1. A function was applied to a non-permitted argument.
2. A two-digit operation was applied to non-comparable values.
3. A predicate contains non-comparable data types.
Each data type can be compared to itself. Columns of data type CHAR with the different code attributes ASCII and UNICODE can be compared to each other; they are implicitly adapted. The columns of code attribute ASCII can be compared to date, time, and timestamp specifications.
All numbers can be compared to each other.