Informix Error -2945: You may apply the after add, update, query, or remove commands to a table only -- not a column.

Reasons / Common Causes

-2945's official description covers aggregate placement: per the official guidance, aggregates (AVG, MIN, MAX, COUNT, TOTAL) can only be performed on fields associated with tables (not DISPLAYONLY fields), and those tables must be listed in the opening command of the same control block.

1. An aggregate applied to a DISPLAYONLY field, per the official guidance — the first named cause.
2. An aggregate applied to a field whose table isn't listed in the enclosing control block's opening command, per the official guidance — the second named cause.

Solutions / Resolution

1. Revise the form specification, and recompile, per the official guidance — either drop DISPLAYONLY from the field if it genuinely needs aggregation, or add the field's table to the control block's opening command.

Examples

An aggregate on a DISPLAYONLY field

ATTRIBUTES
  running_total = subtotal, DISPLAYONLY;

AFTER QUERY OF orders
  LET total = AVG(running_total);
-- -2945: running_total is DISPLAYONLY

Corrected

ATTRIBUTES
  subtotal = subtotal;

AFTER QUERY OF orders
  LET total = AVG(subtotal);

Diagnostic Checks

1. Check every aggregate expression's field for DISPLAYONLY status and for whether its table appears in the enclosing control block's opening command.

Related Errors / Related Topics

• -2946 — "You may not calculate an aggregate on the display-only field name." A closely related error covering the same restriction, phrased specifically around the DISPLAYONLY-field case.

An aggregate function is applied to a DISPLAYONLY field, or to a field whose table isn't listed in the control block — revise and recompile.