The following rules apply to the value that INDEX returns:
- If string_expression_2 is not found in string_expression_1, then the result is zero.
- If string_expression_2 is null, then the result is null.
- If the arguments are character types, INDEX returns a logical character position, not a byte position, except when the server character set of the arguments is KANJI1 and the session client character set is KanjiEBCDIC.