How does an Oracle SQL statement determine whether a field starts with a letter rather than a Chinese character?

Recently, I want to check the filling rules of a field in the table, and the results are very confusing. I want to use SQL statements to determine how a field starts with a letter rather than a Chinese character:

1. if lengthb (substr ("", 1,1) = 2 then

Chinese characters

Elseif lengthb (substr ("", 1, 1) = 1 then

Letter

End if

2. Use not like '\ %' to return records starting with a letter,

The returned result starts with a Chinese character using the like '\ %.

Principle: The asciistr () function converts non-ASCII code into binary code and adds \ before it. Therefore, if asciistr (acolumn) is a Chinese character, \

Example: select asciistr ('China') from dual;

China

Therefore, it is easy to distinguish Chinese characters from characters.