CLOB types can only be converted to or from CHAR or VARCHAR types. For example, implicit conversion is performed on CLOB data that is inserted into a CHAR or VARCHAR column. See Implicit Type Conversions.
Comparisons of strings, fixed- or variable-length, require operands of equal length. The following table shows that the shorter string is converted by being padded on the right.
|'x'='x '||'xΔ '='x '||TRUE|
where Δ is a pad character.
If a character is not in the repertoire of the target character set, an error is reported.