7.290 XMLPI

Syntax

Purpose

XMLPI generates an XML processing instruction using identifier and optionally the evaluated result of value_expr. A processing instruction is commonly used to provide to an application information that is associated with all or part of an XML document. The application uses the processing instruction to determine how best to process the XML document.

You must specify a value for Oracle Database to use an the enclosing tag. You can do this by specifying identifier, which is a string literal, or by specifying EVALNAME value_expr. In the latter case, the value expression is evaluated and the result, which must be a string literal, is used as the identifier. The identifier does not have to be a column name or column reference. It cannot be an expression or null. It can be up to 4000 characters if the initialization parameter MAX_STRING_SIZE = STANDARD, and 32767 characters if MAX_STRING_SIZE = EXTENDED. See "Extended Data Types" for more information.

The optional value_expr must resolve to a string. If you omit the optional value_expr, then a zero-length string is the default. The value returned by the function takes this form:

<?identifier string?>

XMLPI is subject to the following restrictions:

  • The identifier must be a valid target for a processing instruction.

  • You cannot specify xml in any case combination for identifier.

  • The identifier cannot contain the consecutive characters ?>.

See Also:

Oracle XML DB Developer's Guide for more information on this function

Examples

The following statement uses the DUAL table to illustrate the use of the XMLPI syntax:

SELECT XMLPI(NAME "Order analysisComp", 'imported, reconfigured, disassembled')
   AS "XMLPI" FROM DUAL;
 
XMLPI
--------------------------------------------------------------------------------
<?Order analysisComp imported, reconfigured, disassembled?>