Informix Error -470: The value of occurrence must be greater than 0.

Reasons / Common Causes

-470 fires when ALLOCATE DESCRIPTOR ... WITH MAX occurrences specifies an occurrences value that isn't a positive integer — a descriptor needs at least one item slot to be meaningful, so zero or negative isn't valid.

1. A literal zero or negative value supplied for occurrences — a typo or sign error.
2. A computed/parameterized value that evaluates to zero or negative at runtime — e.g. a column-count calculation that produces an unexpected result for an edge case (a query with no select-list items yet, for instance).

Solutions / Resolution

1. Modify the occurrences value to be greater than zero and re-execute the ALLOCATE DESCRIPTOR statement, per the official guidance.
2. If the value is computed dynamically, add validation to ensure it's always positive before constructing the ALLOCATE DESCRIPTOR statement.

Examples

A negative or zero occurrences value

ALLOCATE DESCRIPTOR 'desc1' WITH MAX 0;
-- -470: occurrences must be greater than 0

Fix — use a positive value matching the expected number of columns/parameters:

ALLOCATE DESCRIPTOR 'desc1' WITH MAX 10;

Diagnostic Checks

1. Check the actual occurrences value being supplied, especially if computed dynamically.
2. Trace back to where a zero or negative value could originate, if the value isn't a plain hardcoded literal.

Related Errors / Related Topics

• -469 — "This descriptor does not exist." A related descriptor-usage error, about a missing allocation rather than an invalid parameter on the allocation itself.
• -447 — "The numeric value provided for the FIRST, LIMIT or SKIP clauses must be greater than zero." A conceptually similar "value must be positive" restriction, in a different clause context.

Ensure the occurrences value supplied to ALLOCATE DESCRIPTOR ... WITH MAX is always a positive integer, especially when computed dynamically from the number of expected columns/parameters.