Key constraint between temporary tables requires a primary key (not unique constraint)

Error constant SQLE_INVALID_FOREIGN_KEY_INDEX
ODBC 2 State 42000
ODBC 3 State 42000
Severity 16
SQLCODE –865
SQLSTATE 42R03
Sybase error code 1709
Probable cause

The key constraint between temporary tables requires a primary key (not a UNIQUE constraint) if the database uses combined indexes. Change the definition of the primary table using ALTER TABLE or rebuild the database.