Oracle’s PL/SQL DBMS_XMLQUERY package is a powerful tool for generating XML documents from SQL queries. It offers a wide range of functions to manipulate and transform query results into XML format, providing flexibility in how data is presented and shared. Among its various features, the setRowTag function plays a crucial role in customizing the XML output.

Understanding setRowTag

The setRowTag function is part of the DBMS_XMLQUERY package, which allows developers to specify a custom tag name for the rows returned by the SQL query. By default, when you generate XML from a SQL query, each row is enclosed in a generic tag, typically <ROW>. However, in many cases, you might want to have a more descriptive or context-specific tag name for each row to make the XML document more readable or to conform to a specific XML schema.


The syntax for the DBMS_XMLQUERY.setRowTag function is as follows:

DBMS_XMLQUERY.setRowTag(ctx IN ctxHandle, rowTag IN VARCHAR2);

ctx: The context handle returned by the DBMS_XMLQUERY.NEWCONTEXT function. This handle represents the current query session and is used to maintain the state across different DBMS_XMLQUERY function calls.
rowTag: A string specifying the new tag name to be used for each row in the XML output.


To illustrate how DBMS_XMLQUERY.setRowTag is used, consider the following example:

  ctx  DBMS_XMLQUERY.ctxHandle;
  xml  CLOB;
  ctx := DBMS_XMLQUERY.newContext('SELECT employee_id, first_name, last_name FROM employees'); -- Define SQL query
  DBMS_XMLQUERY.setRowTag(ctx, 'Employee'); -- Set custom row tag
  xml := DBMS_XMLQUERY.getXML(ctx); -- Generate XML
  DBMS_XMLQUERY.closeContext(ctx); -- Clean up
  -- Output or process the XML as required

In this example, the setRowTag function is used to change the default row tag from <ROW> to <Employee>. This means that each row returned by the SQL query will be wrapped in an tag in the resulting XML document, making it clearer that the rows represent employees.

Benefits and Considerations

Readability: Custom row tags can significantly improve the readability of the XML document, making it easier for both humans and machines to understand the structure and content.

Flexibility: Allows XML documents to be customized to match specific schemas or requirements, facilitating integration with other systems or standards.

Simplicity: Simplifies the transformation of SQL query results into XML, reducing the need for additional processing or manipulation of the XML document.

When using setRowTag, it’s important to ensure that the custom tag names are valid XML tags and do not contain spaces or special characters not allowed in XML tag names. Additionally, consistent use of tag names across different queries and XML documents can help maintain uniformity and predictability in data exchange formats.

In summary, the setRowTag function of the DBMS_XMLQUERY package is a simple yet powerful feature for customizing the XML output of SQL queries in Oracle’s PL/SQL, enhancing the clarity, readability, and integration capabilities of the generated XML documents.