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| | '''Summary''' | | | '''Summary''' |
− | |Opens the database {{Code|$db}} and returns the node with the specified {{Code|$pre}} value.<br/>The ''pre'' value provides access to a database node in constant time. It is not stored in the database. Instead, it is implicitly given by the order in which the XML nodes are visited by a SAX parser. As a result, it will change whenever a node with a smaller ''pre'' values is added to or deleted from a database. | + | |Opens the database {{Code|$db}} and returns the node with the specified {{Code|$pre}} value.<br/>The [[Node Storage#Node Table|PRE value]] provides access to a database node in constant time, but it will change whenever a node with a smaller ''pre'' values is added to or deleted from a database. |
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| | '''Errors''' | | | '''Errors''' |
Revision as of 23:36, 20 May 2013
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.
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
Template:Mark, the functions no longer accept database nodes as reference. Instead, the name of a database must now be specified.
Database nodes are XML nodes which are either stored in a persistent database or part of a so-called database fragment. All XML fragments can be converted to database fragments by e. g. applying the transform expression on an XML fragment:
copy $c := element hello { 'world' } modify () return $c
General Functions
db:system
Signatures
|
db:system() as element(system)
|
Summary
|
Returns information on the database system, such as the database path and current database settings. The output is similar to the INFO command.
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db:info
Signatures
|
db:info($db as xs:string) as element(database)
|
Summary
|
Returns meta information on the database $db . The output is similar to the INFO DB command.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
|
db:list
Signatures
|
db:list() as xs:string*
db:list($db as xs:string) as xs:string*
db:list($db as xs:string, $path as xs:string) as xs:string*
|
Summary
|
Returns a string sequence with the names of all databases:
- If a database
$db is specified, all documents and raw files of the specified database are returned.
- The list of resources can be further restricted by the
$path argument.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
|
Examples
|
db:list("docs") returns the names of all documents from the database named docs .
|
db:list-details
Signatures
|
db:list-details() as element(database)*
db:list-details($db as xs:string) as element(resource)*
db:list-details($db as xs:string, $path as xs:string) as element(resource)*
|
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 a database
$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
$path argument.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
|
Examples
|
db:list-details("docs") returns the names plus additional data of all documents from the database named docs .
|
db:backups
Signatures
|
db:backups() as element(backup)*
db:backups($db as xs:string) as element(backup)*
|
Summary
|
Returns an element sequence containing all available database backups. If a database $db is specified, the sequence will be restricted to the backups matching this database.
|
Examples
|
db:backups("factbook") returns all backups that have been made from the factbook database.
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db:event
Signatures
|
db:event($name as xs:string, $query as item()) as empty-sequence()
|
Summary
|
Executes a $query and sends the resulting value to all clients watching the Event with the specified $name . The query may also perform updates; no event will be sent to the client that fired the event.
|
Errors
|
BXDB0010 : the specified event is unknown.
SEPM0016 : serialization errors occurred while sending the value.
|
Read Operations
db:open
Signatures
|
db:open($db as xs:string) as document-node()*
db:open($db as xs:string, $path as xs:string) as document-node()*
|
Summary
|
Returns a sequence with all document nodes contained in the database $db . The document nodes to be returned can be restricted by the $path argument.
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
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Examples
|
db:open("docs") returns all documents from the database named docs .
db:open("docs", "one") returns all documents from the database named docs in the subpath one .
|
db:open-id
Signatures
|
db:open-id($db as xs:string, $id as xs:integer) as node()
|
Summary
|
Opens the database $db and returns the node with the specified $id value. Each database node has a persistent id, which remains valid after update operations. Access to the node id can be sped up by turning on the UPDINDEX option.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
BXDB0009 : the specified id value does not exist in the database.
|
db:open-pre
Signatures
|
db:open-pre($db as xs:string, $pre as xs:integer) as node()
|
Summary
|
Opens the database $db and returns the node with the specified $pre value. The PRE value provides access to a database node in constant time, but it will change whenever a node with a smaller pre values is added to or deleted from a database.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
BXDB0009 : the specified pre value does not exist in the database.
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Examples
|
db:open-pre("docs", 0) returns the first database node from the database named docs .
|
db:node-id
Signatures
|
db:node-id($nodes as node()*) as xs:integer*
|
Summary
|
Returns the id values of the nodes supplied by $nodes , which must all be database nodes. Each database node has a persistent id, which remains valid after update operations. If no updates have been performed on a database, the pre value is equal to the id value and can be requested instead.
|
Errors
|
BXDB0001 : $nodes contains a node which is not stored in a database.
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db:node-pre
Signatures
|
db:node-pre($nodes as node()*) as xs:integer*
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Summary
|
Returns the pre values of the nodes supplied by $nodes , which must all be database nodes. 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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BXDB0001 : $nodes contains a node which is not stored in a database.
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Examples
|
db:node-pre(doc("input")) returns 0 if the database input contains a single document.
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db:retrieve
Signatures
|
db:retrieve($db as xs:string, $path as xs:string) as xs:base64Binary
|
Summary
|
Returns a binary resource addressed by the database $db and $path as streamable xs:base64Binary .
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
BXDB0003 : the database is not persistent (stored on disk).
FODC0002 : the addressed resource cannot be retrieved.
FODC0007 : the specified path is invalid.
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Examples
|
declare option output:method 'raw'; db:retrieve("DB", "music/01.mp3") returns the specified audio file as raw data.
stream:materialize(db:retrieve("DB", "music/01.mp3")) returns a materialized representation of the streamable result.
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db:export
Template:Mark:
Signatures
|
db:export($db as xs:string, $path as xs:string) as empty-sequence()
db:export($db as xs:string, $path as xs:string, $params as item()) as empty-sequence()
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Summary
|
Exports the specified database $db to the specified file $path . Existing files will be overwritten. The $params argument contains serialization parameters (see Serialization for more details), which can either be specified
- as children of an
<output:serialization-parameters/> element, as defined for the fn:serialize() function; e.g.:
<output:serialization-parameters>
<output:method value='xml'/>
<output:cdata-section-elements value="div"/>
...
</serialization-parameters>
- as map, which contains all key/value pairs:
map { "method" := "xml", "cdata-section-elements" := "div", ... }
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Errors
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BXDB0002 : The addressed database does not exist or could not be opened.
|
Contents
db:text
Signatures
|
db:text($db as xs:string, $string as item()) as text()*
|
Summary
|
Returns all text nodes of the database $db that have $string as their string value. If available, the value index is used to speed up evaluation.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
|
Examples
|
db:text("DB", "QUERY")/.. returns the parents of all text nodes of the database DB that match the string QUERY .
|
db:text-range
Signatures
|
db:text-range($db as xs:string, $min as xs:string, $max as xs:string) as text()*
|
Summary
|
Returns all text nodes of the database $db that are located in between the $min and $max strings. If available, the value index is used to speed up evaluation.
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
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Examples
|
db:text-range("DB", "2000", "2001") returns all text nodes of the database DB that are found in between 2000 and 2001 .
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db:attribute
Signatures
|
db:attribute($db as xs:string, $string as item()) as attribute()*
db:attribute($db as xs:string, $string as item(), $attname as xs:string) as attribute()*
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Summary
|
Returns all attribute nodes of the database $db that have $string as string value. If available, the value index is used to speed up evaluation. If $attname is specified, the resulting attribute nodes are filtered by their attribute name.
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
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Examples
|
db:attribute("DB", "QUERY", "id")/.. returns the parents of all id attribute nodes of the database DB that have QUERY as string value.
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db:attribute-range
Signatures
|
db:attribute-range($db as xs:string, $min as xs:string, $max as xs:string) as attribute()*
db:attribute-range($db as xs:string, $min as xs:string, $max as xs:string, $attname as xs:string) as attribute()*
|
Summary
|
Returns all attributes of the database $db , the string values of which are larger than or equal to $min and smaller than or equal to $max . If available, the value index is used to speed up evaluation.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
|
Examples
|
db:attribute-range("DB", "id456", "id473", 'id') returns all @id attributes of the database DB that have a string value in between id456 and id473 .
|
db:fulltext
Signatures
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db:fulltext($db as xs:string, $terms as xs:string) as text()*
|
Summary
|
Returns all text nodes from the full-text index of the database $db that contain the text specified as $terms . The options used for building the full-text will also be applied to the search terms. As an example, if the index terms have been stemmed, the search string will be stemmed as well.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
BXDB0004 : the full-text index is not available.
|
Examples
|
db:fulltext("DB", "QUERY") returns all text nodes of the database DB that contain the string QUERY .
|
Updates
Important note: All functions in this section are updating functions: they will not be immediately executed, but queued on the Pending Update List, which will be processed after the actual query has been evaluated. This means that the order in which the functions are specified in the query does usually not reflect the order in which the code will be evaluated.
db:create
Template:Mark allow more than one input and path.
Signatures
|
db:create($db as xs:string) as empty-sequence()
db:create($db as xs:string, $inputs as item()*) as empty-sequence()
db:create($db as xs:string, $inputs as item()*, $paths as xs:string*) as empty-sequence()
|
Summary
|
Creates a new database with name $db and adds initial documents specified via $inputs to the specified $paths .
$inputs may be strings or nodes different than attributes. If the $input source is not a file or a folder, the $paths argument is mandatory. Please note that db:create will be placed last on the Pending Update List. As a consequence, a newly created database cannot be addressed in the same query.
|
Errors
|
FODC0002 : $inputs points to an unknown resource.
FOUP0001 : $inputs is neither string nor a document node.
BXDB0007 : $db is opened by another process.
BXDB0011 : $db is not a valid database name.
BXDB0012 : two db:create statements with the same database name were specified.
BXDB0013 : the number of specified inputs and paths differs.
|
Examples
|
db:create("DB") creates the empty database DB .
db:create("DB", "/home/dir/doc.xml") creates the database DB and adds the document /home/dir/doc.xml as initial content.
db:create("DB", <a/>, "doc.xml") creates the database DB and adds the document with content <a/> under the name doc.xml .
db:create("DB", "/home/dir/", "docs/dir") creates the database DB and adds the documents in /home/dir to the database under the path docs/dir .
db:create("DB", file:list('.')) adds all files of the current working directory to a new database.
|
db:drop
Signatures
|
db:drop($db as xs:string) as empty-sequence()
|
Summary
|
Drops the database $db and all connected resources.
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
BXDB0007 : $db is opened by another process.
|
Examples
|
db:drop("DB") drops the database DB .
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db:add
Signatures
|
db:add($db as xs:string, $input as item()) as empty-sequence()
db:add($db as xs:string, $input as item(), $path as xs:string) as empty-sequence()
|
Summary
|
Adds documents specified by $input to the database $db and the specified $path .
$input may be a string or a node different than attribute. If the $input source is not a file or a folder, $path must be specified.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
FODC0002 : $input points to an unknown resource.
FOUP0001 : $input is neither string nor a document node.
|
Examples
|
db:add("DB", "/home/dir/doc.xml") adds the file /home/dir/doc.xml to the database DB .
db:add("DB", <a/>, "doc.xml") adds a document node to the database DB under the name doc.xml .
db:add("DB", "/home/dir", "docs/dir") adds all documents in /home/dir to the database DB under the path docs/dir .
|
db:delete
Signatures
|
db:delete($db as xs:string, $path as xs:string) as empty-sequence()
|
Summary
|
Deletes document(s), specified by $path , from the database $db .
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
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Examples
|
db:delete("DB", "docs/dir/doc.xml") deletes the document docs/dir/doc.xml in the database DB .
db:delete("DB", "docs/dir") deletes all documents with paths beginning with docs/dir in the database DB .
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db:optimize
Signatures
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db:optimize($db as xs:string) as empty-sequence()
db:optimize($db as xs:string, $all as xs:boolean) as empty-sequence()
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Summary
|
Optimizes the meta data and indexes of the database $db . If $all is set to true() , the complete database will be rebuilt.
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
FOUP0002 : an error occurred while optimizing the database.
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Examples
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db:optimize("DB") optimizes the database structures of the database DB .
db:optimize("DB", true()) optimizes all database structures of the database DB .
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db:rename
Signatures
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db:rename($db as xs:string, $path as xs:string, $newpath as xs:string) as empty-sequence()
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Summary
|
Renames document(s), specified by $path to $newpath in the database $db .
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
BXDB0008 : new document names would be empty.
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Examples
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db:rename("DB", "docs/dir/doc.xml", "docs/dir/newdoc.xml") renames the document docs/dir/doc.xml to docs/dir/newdoc.xml in the database DB .
db:rename("DB", "docs/dir", "docs/newdir") renames all documents with paths beginning with docs/dir to paths beginning with docs/newdir in the database DB .
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db:replace
Signatures
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db:replace($db as xs:string, $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 , or adds it as a new document.
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Errors
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BXDB0002 : The addressed database does not exist or could not be opened.
BXDB0014 : $path points to a directory.
FODC0002 : $input is a string representing a path, which cannot be read.
FOUP0001 : $input is neither a string nor a document node.
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Examples
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db:replace("DB", "docs/dir/doc.xml", "/home/dir/doc.xml") replaces the content of the document docs/dir/doc.xml in the database DB with the content of the file /home/dir/doc.xml .
db:replace("DB", "docs/dir/doc.xml", "<a/>") replaces the content of the document docs/dir/doc.xml in the database DB with <a/> .
db:replace("DB", "docs/dir/doc.xml", document { <a/> }) replaces the content of the document docs/dir/doc.xml in the database DB with the specified document node.
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db:store
Signatures
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db:store($db as xs:string, $path as xs:string, $input as item()) as empty-sequence()
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Summary
|
Stores a binary resource specified by $input in the database $db and the location specified by $path .
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Errors
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BXDB0002 : The addressed database does not exist or could not be opened.
BXDB0003 : the database is not persistent (stored on disk).
FODC0007 : the specified path is invalid.
FOUP0002 : the resource cannot be stored at the specified location.
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Examples
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db:store("DB", "video/sample.mov", file:read-binary('video.mov')) stores the addressed video file at the specified location.
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db:output
Signatures
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db:output($result as item()*) as empty-sequence()
|
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 items will be cached and returned after the updates on the pending update list have been processed. As nodes may be updated, they will be copied before being cached. 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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db:flush
Signatures
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db:flush($db as xs:string) as empty-sequence()
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Summary
|
Explicitly flushes the buffers of the database $db . This command is only useful if AUTOFLUSH has been set to false .
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Errors
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BXDB0002 : The addressed database does not exist or could not be opened.
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Helper Functions
db:name
Template:Mark:
Signatures
|
db:name($node as node()) as xs:string
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Summary
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Returns the name of the database in which the specified database node $node is stored.
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Errors
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BXDB0001 : $nodes contains a node which is not stored in a database.
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db:path
Template:Mark:
Signatures
|
db:path($node as node()) as xs:string
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Summary
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Returns the path of the database document in which the specified database node $node is stored.
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Errors
|
BXDB0001 : $nodes contains a node which is not stored in a database.
|
db:exists
Signatures
|
db:exists($db as xs:string) as xs:boolean
db:exists($db as xs:string, $path as xs:string) as xs:boolean
|
Summary
|
Checks if the database $db or the resource specified by $path exists. false is returned if a database directory has been addressed.
|
Examples
|
db:exists("DB") returns true if the database DB exists.
db:exists("DB", "resource") returns true if resource is an XML document or a raw file.
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db:is-raw
Signatures
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db:is-raw($db as xs:string, $path as xs:string) as xs:boolean
|
Summary
|
Checks if the specified resource in the database $db and the path $path exists, and if it is a raw file.
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Errors
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BXDB0002 : The addressed database does not exist or could not be opened.
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Examples
|
db:is-raw("DB", "music/01.mp3") returns true .
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db:is-xml
Signatures
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db:is-xml($db as xs:string, $path as xs:string) as xs:boolean
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Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
|
Summary
|
Checks if the specified resource in the database $db and the path $path exists, and if it is an XML document.
|
Examples
|
db:is-xml("DB", "dir/doc.xml") returns true .
|
db:content-type
Signatures
|
db:content-type($db as xs:string, $path as xs:string) as xs:string
|
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.
|
Errors
|
BXDB0002 : The addressed database does not exist or could not be opened.
FODC0002 : the addressed resource is not found or cannot be retrieved.
|
Examples
|
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 .
|
Errors
Code
|
Description
|
BXDB0001
|
The referenced XML node is no database node, i.e. it is neither stored in a database nor represented as database fragment.
|
BXDB0002
|
The addressed database does not exist or could not be opened.
|
BXDB0003
|
The addressed database is not persistent (stored on disk).
|
BXDB0004
|
The database lacks an index structure required by the called function.
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BXDB0005
|
A query is expected to exclusively return database nodes of a single database.
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BXDB0006
|
A database path addressed with doc() contains more than one document.
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BXDB0007
|
A database cannot be updated because it is opened by another process.
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BXDB0008
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Database paths cannot be renamed to empty strings.
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BXDB0009
|
The addressed database id or pre value is out of range.
|
BXDB0010
|
The specified event is unknown.
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BXDB0011
|
The name of the specified database is invalid.
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BXDB0012
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A database can only be created once.
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BXDB0013
|
The number of specified inputs and paths differs.
|
BXDB0014
|
Path points to a directory.
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Changelog
- Version 7.7
- Version 7.6
- Updated: db:create: allow more than one input and path.
- Version 7.5
- Version 7.3
- Version 7.2.1
- Version 7.1
- Version 7.0