Informix Error -370

Reasons / Common Causes

-370 is a structural guardrail: a table must always have at least one column, so an ALTER TABLE DROP that would remove the table's only remaining column is rejected outright.

1. An ALTER TABLE DROP statement dropping every column in a single statement, or the last remaining one after several prior drops.
2. A sequence of ALTER TABLE DROP statements executed across multiple steps (e.g. in a migration script), where the final drop leaves nothing behind.
3. Table cleanup logic that intended to remove the table entirely, but used repeated column-drops instead of DROP TABLE.

Solutions / Resolution

1. If the goal is to remove the table entirely, use DROP TABLE instead, per the official guidance, rather than dropping columns one by one.
2. If the table genuinely needs to keep existing with different columns, revise the statement to leave at least one column — restructure by adding replacement columns before dropping the old ones, if a full column swap is the actual intent.

Examples

Attempting to drop the last column

ALTER TABLE scratch_data DROP (last_remaining_column);
-- -370: scratch_data would have zero columns left

Fix — drop the table entirely if that's the actual goal:

DROP TABLE scratch_data;

Swapping columns without ever leaving the table empty

ALTER TABLE scratch_data ADD (new_column VARCHAR(20));
-- migrate/copy data from old_column to new_column as needed
ALTER TABLE scratch_data DROP (old_column);
-- succeeds: new_column remains

Diagnostic Checks

1. Count the table's remaining columns before issuing an ALTER TABLE DROP, to confirm at least one will remain afterward.
2. Clarify whether the actual intent is to remove the table entirely, in which case DROP TABLE is the correct statement, not a sequence of column drops.

Related Errors / Related Topics

• -328 — "Column column-name already exists in table." Another ALTER TABLE-related restriction, on the add side rather than the drop side.

If the goal is removing the table entirely, use DROP TABLE — a sequence of column drops can never fully empty a table.