Informix Error -26187: Cannot select from multiple external tables.

Cause and resolution

Cannot select from multiple external tables.

Only one external table can be used in a SELECT query. For unions, each UNION contributor can have one external table. External tables are allowed as participants in joins and subqueries along with other database tables.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-26187 fires when a SELECT query directly references more than one external table — per the official guidance.

More than one external table used directly in a single SELECT, per the official guidance — the direct, only cause; only one external table is allowed per query (or per UNION contributor).

Solutions / Resolution

Use only one external table per SELECT/UNION contributor, per the official guidance — external tables are still allowed as participants in joins and subqueries alongside ordinary database tables.

Examples

N/A

No specific triggering statement is documented beyond a SELECT referencing multiple external tables.

Diagnostic Checks

Check the query for more than one external table referenced directly (outside a join/subquery), and restructure to use only one per SELECT/UNION contributor.

Related Errors / Related Topics

No closely related error codes are cross-referenced for -26187 in this set yet.

A SELECT referenced more than one external table directly — use only one per SELECT/UNION contributor.