Informix Error -26198: Cannot modify an external table that is also used in the subquery.
Cause and resolution
Cannot modify an external table that is also used in the subquery.
The external table cannot be used in the subquery. Check the statement to see if the external table is used in the subquery.
Oninit® Troubleshooting Guidance
Reasons / Common Causes
-26198 fires when a statement modifying (unloading to) an external table also references that same external table in a subquery — per the official guidance.
- The external table being modified is also referenced in a subquery of the same statement, per the official guidance — the direct, only cause; not allowed.
Solutions / Resolution
- Rewrite the statement so the external table being modified isn't also used in a subquery, per the official guidance.
Examples
N/A
No specific triggering statement is documented beyond an external table referenced both as the modification target and in a subquery.
Diagnostic Checks
- Check the statement for the external table appearing both as the modification target and inside a subquery, and restructure it.
Related Errors / Related Topics
- -26214 — "Cannot perform this operation on an external table." A related general restriction on external-table operations, covering subquery/join/BLOB-CLOB usage restrictions broadly rather than this specific self-reference case.
An external table was both the modification target and referenced in a subquery — restructure the statement.