NCHAR to CHAR conversions can occur as part of a comparison of CHAR and NCHAR data, or when specifically requested. This type of conversion is lossy because depending on the CHAR character set, there can be some NCHAR characters that cannot be represented in the CHAR type. When an NCHAR character cannot be converted to CHAR, a substitution character from the CHAR character set is used instead. For single-byte character sets, this is usually hex 1A.

Depending on the setting of the on_charset_conversion_failure option, when a character cannot be converted, one of the following can happen:

Therefore, it is important to consider this option when converting from NCHAR to CHAR.

 See also