Difference between revisions of "SQL Module"
(add JDBC driver information) |
|||
(30 intermediate revisions by the same user not shown) | |||
Line 1: | Line 1: | ||
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 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= | =Conventions= | ||
− | All functions in this module are assigned to the | + | 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= | =Functions= | ||
==sql:init== | ==sql:init== | ||
+ | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
Line 19: | Line 20: | ||
|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|init|#Errors}} the specified driver is not found. |
|} | |} | ||
==sql:connect== | ==sql:connect== | ||
+ | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|sql:connect|$url as xs:string|xs: | + | |{{Func|sql:connect|$url as xs:string|xs:anyURI}}<br/ >{{Func|sql:connect|$url as xs:string, $user as xs:string, $password as xs:string|xs:anyURI}}<br/ >{{Func|sql:connect|$url as xs:string, $user as xs:string, $password as xs:string, $options as map(*)?|xs:anyURI}}<br/ > |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | |This function establishes a connection to a relational database | + | |This function establishes a connection to a relational database and returns a connection id. The parameter {{Code|$url}} is the URL of the database and shall be of the form: {{Code|jdbc:<driver name>:[//<server>[/<database>]]}}. If the parameters {{Code|$user}} and {{Code|$password}} are specified, they are used as credentials for connecting to the database. The {{Code|$options}} parameter can be used to set connection options. |
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|error|#Errors}} an SQL exception occurred when connecting to the database. |
+ | |- | ||
+ | | '''Examples''' | ||
+ | |Connects to an SQL Server and sets autocommit to {{Code|true}}: | ||
+ | <pre class="brush:xquery"> | ||
+ | sql:connect('dbc:sqlserver://DBServer', map { 'autocommit': true() }) | ||
+ | </pre> | ||
|} | |} | ||
==sql:execute== | ==sql:execute== | ||
− | |||
− | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|sql:execute|$ | + | |{{Func|sql:execute|$id as xs:anyURI, $statement as xs:string|item()*}}<br/>{{Func|sql:execute|$id as xs:anyURI, $statement as xs:string, $options as map(*)?|item()*}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | | This function executes | + | | This function executes an SQL {{Code|$statement}}, using the connection with the specified {{Code|$id}}. The returned result depends on the kind of statement: |
+ | * If an update statement was executed, the number of updated rows will be returned as integer. | ||
+ | * Otherwise, an XML representation of all results will be returned. | ||
+ | With {{Code|$options}}, the following parameter can be set: | ||
+ | * {{Code|timeout}}: query execution will be interrupted after the specified number of seconds. | ||
|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|error|#Errors}} an error occurred while executing SQL.<br/ >{{Error|id|#Errors}} the specified connection does not exist.<br/>{{Error|timeout|#Errors}} query execution exceeded timeout.<br/> |
− | {{Error| | ||
|} | |} | ||
Line 68: | Line 66: | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|sql:execute-prepared|$id as xs: | + | |{{Func|sql:execute-prepared|$id as xs:anyURI, $params as element(sql:parameters)|item()*}}<br/>{{Func|sql:execute-prepared|$id as xs:anyURI, $params as element(sql:parameters), $options as map(*)?|item()*}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | | This function executes a prepared statement | + | | This function executes a prepared statement with the specified {{Code|$id}}. The output format is identical to [[#sql:execute|sql:execute]]. The optional parameter {{Code|$params}} is an element {{Code|<sql:parameters/>}} representing the parameters for a prepared statement along with their types and values. The following schema shall be used:<br/ > |
− | <pre class="brush: | + | <pre class="brush:xquery"> |
element sql:parameters { | element sql:parameters { | ||
− | + | element sql:parameter { | |
− | + | attribute type { "int" | "string" | "boolean" | "date" | "double" | | |
− | + | "float" | "short" | "time" | "timestamp" | "sqlxml" }, | |
− | + | attribute null { "true" | "false" }?, | |
+ | text | ||
+ | }+ | ||
+ | }? | ||
</pre> | </pre> | ||
+ | With {{Code|$options}}, the following parameter can be set: | ||
+ | * {{Code|timeout}}: query execution will be interrupted after the specified number of seconds. | ||
|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|attribute|#Errors}} an attribute different from {{Code|type}} and {{Code|null}} is set for a {{Code|<sql:parameter/>}} element.<br/ >{{Error|error|#Errors}} an error occurred while executing SQL.<br/ >{{Error|id|#Errors}} the specified connection does not exist.<br/ >{{Error|parameters|#Errors}} no parameter type specified.<br/>{{Error|timeout|#Errors}} query execution exceeded timeout.<br/>{{Error|type|#Errors}} the value of a parameter cannot be converted to the specified format. |
− | {{ | ||
− | {{ | ||
− | {{Error| | ||
− | {{Error| | ||
− | {{Error| | ||
|} | |} | ||
==sql:prepare== | ==sql:prepare== | ||
+ | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|sql:prepare|$ | + | |{{Func|sql:prepare|$id as xs:anyURI, $statement as xs:string|xs:anyURI}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | |This function prepares | + | |This function prepares an SQL {{Code|$statement}}, using the specified connection {{Code|$id}}, and returns the id reference to this statement. The statement is a string with one or more '?' placeholders. If the value of a field has to be set to {{Code|NULL}}, then the attribute {{Code|null}} of the {{Code|<sql:parameter/>}} element must be {{Code|true}}. |
|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|error|#Errors}} an error occurred while executing SQL.<br/ >{{Error|id|#Errors}} the specified connection does not exist.<br/ > |
− | {{Error| | ||
|} | |} | ||
==sql:commit== | ==sql:commit== | ||
+ | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|sql:commit|$ | + | |{{Func|sql:commit|$id as xs:anyURI|empty-sequence()}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | | This function commits the changes made to a relational database | + | | This function commits the changes made to a relational database, using the specified connection {{Code|$id}}. |
|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|error|#Errors}} an error occurred while executing SQL.<br/ >{{Error|id|#Errors}} the specified connection does not exist.<br/ > |
− | {{Error| | ||
|} | |} | ||
==sql:rollback== | ==sql:rollback== | ||
+ | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|sql:rollback|$ | + | |{{Func|sql:rollback|$id as xs:anyURI|empty-sequence()}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | | This function rolls back the changes made to a relational database | + | | This function rolls back the changes made to a relational database, using the specified connection {{Code|$id}}. |
|- | |- | ||
| '''Errors''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|error|#Errors}} an error occurred while executing SQL.<br/ >{{Error|id|#Errors}} the specified connection does not exist.<br/ > |
− | {{Error| | ||
|} | |} | ||
==sql:close== | ==sql:close== | ||
+ | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|sql:close|$ | + | |{{Func|sql:close|$id as xs:anyURI|empty-sequence()}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | | This function closes a connection | + | | This function closes a database connection with the specified {{Code|$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''' | | '''Errors''' | ||
− | |{{Error| | + | |{{Error|error|#Errors}} an error occurred while executing SQL.<br/ >{{Error|id|#Errors}} the specified connection does not exist.<br/ > |
− | {{Error| | ||
|} | |} | ||
Line 148: | Line 146: | ||
==Direct queries== | ==Direct queries== | ||
− | A simple select statement can be executed | + | |
+ | A simple select statement can be executed as follows: | ||
<pre class="brush:xquery"> | <pre class="brush:xquery"> | ||
− | let $ | + | let $id := sql:connect("jdbc:postgresql://localhost:5432/coffeehouse") |
− | return sql:execute($ | + | return sql:execute($id, "SELECT * FROM coffees WHERE price < 10") |
</pre> | </pre> | ||
− | The result | + | The result may look like: |
<pre class="brush:xml"> | <pre class="brush:xml"> | ||
Line 171: | Line 170: | ||
<sql:column name="sales">10</sql:column> | <sql:column name="sales">10</sql:column> | ||
<sql:column name="total">14</sql:column> | <sql:column name="total">14</sql:column> | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
</sql:row> | </sql:row> | ||
</pre> | </pre> | ||
==Prepared Statements== | ==Prepared Statements== | ||
+ | |||
A prepared select statement can be executed in the following way: | A prepared select statement can be executed in the following way: | ||
Line 192: | Line 184: | ||
(: Values and types of prepared statement parameters :) | (: Values and types of prepared statement parameters :) | ||
let $params := <sql:parameters> | let $params := <sql:parameters> | ||
− | + | <sql:parameter type='double'>10</sql:parameter> | |
− | + | <sql:parameter type='string'>French_Roast</sql:parameter> | |
</sql:parameters> | </sql:parameters> | ||
(: Execute prepared statement :) | (: Execute prepared statement :) | ||
Line 217: | Line 209: | ||
return sql:execute($conn, $q), | return sql:execute($conn, $q), | ||
(: Return table contents :) | (: Return table contents :) | ||
− | sql:execute($conn, "select * from person" | + | sql:execute($conn, "select * from person") |
− | |||
) | ) | ||
</pre> | </pre> | ||
Line 228: | Line 219: | ||
|Description | |Description | ||
|- | |- | ||
− | |{{Code| | + | |{{Code|attribute}} |
− | |An | + | |An attribute different from {{Code|type}} and {{Code|null}} is set for a {{Code|<sql:parameter/>}} element. |
|- | |- | ||
− | |{{Code| | + | |{{Code|error}} |
− | | | + | |An SQL exception occurred. |
|- | |- | ||
− | |{{Code| | + | |{{Code|id}} |
− | | | + | |A connection does not exist. |
|- | |- | ||
− | |{{Code| | + | |{{Code|init}} |
− | | | + | |A database driver is not found. |
|- | |- | ||
− | |{{Code| | + | |{{Code|parameters}} |
− | | | + | |No parameter type specified. |
|- | |- | ||
− | |{{Code| | + | |{{Code|timeout}} |
− | | | + | |Query execution exceeded timeout. |
|- | |- | ||
− | |{{Code| | + | |{{Code|type}} |
− | | | + | |The value of a parameter cannot be converted to the specified format. |
|} | |} | ||
=Changelog= | =Changelog= | ||
+ | |||
+ | ;Version 9.0 | ||
+ | |||
+ | * Updated: [[#sql:execute|sql:execute]], [[#sql:execute-prepared|sql:execute-prepared]]: Return update count for updating statements. {{Code|$options}} argument added. | ||
+ | * Updated: Connection ids are URIs now. | ||
+ | * Updated: error codes updated; errors now use the module namespace | ||
;Version 7.5 | ;Version 7.5 | ||
+ | |||
* Updated: prepared statements are now executed via [[#sql:execute-prepared|sql:execute-prepared]] | * Updated: prepared statements are now executed via [[#sql:execute-prepared|sql:execute-prepared]] | ||
The module was introduced with Version 7.0. | The module was introduced with Version 7.0. | ||
− | |||
− |
Revision as of 13:21, 24 May 2018
This 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 lib
directory. To connect to MySQL, for example, download the Connector/J Driver and extract the archive into this directory.
Contents
Conventions
All functions and errors in this module are assigned to the http://basex.org/modules/sql
namespace, which is statically bound to the sql
prefix.
Functions
sql:init
Signatures | sql:init($class as xs:string) as empty-sequence()
|
Summary | This function initializes a JDBC driver specified via $class . This step might be superfluous if the SQL database is not embedded. |
Errors | init : the specified driver is not found.
|
sql:connect
Signatures | sql:connect($url as xs:string) as xs:anyURI sql:connect($url as xs:string, $user as xs:string, $password as xs:string) as xs:anyURI sql:connect($url as xs:string, $user as xs:string, $password as xs:string, $options as map(*)?) as xs:anyURI |
Summary | This function establishes a connection to a relational database and returns a connection id. The parameter $url is the URL of the database and shall be of the form: jdbc:<driver name>:<server> [/<database>] . If the parameters $user and $password are specified, they are used as credentials for connecting to the database. The $options parameter can be used to set connection options.
|
Errors | error : an SQL exception occurred when connecting to the database.
|
Examples | Connects to an SQL Server and sets autocommit to true :
sql:connect('dbc:sqlserver://DBServer', map { 'autocommit': true() }) |
sql:execute
Signatures | sql:execute($id as xs:anyURI, $statement as xs:string) as item()* sql:execute($id as xs:anyURI, $statement as xs:string, $options as map(*)?) as item()*
|
Summary | This function executes an SQL $statement , using the connection with the specified $id . The returned result depends on the kind of statement:
With
|
Errors | error : an error occurred while executing SQL.id : the specified connection does not exist.timeout : query execution exceeded timeout. |
sql:execute-prepared
Signatures | sql:execute-prepared($id as xs:anyURI, $params as element(sql:parameters)) as item()* sql:execute-prepared($id as xs:anyURI, $params as element(sql:parameters), $options as map(*)?) as item()*
|
Summary | This function executes a prepared statement with the specified $id . The output format is identical to sql:execute. The optional parameter $params is an element <sql:parameters/> representing the parameters for a prepared statement along with their types and values. The following schema shall be used:element sql:parameters { element sql:parameter { attribute type { "int" | "string" | "boolean" | "date" | "double" | "float" | "short" | "time" | "timestamp" | "sqlxml" }, attribute null { "true" | "false" }?, text }+ }? With
|
Errors | attribute : an attribute different from type and null is set for a <sql:parameter/> element.error : an error occurred while executing SQL.id : the specified connection does not exist.parameters : no parameter type specified.timeout : query execution exceeded timeout.type : the value of a parameter cannot be converted to the specified format.
|
sql:prepare
Signatures | sql:prepare($id as xs:anyURI, $statement as xs:string) as xs:anyURI
|
Summary | This function prepares an SQL $statement , using the specified connection $id , and returns the id reference to this statement. The statement is a string with one or more '?' placeholders. If the value of a field has to be set to NULL , then the attribute null of the <sql:parameter/> element must be true .
|
Errors | error : an error occurred while executing SQL.id : the specified connection does not exist. |
sql:commit
Signatures | sql:commit($id as xs:anyURI) as empty-sequence()
|
Summary | This function commits the changes made to a relational database, using the specified connection $id .
|
Errors | error : an error occurred while executing SQL.id : the specified connection does not exist. |
sql:rollback
Signatures | sql:rollback($id as xs:anyURI) as empty-sequence()
|
Summary | This function rolls back the changes made to a relational database, using the specified connection $id .
|
Errors | error : an error occurred while executing SQL.id : the specified connection does not exist. |
sql:close
Signatures | sql:close($id as xs:anyURI) as empty-sequence()
|
Summary | This function closes a database connection with the specified $id .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 : an error occurred while executing SQL.id : the specified connection does not exist. |
Examples
Direct queries
A simple select statement can be executed as follows:
let $id := sql:connect("jdbc:postgresql://localhost:5432/coffeehouse") return sql:execute($id, "SELECT * FROM coffees WHERE price < 10")
The result may look like:
<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>
Prepared Statements
A prepared select statement can be executed in the following way:
(: 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 $params := <sql:parameters> <sql:parameter type='double'>10</sql:parameter> <sql:parameter type='string'>French_Roast</sql:parameter> </sql:parameters> (: Execute prepared statement :) return sql:execute-prepared($prep, $params)
SQLite
The following expression demonstrates how SQLite can be addressed using the Xerial SQLite JDBC driver:
(: Initialize driver :) sql:init("org.sqlite.JDBC"), (: Establish a connection :) let $conn := sql:connect("jdbc:sqlite:database.db") return ( (: Create a new table :) sql:execute($conn, "drop table if exists person"), sql:execute($conn, "create table person (id integer, name string)"), (: Run 10 updates :) for $i in 1 to 10 let $q := "insert into person values(" || $i || ", '" || $i || "')" return sql:execute($conn, $q), (: Return table contents :) sql:execute($conn, "select * from person") )
Errors
Code | Description |
---|---|
attribute
|
An attribute different from type and null is set for a <sql:parameter/> element.
|
error
|
An SQL exception occurred. |
id
|
A connection does not exist. |
init
|
A database driver is not found. |
parameters
|
No parameter type specified. |
timeout
|
Query execution exceeded timeout. |
type
|
The value of a parameter cannot be converted to the specified format. |
Changelog
- Version 9.0
- Updated: sql:execute, sql:execute-prepared: Return update count for updating statements.
$options
argument added. - Updated: Connection ids are URIs now.
- Updated: error codes updated; errors now use the module namespace
- Version 7.5
- Updated: prepared statements are now executed via sql:execute-prepared
The module was introduced with Version 7.0.