PLS-00649: method string can be overridden only once per object type
Cause: User tried to override the method more than once in the same subtype.
Action: Either make this an extra overload by removing the OVERRIDING keyword where the method signature is different. The argument types should be reconsidered otherwise.
PLS-00648: type of supertype attribute string can not be a subtype or reference to a subtype in this release
Cause: User tried to complete a type, Tsub as a subtype of another type, Tsuper where Tsuper contained an attribute of type Tsub or of type REF to Tsub. This is an implementation restriction.
Action: Change the design of code to not use any type with attribute whose type is of subtype or REF to subtype.
PLS-00645: character set mismatch found at string among operands in a COALESCE expression
Cause: In a COALESCE expression, the operands do not match in character set and it is unclear which implicit conversion is required to correct the mismatch.
Action: Change the operands so that their character sets match.
PLS-00644: character set mismatch found at string among result expressions in a CASE expression
Cause: In a CASE expression, the result expressions do not match in character set, and it is unclear which implicit conversion is required to correct the mismatch.
Action: Change the result expressions so that their character sets match.
PLS-00642: local collection types not allowed in SQL statements
Cause: A locally-defined (i.e. not schema level) collection type was used in a SQL statement. The type must be defined in a schema to be accepted in a SQL statement.
Action: Define the collection type in your schema, not inside a PL or SQL subprogram.
PLS-00633: RETURN statement in a pipelined function cannot contain an expression
Cause: A RETURN statement in a pipelined function contains an expression, which is not allowed. Pipelined functions must send back values to the caller by using the PIPE statement.
Action: Remove the expression from the RETURN statement and use a PIPE statement to return values. Else, convert the function into a non-pipelined function.