Changes

This [[Module Library|XQuery Module]] contains functions to access relational databases from XQuery using SQL. With this module, you can execute query, update and prepared statements, and the result sets are returned as sequences of XML elements representing tuples. Each element has children representing the columns returned by the SQL statement. This module uses JDBC to connect to a SQL server. Hence, your JDBC driver will need to be added to the classpath, too. If you work with the full distributions of BaseX, you can copy the driver into the {{Code|lib}} directory. To connect to MySQL, for example, download the [https://dev.mysql.com/downloads/connector/j/ Connector/J Driver] and extract the archive into this directory. =Conventions= {{Mark|Updated with Version 9.0}}: All functions and errors in this module are assigned to the <code><nowiki>http://basex.org/modules/sql</nowiki></code> namespace, which is statically bound to the {{Code|sql}} prefix.<br/> =Functions= ==sqlxquery:initeval==

|{{Func|sqlxquery:initeval|$class query as xs:string|empty-sequenceitem()*}}<br />{{Func|xquery:eval|$query as xs:string, $bindings as map(*)?|item()*}}<br />{{Func|xquery:eval|$query as xs:string, $bindings as map(*)?, $options as map(*)?|item()*}}<br />

|This function initializes a JDBC driver specified via Evaluates the supplied {{Code|$classquery}}string as XQuery expression and returns the resulting items. This step might <br/>The evaluated query has its own query context. If a returned node is stored in a database, a main-memory copy will be superfluous if returned as result, because the SQL referenced database is closed after query execution and will not embeddedbe accessible anymore.<br/ >Variables and context items can be declared via {{Code|$bindings}}. The specified keys must be QNames or strings:* If a key is a QName, it will be directly adopted as variable name.* It a key is a string, it may be prefixed with a dollar sign. Namespace can be specified using the [http://www.jclark.com/xml/xmlns.htm Clark Notation].* If the specified string is empty, the value will be bound to the context item.The {{Code|$options}} parameter contains evaluation options:* {{Code|permission}}: the query will be evaluated with the specified permissions (see [[User Management]]).* {{Code|timeout}}: query execution will be interrupted after the specified number of seconds.* {{Code|memory}}: query execution will be interrupted if the specified number of megabytes will be exceeded. This check works best if only one process is running at the same time. Moreover, please note that this option enforces garbage collection, so it will take some additional time, and it requires GC to be enabled in your JVM.* {{Code|base-uri}}: set [https://www.w3.org/TR/xquery-31/#dt-static-base-uri base-uri property] for the query. This URI will be used when resolving relative URIs by functions such as {{Code|fn:doc}}.* {{Code|pass}}: passes on the original error info (line and column number, optional file uri). By default, this option is {{Code|false}}.

|{{Error|initupdate|XQuery Errors#SQL Functions Errors}} the specified driver is not foundquery contains [[XQuery Update#Updating Expressions|updating expressions]].|} ==sql:connect== {| width='100%'|-| width='120' | '''Signatures'''|{{Func|sql:connect|$url as xs:string|xs:anyURI}}<br/ >{{FuncError|sql:connectpermission|$url as xs:string, $user as xs:string, $password as xs:string|xs:anyURI#Errors}}insufficient permissions for evaluating the query.<br/ >{{FuncError|sql:connecttimeout|$url as xs:string, $user as xs:string, $password as xs:string, $options as map(*)|xs:anyURI#Errors}}query execution exceeded timeout.<br/ >|-| '''Summary'''|This function establishes a connection to a relational database and returns a connection id. The parameter {{CodeError|$urllimit|#Errors}} is the URL of the database and shall be of the form: {{Code|jdbc:query execution exceeded memory limit.<driver name>:[br//<server>[/<database>]]}}. If the parameters {{Code|$user}} and {{Code|$password}} are specified, they are used as credentials for connecting to the database. The {{Code|$options}} parameter can be used to set connection options.|-| '''Errors'''|{{Error|errornested|XQuery Errors#SQL Functions Errors}} an SQL exception occurs, enested query evaluation is not allowed.g. missing JDBC driver or not existing relation<br/>Any other error that may occur while evaluating the query.

|Connects to an SQL Server and sets autocommit to * {{Code|xquery:eval("1+3")}} returns {{Code|true4}}.<br />* You can bind the context and e.g. operate on a certain database only:<br /><pre class="'brush:xquery"'>sqlxquery:connecteval('dbc:sqlserver:"//DBServer'country", map { 'autocommit': truedb:open('factbook') })

|* The following expressions use strings as keys. All of them return 'XML':<br/><pre class='brush:xquery'>xquery:eval(".", map { '': 'XML' }),

==sqlxquery:execute==eval("declare variable $xml external; $xml", map { 'xml': 'XML' }),

{{Mark|Updated with Version 9.0}}xquery: Return update count for updating statements. {{Code|$options}} argument added.eval( {| width='100%'|-| width "declare namespace pref='120' | '''Signatures''URI';|{{Func|sql:execute|$id as xs:anyURI, declare variable $statement as xspref:string|item()*}}<br/>{{Func|sql:execute|$id as xs:anyURI, $statement as xs:string, $options as map(*)|item()*}}|-| '''Summary'''xml external;| This function executes an SQL {{Code| $statement}}, using the connection with the specified {{Code|$id}}. The returned result depends on the kind of statementpref:* If an update statement was executedxml", the number of updated rows will be returned as integer.* Otherwise, an XML representation of all results will be returned.With { map {Code|$options}}, the following parameter can be set:* {{Code|timeout}}: query execution will be interrupted after the specified number of seconds.|-| '''Errors'''|{{Error|error|XQuery Errors#SQL Functions Errors}} an SQL exception occurs, e.g. not existing relation is retrieved.<br/ >{{Error|id|XQuery Errors#SQL Functions ErrorsURI}} the specified connection does not exist.<br/ >|} ==sql:execute-prepared== {{Mark|Updated with Version 9.0}}: Return update count for updating statements. {| width='100%'|-| width='120' | xml'''Signatures'''|{{Func|sql:execute-prepared|$id as xs:anyURI, $params as element(sql:parameters)|item()*}}<br/>{{Func|sql:execute-prepared|$id as xs:anyURI, $params as element(sql:parameters), $options as map(*)|item()*}}|-| ''XML'Summary'''| This function executes a prepared statement:* The output format is identical to [[#sql:execute|sql:execute]].* The parameter {{Code|$id}} refers to the prepared statement.* The optional parameter {{Code|$params}} is an element {{Code|<sql:parameters/>}} representing the parameters for a prepared statement along with their types and values. The following schema shall be used:<br/ >With {{Code|$options}}, the following parameter can be set:* {{Code|timeout}}: query execution will be interrupted after the specified number of seconds.<pre class="brush:xquery">element sql:parameters { element sql:parameter { attribute type { "int" | "string" | "boolean" | "date" | "double" | "float" | "short" | "time" | "timestamp" | "sqlxml" }, attribute null { "true" | "false" }?, text }+}?)

|-| '* The following expressions use QNames as keys. All of them return 'XML'Errors'''|{{Error|attribute|XQuery Errors#SQL Functions Errors}} an attribute different from {{Code|type}} and {{Code|null}} is set for a {{Code|<sql:parameter/>}} element.<br/ >{{Error|error|XQuery Errors#SQL Functions Errors}} an SQL exception occurs, e.g. not existing relation is retrieved.<br/ >{{Error|id|XQuery Errors#SQL Functions Errors}} the specified connection does not exist.<br/ >{{Error|parameters|XQuery Errors#SQL Functions Errors}} wrong number of {{Code|<sql:parameter/>}} elements, or parameter type is not specified.<br/>{{Error|type|XQuery Errors#SQL Functions Errors}} the value of a parameter cannot be converted to the specified format.|} ==sql:prepare== {| width='100%'|-| widthpre class='120' | '''Signatures'''|{{Func|sql:prepare|$id as xs:anyURI, $statement as xs:string|xs:anyURI}}|-| '''Summary'''|This function prepares an SQL {{Code|$statement}}, using the specified connection {{Code|$id}}, and returns the id reference to this statement. The statement is a string with one or more '?' placeholders. If the value of a field has to be set to {{Code|NULL}}, then the attribute {{Code|null}} of the {{Code|<sqlbrush:parameter/>}} element must be {{Code|true}}.|-| '''Errors''xquery'|{{Error|error|XQuery Errors#SQL Functions Errors}} an SQL exception occurs.<br/ >{{Error|id|XQuery Errors#SQL Functions Errors}} the specified connection does not exist.<br/ >|} ==sql:commit== {| width='100%'|-| widthdeclare namespace pref ='120URI' | '''Signatures'''|{{Func|sql:commit|$id as xs:anyURI|empty-sequence()}}|-| '''Summary'''| This function commits the changes made to a relational database, using the specified connection {{Code|$id}}.|-| '''Errors'''|{{Error|error|XQuery Errors#SQL Functions Errors}} an SQL exception occurs.<br/ >{{Error|id|XQuery Errors#SQL Functions Errors}} the specified connection does not exist.<br/ >|};

==sqlxquery:rollback==eval("declare variable $xml external; $xml", map { xs:QName('xml'): 'XML' }),

{| width='100%'|-| width='120' | '''Signatures'''|{{Func|sql:rollback|let $id as xsquery :anyURI|empty-sequence()}}|-| '''Summary'''| This function rolls back the changes made to a relational database, using the specified connection {{Code|$id}}.|-| '''Errors'''|{{Error|error|XQuery Errors#SQL Functions Errors}} an SQL exception occurs.<br/ >{{Error|id|XQuery Errors#SQL Functions Errors}} the specified connection does not exist.<br/ >|} ==sql:close== {| width"declare namespace pref='100%URI';|-| width='120' | '''Signatures'''|{{Func|sql:close| declare variable $id as xspref:anyURI|empty-sequence()}}xml external;|-| '''Summary'''| This function closes a database connection with the specified {{Code| $id}}.<br/>Opened connections will automatically be closed after the XQuery expression has been evaluated, but in order to save memory, it is always recommendable to close connections that are not used anymore.|-| '''Errors'''|{{Error|error|XQuery Errors#SQL Functions Errors}} an SQL exception occurs.<br/ >{{Error|id|XQuery Errors#SQL Functions Errors}} the specified connection does not exist.<br/ >|} =Examples= ==Direct queries== A simple select statement can be executed as followspref: <pre class="brush:xqueryxml">let $id vars := sqlmap { xs:connectQName("jdbc:postgresql://localhost:5432/coffeehouse")return sql:execute($id, "SELECT * FROM coffees WHERE price < 10")</pre> The result may look like: <pre class="brush'pref:xml"><sql:row xmlns:sql="http://basex.org/modules/sql"> <sql:column name="cof_name">French_Roast</sql:column> <sql:column name="sup_id">49</sql:column> <sql:column name="price">9.5</sql:column> <sql:column name="sales">15</sql:column> <sql:column name="total">30</sql:column></sql:row><sql:row xmlns:sql="http://basex.org/modules/sql"> <sql:column name="cof_name">French_Roast_Decaf</sql:column> <sql:column name="sup_id">49</sql:column> <sql:column name="price">7.5</sql:column> <sql:column name="sales">10</sql:column> <sql:column name="total">14</sql:column></sql:row></pre> ==Prepared Statements== A prepared select statement can be executed in the following way: <pre class="brush:xquery">(: Establish a connection :)let $conn := sql:connect("jdbc:postgresql://localhost:5432/coffeehouse")(: Obtain a handle to a prepared statement :)let $prep := sql:prepare($conn, "SELECT * FROM coffees WHERE price < ? AND cof_name = ?"')(: Values and types of prepared statement parameters :)let $params := <sql:parameters> <sql:parameter type='doubleXML'>10</sql:parameter> <sql:parameter type='string'>French_Roast</sql:parameter> </sql:parameters>(: Execute prepared statement :)}return sqlxquery:execute-preparedeval($prepquery, $paramsvars)

|{{Func|xquery:eval-update|$query as xs:string|item()*}}<br />{{Func|xquery:eval-update|$query as xs:string, $bindings as map(*)?|item()*}}<br />{{Func|xquery:eval-update|$query as xs:string, $bindings as map(*)?, $options as map(xs:string, xs:string*)?|item()}}<br />

|{{Func|xquery:invoke|$uri as xs:string|item()*}}<br />{{Func|xquery:invoke|$uri as xs:string, $bindings as map(*)?|item()*}}<br />{{Func|xquery:invoke|$uri as xs:string, $bindings as map(*)?, $options as map(*)?|item()*}}<br />

|{{Error|update|#Errors}} the expression contains [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|permission|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|BXXQ0004timeout|#Errors}} query execution exceeded timeout.<br/>{{Error|nested|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query.

|{{Func|xquery:invoke-update|$uri as xs:string|item()*}}<br />{{Func|xquery:invoke-update|$uri as xs:string, $bindings as map(*)?|item()*}}<br />{{Func|xquery:invoke-update|$uri as xs:string, $bindings as map(*)?, $options as map(*)?|item()*}}<br />

|{{Error|update|#Errors}} the expression contains no [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|permission|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|BXXQ0004timeout|#Errors}} query execution exceeded timeout.<br/>{{Error|nested|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query.

|{{Func|xquery:parse|$query as xs:string|item()?}}<br />{{Func|xquery:parse|$query as xs:string, $options as map(*)?|item()?}}<br />

|{{Func|xquery:parse-uri|$uri as xs:string|item()?}}<br />{{Func|xquery:parse-uri|$uri as xs:string, $options as map(*)?|item()?}}<br />

* Added: [[#xquery:invoke-uriupdate|xquery:invoke-uriupdate]]