XMLCOLATTVAL

XMLCOLATTVAL

Syntax

XMLColAttVal::=

Purpose

XMLColAttVal creates an XML fragment and then expands the resulting XML so that each XML fragment has the name "column" with the attribute "name". You can use the AS c_alias clause to change the value of the name attribute to something other than the column name.

You must specify a value for value_expr. If value_expr is null, then no element is returned.

Restriction on XMLColAttVal You cannot specify an object type column for value_expr.

Examples

The following example creates an Emp element for a subset of employees, with nested employee_id, last_name, and salary elements as the contents of Emp. Each nested element is named column and has a name attribute with the column name as the attribute value:

SELECT XMLELEMENT("Emp",

XMLCOLATTVAL(e.employee_id, e.last_name, e.salary)) "Emp Element" FROM employees e

WHERE employee_id = 204;

Emp Element

--------------------------------------------------------------------

<Emp>

<column name="EMPLOYEE_ID">204</column> <column name="LAST_NAME">Baer</column> <column name="SALARY">10000</column>

</Emp>

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XMLCONCAT

See Also: the example for XMLFOREST on page 6-217 to compare the output of these two functions

XMLCONCAT

Syntax

XMLConcat::=

Purpose

XMLConcat takes as input a series of XMLType instances, concatenates the series of elements for each row, and returns the concatenated series. XMLConcat is the inverse of XMLSequence.

Null expressions are dropped from the result. If all the value expressions are null, then the function returns null.

See Also: XMLSEQUENCE on page 6-218

Examples

The following example creates XML elements for the first and last names of a subset of employees, and then concatenates and returns those elements:

SELECT XMLCONCAT(XMLELEMENT("First", e.first_name),

XMLELEMENT("Last", e.last_name)) AS "Result"

FROM employees e

WHERE e.employee_id > 202;

Result

----------------------------------------------------------------

<First>Susan</First>

<Last>Mavris</Last>

<First>Hermann</First>

<Last>Baer</Last>

<First>Shelley</First>

<Last>Higgins</Last>

Functions 6-213

XMLELEMENT

<First>William</First>

<Last>Gietz</Last>

4 rows selected.

XMLELEMENT

Syntax

XMLElement::=

XML_attributes_clause::=

Purpose

XMLElement takes an element name for identifier, an optional collection of attributes for the element, and arguments that make up the element’s content. It returns an instance of type XMLType. XMLElement is similar to SYS_XMLGen except that XMLElement can include attributes in the XML returned, but it does not accept formatting using the XMLFormat object.

The XMLElement function is typically nested to produce an XML document with a nested structure, as in the example in the following section.

You must specify a value for identifier, which Oracle uses as the enclosing tag. The identifier does not have to be a column name or column reference. It cannot be an expression or null.

In the XML_attributes_clause, if the value_expr is null, then no attribute is created for that value expression. The type of value_expr cannot be an object type or collection.

The objects that make up the element content follow the XMLATTRIBUTES keyword.

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XMLELEMENT

■If value_expr is a scalar expression, then you can omit the AS clause, and Oracle uses the column name as the element name.

■If value_expr is an object type or collection, then the AS clause is mandatory, and Oracle uses the specified c_alias as the enclosing tag.

■If value_expr is null, then no element is created for that value expression.

See Also: SYS_XMLGEN on page 6-166

Examples

The following example produces an Emp element for a series of employees, with nested elements that provide the employee’s name and hire date:

SELECT XMLELEMENT("Emp", XMLELEMENT("Name", e.job_id||’ ’||e.last_name), XMLELEMENT("Hiredate", e.hire_date)) as "Result" FROM employees e WHERE employee_id > 200;

Result

-------------------------------------------------------------------

<Emp>

<Name>MK_MAN Hartstein</Name> <Hiredate>17-FEB-96</Hiredate>

</Emp>

<Emp>

<Name>MK_REP Fay</Name> <Hiredate>17-AUG-97</Hiredate>

</Emp>

<Emp>

<Name>HR_REP Mavris</Name> <Hiredate>07-JUN-94</Hiredate>

</Emp>

<Emp>

<Name>PR_REP Baer</Name> <Hiredate>07-JUN-94</Hiredate>

</Emp>

<Emp>

<Name>AC_MGR Higgins</Name> <Hiredate>07-JUN-94</Hiredate>

</Emp>

Functions 6-215

XMLELEMENT

<Emp>

<Name>AC_ACCOUNT Gietz</Name> <Hiredate>07-JUN-94</Hiredate>

</Emp>

6 rows selected.

The following similar example uses the XMLElement function with the XML_ attributes_clause to create nested XML elements with attribute values for the top-level element:

SELECT XMLELEMENT("Emp",

XMLATTRIBUTES(e.employee_id AS "ID", e.last_name), XMLELEMENT("Dept", e.department_id), XMLELEMENT("Salary", e.salary)) AS "Emp Element"

FROM employees e

WHERE e.employee_id = 206;

Emp Element

---------------------------------------------------------------

<Emp ID="206" LAST_NAME="Gietz"> <Dept>110</Dept> <Salary>8300</Salary>

</Emp>

Notice that the AS identifier clause was not specified for the last_name column. As a result, the XML returned uses the column name last_name as the default.

Finally, the next example uses a subquery within the XML_attributes_clause to retrieve information from another table into the attributes of an element:

SELECT XMLELEMENT("Emp", XMLATTRIBUTES(e.employee_id, e.last_name), XMLELEMENT("Dept", XMLATTRIBUTES(e.department_id,

(SELECT d.department_name FROM departments d

WHERE d.department_id = e.department_id) as "Dept_name")), XMLELEMENT("salary", e.salary),

XMLELEMENT("Hiredate", e.hire_date)) AS "Emp Element" FROM employees e

WHERE employee_id = 205;

Emp Element

-------------------------------------------------------------------

<Emp EMPLOYEE_ID="205" LAST_NAME="Higgins">

<Dept DEPARTMENT_ID="110" Dept_name="Accounting"/>

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