Informix Error -9602: Illegal attempt to convert a collection type into another type.

Cause and resolution

Illegal attempt to convert a collection type into another type.

You attempted to store a collection of one type in a collection of a different type, or you attempted to move a collection into a host variable that is not a collection. In ESQL/C, a collection host variable declared to contain elements of a specific type can only hold collections of that same type. If you require that a collection host variable hold collections of different types, declare it without the specific type information.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-9602 fires when a collection is stored into a collection of a different element type, or into a host variable that isn't a collection at all — per the official guidance.

Storing a collection of one type into a collection of a different type, per the official guidance — the first named cause.
Moving a collection into a non-collection host variable, per the official guidance — the second named cause; in ESQL/C, a typed collection host variable can only hold collections of that same type.

Solutions / Resolution

Declare the collection host variable without specific type information, per the official guidance, if it needs to hold collections of different types.

Examples

An ESQL/C collection type mismatch

EXEC SQL BEGIN DECLARE SECTION;
  ifx_list_t *list_of_int;
EXEC SQL END DECLARE SECTION;
-- -9602 if a LIST(VARCHAR) is fetched into list_of_int

Corrected — declaring without specific element type

EXEC SQL BEGIN DECLARE SECTION;
  ifx_collection_t *any_list;
EXEC SQL END DECLARE SECTION;

Diagnostic Checks

Check the host variable's declared collection element type against the actual collection type being stored, and declare it untyped if it must hold multiple types.

Related Errors / Related Topics

-9610 — "Illegal attempt to use collection host variable." A related collection- host-variable error, on cardinality/untyped-assignment/derived-table syntax rather than a type-conversion mismatch.

A collection was stored into an incompatible type or a non-collection host variable — declare the host variable untyped, or match the element type.