), $path as xs:string) as xs:base64Binary
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| Summary
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Returns a binary database resource addressed by $db and $path.
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| Errors
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BXDB0003 is raised if the databse is not persistent (stored on disk).
FODC0002 is raised if the addressed resource cannot be retrieved.
FODC0007 is raised if the specified path is invalid.
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| Examples
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declare option output:method 'raw';
db:retrieve("DB", "music/01.mp3") returns the specified audio file as raw data.
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db:text
| Signatures
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db:text($db as item(), $string as item()) as text()*
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| Summary
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Returns all text nodes of the database specified by $db that have $string as their string value. If available, the value index is used to speed up evaluation.
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| Examples
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db:text("DB", "QUERY")/.. returns the parents of all text nodes of the database DB that match the string QUERY.
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db:text-range
Template:Mark
| Signatures
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db:text-range($db as item(), $min as xs:string, $max as xs:string) as text()*
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| Summary
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Returns all text nodes of the database specified by $db that are located in between the $min and $max strings. If available, the value index is used to speed up evaluation.
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| Examples
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db:text-range("DB", "2000", "2001") returns all text nodes of the database DB that are found in between 2000 and 2001.
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Updates
All functions in this section are treated as updating: they are not immediately executed, but queued on a pending update list, which is processed after the actual query has been evaluated. The XQuery Update page gives more insight into the relevant concepts.
db:add
| Signatures
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db:add($db as item(), $input as item()) as empty-sequence()
db:add($db as item(), $input as item(), $path as xs:string) as empty-sequence()
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| Summary
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Adds documents specified by $input to the database $db and the specified $path.
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| Errors
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FODC0002 is raised if $input is a string representing a path, which cannot be read.
FOUP0001 is raised if $input is not a string and not a document node.
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| Examples
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db:add("DB", "/home/dir/doc.xml") adds the file /home/dir/doc.xml to the database DB.db:add("DB", "<a/>", "doc.xml") adds a document with content <a/> to the database DB under the name doc.xml.db:add("DB", document { <a/> }, "doc.xml") adds the document node to the database DB under the name doc.xml.db:add("DB", "/home/dir", "docs/dir") adds all documents in /home/dir to the database DB under the path docs/dir.
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db:delete
| Signatures
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db:delete($db as item(), $path as xs:string) as empty-sequence()
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| Summary
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Deletes document(s), specified by $path, from the database $db.
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| Examples
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db:delete("DB", "docs/dir/doc.xml") deletes the document docs/dir/doc.xml in the database DB.db:delete("DB", "docs/dir") deletes all documents with paths beginning with docs/dir in the database DB.
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db:optimize
| Signatures
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db:optimize($db as item()) as empty-sequence()
db:optimize($db as item(), $all as xs:boolean) as empty-sequence()
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| Summary
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Optimizes the meta data and indexes of the database $db.
If $all is set to true(), the complete database will be rebuilt.
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| Errors
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BASX0014 is raised if an error occurs during optimizing the data structures.
BASX0015 is raised if the $all flag is set to true(), but the database is an in-memory database.
BASX0016 is raised if the database $db is in use by other user(s).
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| Examples
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db:optimize("DB") optimizes the database structures of the database DB.db:optimize("DB", true()) optimizes all database structures of the database DB.
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db:rename
| Signatures
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db:rename($db as item(), $path as xs:string, $newpath as xs:string) as empty-sequence()
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| Summary
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Renames document(s), specified by $path to $newpath in the database $db.
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| Errors
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BASX0013 is raised if new document name(s) will be empty.
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| Examples
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db:rename("DB", "docs/dir/doc.xml", "docs/dir/newdoc.xml") renames the document docs/dir/doc.xml to docs/dir/newdoc.xml in the database DB.db:rename("DB", "docs/dir", "docs/newdir") renames all documents with paths beginning with docs/dir to paths beginning with docs/newdir in the database DB.
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db:replace
| Signatures
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db:replace($db as item(), $path as xs:string, $input as item()) as empty-sequence()
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| Summary
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Replaces a document, specified by $path, in the database $db with the content of $input.
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| Errors
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BASX0012 is raised if $path is not a single document path.
FODC0002 is raised if $input is a string representing a path, which cannot be read.
FOUP0001 is raised if $input is not a string and not a document node.
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| Examples
|
db:replace("DB", "docs/dir/doc.xml", "/home/dir/doc.xml") replaces the content of the document docs/dir/doc.xml in the database DB with the content of the file /home/dir/doc.xml.db:replace("DB", "docs/dir/doc.xml", "<a/>") replaces the content of the document docs/dir/doc.xml in the database DB with <a/>.db:replace("DB", "docs/dir/doc.xml", document { <a/> }) replaces the content of the document docs/dir/doc.xml in the database DB with the specified document node.
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db:store
| Signatures
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db:store($db as item(), $path as xs:string, $data as item()) as empty-sequence()
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| Summary
|
Stores a binary resource specified by $data in the database specified by $db and the location specified by $path.
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| Errors
|
BXDB0003 is raised if the databse is not persistent (stored on disk).
FODC0007 is raised if the specified path is invalid.
FOUP0002 is raised if the resource cannot be stored at the specified location.
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| Examples
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db:store("DB", "video/sample.mov", file:read-binary('video.mov')) stores the addressed video file at the specified location.
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db:output
Template:Mark
| Signatures
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db:output($data as item()*) as empty-sequence()
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| Summary
|
This function can be used to both perform updates and return results in a single query. The argument of the function will be evaluated, and the resulting value will be cached and returned after the updates on the pending update list have been processed.
The function can only be used together with updating expressions; if the function is called within a transform expression, its results will be discarded.
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| Examples
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db:output("Prices have been deleted."), delete node //price deletes all price elements in a database and returns an info message.
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Helper Functions
db:exists
| Signatures
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db:exists($db as item()) as xs:boolean
db:exists($db as item(), $path as xs:string) as xs:boolean
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| Summary
|
Checks if the database specified by $db or the resource specified by {[Mono|$path}} exists. false is returned if a database directory has been addressed.
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| Examples
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db:exists("DB") returns true if the database DB exists.db:exists("DB", "resource") returns true if resource is an XML document or a raw file.
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db:is-raw
| Signatures
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db:is-raw($db as item(), $path as xs:string) as xs:boolean
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| Summary
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Checks if the specified resource in the database $db and the path $path exists, and if it is a raw file.
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| Examples
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db:is-raw("DB", "music/01.mp3") returns true.
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db:is-xml
| Signatures
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db:is-xml($db as item(), $path as xs:string) as xs:boolean
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| Summary
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Checks if the specified resource in the database $db and the path $path exists, and if it is an XML document.
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| Examples
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db:is-xml("DB", "dir/doc.xml") returns true.
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db:content-type
| Signatures
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db:content-type($db as item(), $path as xs:string) as xs:string
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| Summary
|
Retrieves the content type of a resource in the database $db and the path $path.
The file extension is used to recognize the content-type of a resource stored in the database. Content-type application/xml will be returned for any XML document stored in the database, regardless of its file name extension.
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| Errors
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FODC0002 is raised if the addressed resource is not found or cannot be retrieved.
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| Examples
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db:content-type("DB", "docs/doc01.pdf") returns application/pdf.db:content-type("DB", "docs/doc01.xml") returns application/xml.db:content-type("DB", "docs/doc01") returns application/xml, if db:is-xml("DB", "docs/doc01") returns true.
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db:event
| Signatures
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db:event($name as xs:string, $query as item()) as empty-sequence()
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| Summary
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Executes a $query and sends the resulting value to all clients watching the Event with the specified $name. The query may also perform updates; no event will be sent to the client that fired the event.
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| Errors
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BASX0009 is raised if the specified event is unknown.
SEPM0016 is raised if serialization errors occurred while sending the value.
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Changelog
Version 7.2.1
Version 7.1
Version 7.0
