Returns the size of a field.

The Len and datalength functions can be used.

For example:
Select datalength ('zhang san'); -- Returns [4] Because one Chinese Character occupies two bytes.
Select Len ('zhang san'); -- Returns [2] and treats a Chinese character as a character
Select datalength ('AB'); -- Returns [2] because an English word occupies a byte.
Select Len ('AB'); -- Returns [2] and treats a Chinese character as a character.
3. Expansion: Which of the following effects is [lengthb] in Oracle? [length ]?
4. As mentioned above, the main differences between the two functions are:
Datalength: returns the length of bytes.
Length: the length of the returned characters.