171 DBMS_XMLQUERY

DBMS_XMLQUERY provides database-to-XMLType functionality. Whenever possible, use DBMS_XMLGEN, a built-in package in C, instead of DBMS_XMLQUERY.

Using DBMS_XMLQUERY

Constants

Types

Constants

Table 171-1 Constants of DBMS_XMLQUERY

Constant	Description
`DB_ENCODING`	Used to signal that the DB character encoding is to be used.
`DEFAULT_ROWSETTAG`	The tag name for the element enclosing the XML generated from the result set (that is, for most cases the root node tag name) -- `ROWSET`.
`DEFAULT_ERRORTAG`	The default tag to enclose raised errors -- `ERROR`.
`DEFAULT_ROWIDATTR`	The default name for the cardinality attribute of XML elements corresponding to `db.records` -- `NUM`
`DEFAULT_ROWTAG`	The default tag name for the element corresponding to `db. records` -- `ROW`
`DEFAULT_DATE_FORMAT`	Default date mask `--'MM/dd/yyyy HH:mm:ss'`
`ALL_ROWS`	Indicates that all rows are needed in the output.
`NONE`	Used to specifies that the output should not contain any XML metadata (for example, no DTD).
`DTD`	Used to specify that the generation of the DTD is desired.
`SCHEMA`	Used to specify that the generation of the XML Schema is desired.
`LOWER_CASE`	Use lower case tag names.
`UPPER_CASE`	Use upper case tag names.

Types

Table 171-2 Types of DBMS_XMLQUERY

Type	Description
`ctxType`	The type of the query context handle. This is the return type of NEWCONTEXT

Summary of DBMS_XMLQUERY Subprograms

Table 171-3 DBMS_XMLQUERY Package Subprograms

Method	Description
CLOSECONTEXT	Closes or deallocates a particular query context.
GETDTD	Generates the DTD.
GETEXCEPTIONCONTENT	Returns the thrown exception's error code and error message.
GETNUMROWSPROCESSED	Returns the number of rows processed for the query.
GETVERSION	Prints the version of the XSU in use.
GETXML	Generates the XML document.
NEWCONTEXT	Creates a query context and it returns the context handle.
PROPAGATEORIGINALEXCEPTION	Tells the XSU that if an exception is raised, and is being thrown, the XSU should throw the very exception raised; rather then, wrapping it with an `OracleXMLSQLException`.
REMOVEXSLTPARAM	Removes a particular top-level stylesheet parameter.
SETBINDVALUE	Sets a value for a particular bind name.
SETCOLLIDATTRNAME	Sets the name of the id attribute of the collection element's separator tag.
SETDATAHEADER	Sets the XML data header.
SETDATEFORMAT	Sets the format of the generated dates in the XML document.
SETENCODINGTAG	Sets the encoding processing instruction in the XML document.
SETERRORTAG	Sets the tag to be used to enclose the XML error documents.
SETMAXROWS	Sets the maximum number of rows to be converted to XML.
SETMETAHEADER	Sets the XML meta header.
SETRAISEEXCEPTION	Tells the XSU to throw the raised exceptions.
SETRAISENOROWSEXCEPTION	Tells the XSU to throw or not to throw an `OracleXMLNoRowsException` in the case when for one reason or another, the XML document generated is empty.
SETROWIDATTRNAME	Sets the name of the id attribute of the row enclosing tag.
SETROWIDATTRVALUE	Specifies the scalar column whose value is to be assigned to the id attribute of the row enclosing tag.
SETROWSETTAG	Sets the tag to be used to enclose the XML dataset.
SETROWTAG	Sets the tag to be used to enclose the XML element.
SETSKIPROWS	Sets the number of rows to skip.
SETSQLTOXMLNAMEESCAPING	This turns on or off escaping of XML tags in the case that the SQL object name, which is mapped to a XML identifier, is not a valid XML identifier.
SETSTYLESHEETHEADER	Sets the stylesheet header.
SETTAGCASE	Specified the case of the generated XML tags.
SETXSLT	Registers a stylesheet to be applied to generated XML.
SETXSLTPARAM	Sets the value of a top-level stylesheet parameter.
USENULLATTRIBUTEINDICATOR	Specifies weather to use an XML attribute to indicate `NULL`ness.
USETYPEFORCOLLELEMTAG	Tells the XSU to use the collection element's type name as the collection element tag name.

CLOSECONTEXT

Closes or deallocates a particular query context

Syntax

PROCEDURE CLOSECONTEXT(
ctxHdl IN ctxType);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.

GETDTD

Generates and returns the DTD based on the SQL query used to initialize the context. The options are described in the following table.

Syntax Description

Syntax	Description
`FUNCTION GETDTD(` `ctxHdl IN ctxType,` `withVer IN BOOLEAN := false)` `RETURN CLOB;`	Function that generates the DTD based on the SQL query used to initialize the context.
`PROCEDURE GETDTD(` `ctxHdl IN ctxType,` `xDoc IN CLOB,` `withVer IN BOOLEAN := false);`	Procedure that generates the DTD based on the SQL query used to initialize the context; specifies the output `CLOB` for XML document result.

FUNCTION GETDTD(

ctxHdl IN ctxType,

withVer IN BOOLEAN := false)

RETURN CLOB;

Function that generates the DTD based on the SQL query used to initialize the context.

PROCEDURE GETDTD(

ctxHdl IN ctxType,

xDoc IN CLOB,

withVer IN BOOLEAN := false);

Procedure that generates the DTD based on the SQL query used to initialize the context; specifies the output CLOB for XML document result.

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`withVer`	`(IN)`	Generate the version information? `TRUE` for yes`.`
`xDoc`	`(IN)`	`CLOB` into which to write the generated XML document.

GETEXCEPTIONCONTENT

Returns the thrown exception's SQL error code and error message through the procedure's OUT parameters. This procedure is a work around the JVM functionality that obscures the original exception by its own exception, rendering PL/SQL unable to access the original exception content.

Syntax

PROCEDURE GETEXCEPTIONCONTENT(
ctxHdl IN ctxType,
errNo OUT NUMBER,
errMsg OUT VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`errNo`	`(OUT)`	Error number.
`errMsg`	`(OUT)`	Error message.

GETNUMROWSPROCESSED

Return the number of rows processed for the query.

Syntax

FUNCTION GETNUMROWSPROCESSED(
ctxHdl IN ctxType)
RETURN NUMBER;

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.

GETVERSION

Prints the version of the XSU in use.

Syntax

PROCEDURE GETVERSION();

GETXML

Creates the new context, executes the query, gets the XML back and closes the context. This is a convenience function. The context doesn't have to be explicitly opened or closed. The options are described in the following table.

Syntax	Description
`FUNCTION GETXML(` `sqlQuery IN VARCHAR2,` `metaType IN NUMBER := NONE)` `RETURN CLOB;`	This function uses a SQL query in string form.
`FUNCTION GETXML(` `sqlQuery IN CLOB,` `metaType IN NUMBER := NONE)` `RETURN CLOB;`	This function uses a SQL query in `CLOB` form.
`FUNCTION GETXML(` `ctxHdl IN ctxType,` `metaType IN NUMBER := NONE)` `RETURN CLOB;`	This function generates the XML document based on a SQL query used to initialize the context.
`PROCEDURE GETXML(` `ctxHdl IN ctxType,` `xDoc IN CLOB,` `metaType IN NUMBER := NONE);`	This procedure generates the XML document based on the SQL query used to initialize the context.

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`metaType`	`(IN)`	XML metadata type (`NONE`, `DTD`, or `SCHEMA`).
`sqlQuery`	`(IN)`	SQL query.
`xDoc`	`(IN)`	`CLOB` into which to write the generated XML document.

NEWCONTEXT

Creates a query context and it returns the context handle. The options are described in the following table.

Syntax Description

Syntax	Description
`FUNCTION NEWCONTEXT(` `sqlQuery IN VARCHAR2)` `RETURN ctxType;`	Creates a query context from a string.
`FUNCTION NEWCONTEXT(` `sqlQuery IN CLOB)` `RETURN ctxType;`	Creates a query context from a `CLOB`.

FUNCTION NEWCONTEXT(

sqlQuery IN VARCHAR2)

RETURN ctxType;

Creates a query context from a string.

FUNCTION NEWCONTEXT(

sqlQuery IN CLOB)

RETURN ctxType;

Creates a query context from a CLOB.

Parameter	IN / OUT	Description
`sqlQuery`	`(IN)`	SQL query, the results of which to convert to XML.

PROPAGATEORIGINALEXCEPTION

Specifies whether to throw every original exception raised or to wrap it in an OracleXMLSQLException.

Syntax

PROCEDURE PROPAGATEORIGINALEXCEPTION(
ctxHdl IN ctxType,
flag IN BOOLEAN);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`flag`	`(IN)`	`TRUE` if want to propagate original exception, `FALSE` to wrap in `OracleXMLException.`

REMOVEXSLTPARAM

Removes the value of a top-level stylesheet parameter. If no stylesheet is registered, this method is not operational.

Syntax

PROCEDURE REMOVEXSLTPARAM(
ctxHdl IN ctxType,
name IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`name`	`(IN)`	Name of the top level stylesheet parameter.

SETBINDVALUE

Sets a value for a particular bind name.

Syntax

PROCEDURE SETBINDVALUE(
ctxHdl IN ctxType,
bindName IN VARCHAR2,
bindValue IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`bindName`	`(IN)`	Bind name.
`bindValue`	`(IN)`	Bind value.

SETCOLLIDATTRNAME

Sets the name of the id attribute of the collection element's separator tag. Passing NULL or an empty string for the tag causes the row id attribute to be omitted.

Syntax

PROCEDURE SETCOLLIDATTRNAME(
ctxHdl IN ctxType,
attrName IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`attrName`	`(IN)`	Attribute name.

SETDATAHEADER

Sets the XML data header. The data header is an XML entity that is appended at the beginning of the query-generated XML entity, the rowset. The two entities are enclosed by the docTag argument. The last data header specified is used. Passing in NULL for the header parameter unsets the data header.

Syntax

PROCEDURE SETDATAHEADER(
ctxHdl IN ctxType,
header IN CLOB := null,
tag IN VARCHAR2 := null);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`header`	`(IN)`	Header.
`tag`	`(IN)`	Tag used to enclose the data header and the rowset.

SETDATEFORMAT

Sets the format of the generated dates in the XML document. The syntax of the date format pattern, the date mask, should conform to the requirements of the java.text.SimpleDateFormat class. Setting the mask to NULL or an empty string sets the default mask -- DEFAULT_DATE_FORMAT.

Syntax

PROCEDURE SETDATEFORMAT(
ctxHdl IN ctxType,
mask IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`mask`	`(IN)`	The date mask.

SETENCODINGTAG

Sets the encoding processing instruction in the XML document.

Syntax

PROCEDURE SETENCODINGTAG(
ctxHdl IN ctxType,
enc IN VARCHAR2 := DB_ENCODING);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`enc`	`(IN)`	The encoding to use.

SETERRORTAG

Sets the tag to be used to enclose the XML error documents.

Syntax

PROCEDURE SETERRORTAG(
ctxHdl IN ctxType,
tag IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`tag`	`(IN)`	Tag name.

SETMAXROWS

Sets the maximum number of rows to be converted to XML. By default, there is no set maximum.

Syntax

PROCEDURE SETMAXROWS (
ctxHdl IN ctxType,
rows IN NUMBER);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`rows`	`(IN)`	Maximum number of rows to generate.

SETMETAHEADER

Sets the XML meta header. When set, the header is inserted at the beginning of the metadata part (DTD or XMLSchema) of each XML document generated by this object. The last meta header specified is used. Passing in NULL for the header parameter unsets the meta header.

Syntax

PROCEDURE SETMETAHEADER(
ctxHdl IN ctxType, 
header IN CLOB := null);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`Header`	`(IN)`	Header.

SETRAISEEXCEPTION

Specifies whether to throw raised exceptions. If this call isn't made or if FALSE is passed to the flag argument, the XSU catches the SQL exceptions and generates an XML document from the exception message.

Syntax

PROCEDURE SETRAISEEXCEPTION(
ctxHdl IN ctxType,
flag IN BOOLEAN:=true);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`flag`	`(IN)`	Throw raised exceptions? `TRUE` for yes, otherwise `FALSE.`

SETRAISENOROWSEXCEPTION

Specifies whether to throw an OracleXMLNoRowsException when the generated XML document is empty. By default, the exception is not thrown.

Syntax

PROCEDURE SETRAISENOROWSEXCEPTION(
ctxHdl IN ctxType,
flag IN BOOLEAN:=false);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`flag`	`(IN)`	Throws an `OracleXMLNoRowsException` if set to `TRUE`.

SETROWIDATTRNAME

Sets the name of the id attribute of the row enclosing tag. Passing NULL or an empty string for the tag causes the row id attribute to be omitted.

Syntax

PROCEDURE SETROWIDATTRNAME(
ctxHdl IN ctxType,
attrName IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`attrName`	`(IN)`	Attribute name.

SETROWIDATTRVALUE

Specifies the scalar column whose value is to be assigned to the id attribute of the row enclosing tag. Passing NULL or an empty string for the colName assigns the row count value (0, 1, 2 and so on) to the row id attribute.

Syntax

PROCEDURE SETROWIDATTRVALUE(
ctxHdl IN ctxType,
colName IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`colName`	`(IN)`	Column whose value is to be assigned to the row id attribute.

SETROWSETTAG

Sets the tag to be used to enclose the XML dataset.

Syntax

PROCEDURE SETROWSETTAG(
ctxHdl IN ctxType,
tag IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`tag`	`(IN)`	Tag name.

SETROWTAG

Sets the tag to be used to enclose the XML element corresponding to a db.record.

Syntax

PROCEDURE SETROWTAG(
ctxHdl IN ctxType,
tag IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`tag`	`(IN)`	Tag name.

SETSKIPROWS

Sets the number of rows to skip. By default, 0 rows are skipped.

Syntax

PROCEDURE SETSKIPROWS(
ctxHdl IN ctxType,
rows IN NUMBER);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`rows`	`(IN)`	Maximum number of rows to skip.

SETSQLTOXMLNAMEESCAPING

This turns on or off escaping of XML tags in the case that the SQL object name, which is mapped to a XML identifier, is not a valid XML identifier.

Syntax

PROCEDURE SETSQLTOXMLNAMEESCAPING(
ctxHdl IN ctxType,
flag IN BOOLEAN := true);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`flag`	`(IN)`	Turn on escaping? `TRUE` for yes, otherwise `FALSE.`

SETSTYLESHEETHEADER

Sets the stylesheet header (the stylesheet processing instructions) in the generated XML document. Passing NULL for the uri argument will unset the stylesheet header and the stylesheet type.

Syntax

PROCEDURE SETSTYLESHEETHEADER(
ctxHdl IN ctxType,
uri IN VARCHAR2,
type IN VARCHAR2 := 'text/xsl');

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`uri`	`(IN)`	Stylesheet URI.
`type`	`(IN)`	Stylesheet type; defaults to "`text/xsl`".

SETTAGCASE

Specifies the case of the generated XML tags.

Syntax

PROCEDURE SETTAGCASE(
ctxHdl IN ctxType,
tCase IN NUMBER);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`tCase`	`(IN)`	The tag's case: 0 for as are 1 for lower case 2 for upper case

SETXSLT

Registers a stylesheet to be applied to generated XML. If a stylesheet was already registered, it is replaced by the new one. The options are described in the following table. Passing NULL for the uri argument or an empty string for the stylesheet argument will unset the stylesheet header and type.

Syntax Description

Syntax	Description
`PROCEDURE SETXSLT(` `ctxHdl IN ctxType,` `uri IN VARCHAR2,` `ref IN VARCHAR2 := null);`	To un-register the stylesheet pass in a null for the uri.
`PROCEDURE SETXSLT(` `ctxHdl IN ctxType,` `stylesheet CLOB,` `ref IN VARCHAR2 := null);`	To un-register the stylesheet pass in a null or an empty string for the stylesheet.

PROCEDURE SETXSLT(

ctxHdl IN ctxType,

uri IN VARCHAR2,

ref IN VARCHAR2 := null);

To un-register the stylesheet pass in a null for the uri.

PROCEDURE SETXSLT(

ctxHdl IN ctxType,

stylesheet CLOB,

ref IN VARCHAR2 := null);

To un-register the stylesheet pass in a null or an empty string for the stylesheet.

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`uri`	`(IN)`	Stylesheet URI.
`stylesheet`	`(IN)`	Stylesheet.
`ref`	`(IN)`	URL to include, imported and external entities.

SETXSLTPARAM

Sets the value of a top-level stylesheet parameter. The parameter value is expected to be a valid XPath expression; the string literal values would therefore have to be quoted explicitly. If no stylesheet is registered, this method is not operational.

Syntax

PROCEDURE SETXSLTPARAM(
ctxHdl IN ctxType,
name IN VARCHAR2,
value IN VARCHAR2);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`name`	`(IN)`	Name of the top level stylesheet parameter.
`value`	`(IN)`	Value to be assigned to the stylesheet parameter.

USENULLATTRIBUTEINDICATOR

Specifies whether to use an XML attribute to indicate NULLness, or to do this by omitting the particular entity in the XML document.

Syntax

PROCEDURE SETNULLATTRIBUTEINDICATOR(
ctxHdl IN ctxType, 
flag IN BOOLEAN);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`flag`	`(IN)`	Sets attribute to `NULL` if `TRUE`, omits from XML document if `FALSE`.

USETYPEFORCOLLELEMTAG

Specifies whether to use the collection element's type name as its element tag name. By default, the tag name for elements of a collection is the collection's tag name followed by _item.

Syntax

PROCEDURE USETYPEFORCOLLELEMTAG(
ctxHdl IN ctxType,
flag IN BOOLEAN := true);

Parameter	IN / OUT	Description
`ctxHdl`	`(IN)`	Context handle.
`flag`	`(IN)`	Turn on use of the type name?