Oracle Message PLS-01451 - The data types of these must be comparable

ERRORThe data types of these must be comparable
CAUSEThe data types of these must be comparable. Section 4.2 of X3H2, Data types, states that: A character string and a number are not comparable values. Many builtin functions in STANDARD will be flagged with this warning by means of a pragma. This warning will be place on data-type coercion functions, for example, TO_CHAR(), that are inserted in OracleSQL to allow non-conforming data type combinations.
ACTIONNone