PL/SQL DBMS_XMLSTORE.newContext

Oracle PL/SQL provides a package named DBMS_XMLSTORE, which is designed for performing data manipulation operations (DML) directly from XML content. This package is particularly useful when you need to insert, update, or delete rows in a database table based on XML data. The newContext function is a key part of this package, as it initializes a context for XML-based data manipulation in a specified table.

DBMS_XMLSTORE.newContext Overview

The DBMS_XMLSTORE.newContext function creates a context for the XML Store operations targeting a specific database table. This context is then used in subsequent operations (like insert, update, or delete) to apply the XML data to the table.

Syntax

DBMS_XMLSTORE.newContext(tableName IN VARCHAR2) RETURN ctxHandle;

tableName: The name of the database table you want to perform DML operations on, using XML data. A string representing the name of the table for which the context is being created. This table name should be passed as a case-sensitive string if the database is case-sensitive.

RETURN: Returns a context handle (ctxHandle), which is used in further DBMS_XMLSTORE operations.

Example

Here’s a basic example of how to use DBMS_XMLSTORE.newContext in a PL/SQL block:

DECLARE
  ctxHandle DBMS_XMLSTORE.ctxHandle;
  rowsProcessed INTEGER;
  xmlData CLOB;
BEGIN
  -- Example XML data
  xmlData := '<ROWS>
                <ROW>
                  <COLUMN1>Value1</COLUMN1>
                  <COLUMN2>Value2</COLUMN2>
                </ROW>
              </ROWS>';

  -- Create a new context for the 'my_table'
  ctxHandle := DBMS_XMLSTORE.newContext('my_table');

  -- Set the XML data to be processed
  DBMS_XMLSTORE.setXML(ctxHandle, xmlData);

  -- Perform the insert operation based on the XML data
  rowsProcessed := DBMS_XMLSTORE.insertXML(ctxHandle);

  -- Free the context
  DBMS_XMLSTORE.closeContext(ctxHandle);

  DBMS_OUTPUT.put_line('Rows Processed: ' || TO_CHAR(rowsProcessed));
END;

In this example:

A context is created for the specified table (my_table) using DBMS_XMLSTORE.newContext.
XML data is set for this context with DBMS_XMLSTORE.setXML.
The DBMS_XMLSTORE.insertXML function is called to insert the data from the XML into the table.
Finally, the context is closed with DBMS_XMLSTORE.closeContext, which is a good practice to free up resources.

Considerations

Ensure your XML structure matches the table’s schema where you’re inserting or updating data.
Proper error handling should be implemented, as operations might fail due to various reasons (e.g., schema mismatch, constraint violations).
Remember to close the context after the operations to release resources.
DBMS_XMLSTORE is a powerful tool for handling XML data in Oracle databases, simplifying the process of transforming XML into database actions.