Database Module
Revision as of 16:28, 19 November 2011 by CG (talk | contribs) (moved Database Functions to Database Module)
This module contains XQuery functions for handling databases from within XQuery. Existing databases can be opened and listed, index structures can be directly accessed, documents can be added to and removed from collections, etc. All functions are introduced with the db:
prefix, which is linked to the http://www.basex.org/modules/db
namespace.
A preview page contains all functions offered by the latest stable snapshot.
General Functions
db:info
Signatures | db:info($db as item()) as xs:string db:info($db as item(), $type as xs:string) as xs:string
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Summary | Returns information for a database. If $type is specified, the function returns information on a database index. It must be one of the values TEXT , ATTRIBUTE , FULLTEXT , PATH , TAG , or ATTNAME .
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Errors | BASX0001 is raised if the specified index is not available. |
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db:list
Signatures | db:list() as xs:string* db:list($db as xs:string) as xs:string* db:list($db as xs:string, $path as xs:string) as xs:string*
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Summary | 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 $path argument.Template:Mark: database and resource path are now specified as two separate arguments. |
db:open
Signatures | db:open($db as xs:string) as document-node()* db:open($db as xs:string, $path as xs:string) as document-node()*
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Summary | Returns a sequence with all document nodes contained in the database specified by $db . The returned documents may be filtered by the $path argument.Template:Mark: database and resource path are now specified as two separate arguments. |
Errors | BASX0003 is raised if the database is not found. |
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db:open-id
Signatures | db:open-id($db as item(), $id as xs:integer) as node()
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Summary | Opens the database specified by $db and returns the node with the specified $id value.In contrast to the pre value, the id will remain valid after update operations. |
Errors | BASX0004 is raised if the specified $id does not exist in the database.
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db:open-pre
Signatures | db:open-pre($db as item(), $pre as xs:integer) as node()
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Summary | Opens the database specified by $db and returns the node with the specified $pre value.
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Errors | BASX0004 is raised if the specified $pre value does not exist in the database.
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Examples |
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db:system
Signatures | db:system() as xs:string
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Summary | Prints information about the database system, including the database path and current database settings. |
Read Operations
db:attribute
Signatures | db:attribute($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 | Returns all attribute nodes that have $string as their string value.If $attname is specified, the resulting attribute nodes are filtered by their attribute name.
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Examples |
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db:fulltext
Signatures | db:fulltext($db as item(), $text as item()) as text()*
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Summary | Returns all text nodes from the full-text index that contain the string $text . The index full-text options are used for searching, i.e., if the index terms have been stemmed, the search string will be stemmed as well.
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Errors | BASX0001 is raised if the index is not available. |
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db:node-id
Signatures | db:node-id($nodes as node()*) as xs:integer*
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Summary | Returns the id values of all database nodes specified by $nodes . id values are pointers to database nodes, which are not changed by updates.
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db:node-pre
Signatures | db:node-pre($nodes as node()*) as xs:integer*
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Summary | Returns the pre values of all database nodes specified by $nodes . pre values are direct, internal pointers to database nodes, which might be changed by updates.
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Examples |
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db:retrieve
Signatures | db:retrieve($db as xs:string, $path as xs:string) as xs:raw
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Summary | Retrieves the binary resource specified by $path in the (implementation specific) xs:raw format.
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Errors | FODC0002 is raised if the addressed resource is not found or cannot be retrieved. |
Examples |
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db:text
Signatures | db:text($db as item(), $string as item()) as text()*
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Summary | Returns all text nodes that have $string as their string value.
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Examples |
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Updates
db:add
Signatures | db:add($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 | Add documents specified by $input to the database $db and the specified $path .
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Errors | BASX0002 is raised if $db is not a database node.BASX0003 is raised if $db is a string and a database with that name cannot be opened.FODC0002 is raised if $input is a string representing a path, which cannot be read.FOUP0001 is raised if $input is not a string and not a document node.
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Examples |
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db:delete
Signatures | db:delete($db as item(), $path as xs:string) as empty-sequence()
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Summary | Delete document(s), specified by $path in the database $db .
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Errors | BASX0002 is raised if $db is not a database node.BASX0003 is raised if $db is a string and a database with that name cannot be opened.
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Examples |
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db:optimize
Signatures | db:optimize($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 | Optimize the data structures of the database $db . If $all is set to true() , then the whole database will be rebuilt.
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Errors | BASX0002 is raised if $db is not a database node.BASX0003 is raised if $db is a string and a database with that name cannot be opened.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 $db is in use by other user(s).
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Examples |
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db:rename
Signatures | db:rename($db as item(), $path as xs:string, $newpath as xs:string) as empty-sequence()
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Summary | Rename document(s), specified by $path to $newpath in the database $db .
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Errors | BASX0002 is raised if $db is not a database node.BASX0003 is raised if $db is a string and a database with that name cannot be opened.BASX0013 is raised if new document name(s) will be empty. |
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db:replace
Signatures | db:replace($db as item(), $path as xs:string, $input as item()) as empty-sequence()
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Summary | Replace a document, specified by $path in the database $db with the content of $input .
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Errors | BASX0002 is raised if $db is not a database node.BASX0003 is raised if $db is a string and a database with that name cannot be opened.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 $input is not a string and not a document node.
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Examples |
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db:store
Signatures | db:store($db as xs:string, $path as xs:string, $data as item()) as empty-sequence()
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Summary | Stores a binary resource specified by $data at the location specified by $path .
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Errors | FOUP0002 is raised if the resource cannot be stored at the specified location. |
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Helper Functions
db:content-type
Signatures | db:content-type($db as xs:string, $path as xs:string) as xs:string
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Summary | Retrieves the content type of the resource specified by $path . Currently, the implementation uses the file extension to recognize the content-type of a resource stored in the database (this mechanism is provided by Java). Content-type application/xml will be returned for any XML document stored in the database, regardless of its file name extension.
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Errors | FODC0002 is raised if the addressed resource is not found or cannot be retrieved. |
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db:event
Signatures | db:event($name as xs:string, $query as item()) as empty-sequence()
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Summary | Executes a $query and sends the resulting value to all clients watching the Event with the specified $name . No event will be sent to the client that fired the event.
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Errors | BASX0009 is raised if the specified event is unknown. SEPM0016 is raised if serialization errors occurred while sending the value. |
db:exists
Signatures | db:exists($db as xs:string) as xs:boolean db:exists($db as xs:string, $path as xs:string) as xs:boolean
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Summary | Checks if the specified database or resource exists. Returns false if a database directory is specified.
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db:is-raw
Signatures | db:is-raw($db as xs:string, $path as xs:string) as xs:boolean
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Summary | Checks if the specified resource exists and if it is a raw file. |
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db:is-xml
Signatures | db:is-xml($db as xs:string, $path as xs:string) as xs:boolean
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Summary | Checks if the specified resource exists and if it is an XML document. |
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