Question

Hi Oracle sql programmers, how do you identify double byte character in the db which I mean to find all the data in column 1 in table1 which contain double byte character such as Chinese character(s)?

UPDATE 1: I don’t even know what Chinese characters would be in the column, I just need to find all the first_name and last_name columns which users entered any non-English characters, then change the value to NA.

Answer 1

The simplest option assuming you truly mean non-English (i.e. any character not in the US7ASCII character set) would be something like

UPDATE table_name
   SET first_name = 'NA'
 WHERE length( first_name ) != lengthb( first_name )

LENGTH returns the length of a string in characters while LENGTHB returns the length of a string in bytes. UTF-8 encodes the US7ASCII characters with a single byte. If there are any non-US7SACII characters, the length in bytes will be greater than the length in characters.