EXTFNAPIV4_DESCRIBE_COL_CAN_BE_NULL (Set)

The EXTFNAPIV4_DESCRIBE_COL_CAN_BE_NULL attribute indicates if the column can be null. Used in a describe_column_set scenario.

Data Type

a_sql_byte

Description

True, if the column can be NULL. This property is valid only for table arguments. This property is valid only for argument 0.

Usage

The UDF can set this property for a result table column if that column can be NULL. If the UDF does not explicitly set this property, it is assumed that the column can be NULL. The server can use this information during the Optimization state.

Returns

On success, returns the sizeof(a_sql_byte) if the attribute was set or:
  • EXTFNAPIV4_DESCRIBE_NOT_AVAILABLE – returned if the attribute was unavailable to set, which may happen if the column was uninvolved in the query.
On failure, returns one of the generic describe_column errors, or:

  • EXTFNAPIV4_DESCRIBE_BUFFER_SIZE_MISMATCH – set error returned if the describe buffer is not the size of a_sql_byte.

  • EXTFNAPIV4_DESCRIBE_INVALID_STATE – set error returned if the state is not equal to OPTIMIZATION.

  • EXTFNAPIV4_DESCRIBE_INVALID_ATTRIBUTE_VALUE – set error returned if the UDF attempts to set this attribute to a value other than 0 or 1.

Query Processing States

Valid in:

Parent topic: Attributes for *describe_column_set